Metal roofing is a popular type of roofing, which is a profiled sheet made of steel, aluminum or copper. Thanks to the zinc coating and polymer protection, the metal tile is a durable material resistant to adverse environmental conditions. In order for the roofing to please for many years with its qualities and appearance, it is worth taking seriously all aspects of its installation, first of all, to the arrangement of the lathing - the basis for the roofing.
The lathing is an important element of the rafter system, which is responsible for the reliability and ease of fastening the roof covering. One of the most popular materials for roofing is metal, because it is durable, durable and lightweight. Even beginners can handle it.
There are several rules that will make the process of installing metal tiles easier:
At the joints (for example, in the valley or around the chimneys), it is advisable to use additional boards and make the crate solid
A sparse lathing is used as a base for metal tiles. Solid lathing is only necessary in some of the places mentioned above. It is not worth using it over the entire surface of the roof, because the sheets of metal tiles perfectly keep their shape on their own, and the close adhesion of the metal tiles to the base contributes to the abundant accumulation of condensate even during daily temperature fluctuations. With a solid base, the ventilation system is not provided, which means that moisture will accumulate, which can lead to the destruction of the crate. In addition, such a roofing covering as a metal tile rests on the base not along the entire length of the slope, but only along the line of the steps, so it does not need a continuous crate as a support. In addition, a solid crate is a more expensive option, and the extra costs in this case are completely unjustified.
For metal tiles, a sparse crate is mounted, because it needs to be fastened only along the line of the steps
Waterlogging of wood leads to a loss of strength of the entire structure, therefore, one cannot do without waterproofing and good ventilation of the under-roof space. A special waterproof membrane is placed on the rafters, fixing it with brackets, and then with bars of a counter-lattice. It is they who set the gap necessary for ventilation, due to which the back side of the metal tile will remain dry. The lathing boards are attached to the counter-lattice strictly perpendicularly. The use of roofing material for waterproofing is undesirable, because in hot weather it will melt, sag and emit an unpleasant odor. The waterproofing is laid horizontally, starting from the cornice, with an overlap of 10–25 cm. It is permissible for the membrane to sag between the rafters by 1.5–2 centimeters, as long as it does not touch the insulation.
The most convenient material for lathing for metal tiles is wood.It is better to use conifers (pine, spruce, fir, larch), but it is permissible to make slats from deciduous materials. Among softwood lumber, pine is especially popular, which is distinguished by an acceptable price, availability and excellent performance characteristics.
The thickness of all boards used for lathing must be the same. Wood should be chosen of high quality, without cracks and large knots, since such defects can provoke a decrease in the bearing capacity of the structure. Boards must be well dried before use, their moisture content should not exceed 18%. Poorly dried wood can deform over time, and this will affect the appearance of the roof. It is important to remember that wood is subject to decay and fire hazard. Wood processing with special means is an important and obligatory stage in any construction work.
After processing wood with antiseptics and fire-retardant compounds, it acquires a characteristic reddish tint.
There are several types of such funds:
The latter type allows you to combine the properties of all compounds into one, saving consumers from the danger of different substances entering into a reaction with each other. Among the most common brands of this type, one can single out the universal remedy "Senezh". Penetrating deep into the wood, it protects it from all adverse factors. Wooden surfaces are treated with a brush or spray devices. The manufacturer's recommendations for the application procedure are mandatory..
The dimensions of the boards or bars are selected individually, depending on the roofing device:
The step of the lathing depends on the wavelength of the metal tile, as a rule, it is provided for by the instructions for a particular type of roof. Since the metal tile has a stepped structure, each of the modules must have a support. That is, each sole of the profile must rest on the board (bar) of the sheathing.
Too large a step will cause the steel to buckle, causing it to become wavy, which will affect both appearance and safety. The most popular standard sizes of metal tiles have a wavelength of 30, 35 and 40 cm. Accordingly, the interval between the elements of the sheathing is determined by the wavelength of the profile. Sheathing boards are laid from the eaves to the ridge.
The step of the lathing should be exactly equal to the wavelength of the metal tile
To correctly calculate the required amount of lumber, you need to know several important values:
Currently, for the convenience of users on the Internet, detailed calculators are presented to calculate the amount of required materials. They allow you to take into account all the necessary parameters to quickly find the best option.
Let us consider the method of calculating the lathing on the example of a gable roof with an area of 120 m².For the lathing, a board with a size of 2.5 × 15 × 400 cm will be used, the spacing between the rows is set by the type of metal tile used and is 35 cm.The length of the roof slopes is 6 m, their width is 10 m.
Thus, to equip the lathing on the roof under consideration, for even counting, 100 boards with a length of 4 m or 1.5 m³ of sawn timber will be required.
Each lathing board must be attached to the counter-lattice bar with two nails or self-tapping screws.
The step between the first and second row of the crate under the metal tile is made less than between all the others
In especially critical places, for example, on a ridge or valley, the crate should be made solid
There are several types of metal tiles, each of them has its own characteristics that should be taken into account during installation. Usually, installation instructions are attached to the metal tile - it should be studied very carefully.
For fastening metal tiles to the crate, special roofing screws made of galvanized steel are used. They are more expensive than conventional ones, but much more reliable, as they are resistant to corrosion. In addition, these self-tapping screws are equipped with rubber press washers, thanks to which they protect the mounting hole from moisture. Another pleasant bonus is a wide range of colors for roofing screws - you can choose the right color for a specific metal tile, due to which the fastening elements will be invisible against the general background.
If you choose the color of the roofing screws exactly in the color of the metal tile, they will be practically invisible
To ensure reliable fixation of the roofing, it is worth considering the correct scheme for fastening the metal tile.
There are the following fastening features:
Roofing screws must be screwed in strictly perpendicularly, without overtightening, but also without loosening the attachment point beyond the necessary
The arrangement of fasteners can be different, as a rule, self-tapping screws are screwed through the wave both horizontally and vertically. In the edge zones, fastening is performed in each wave.
Fastening to the lathing is done with roofing screws directly under the wave, since this is the strongest place of the roofing sheet
Correct installation of the lathing under the metal tile is a guarantee of high-quality installation of roofing material. It is important to familiarize yourself with all the intricacies of a competent foundation for a roofing material, this is the only way to avoid serious problems with the roof in the future.
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The dimensions of the lathing for metal tiles mean the distance between the boards, as well as their section. The step depends on the type of roofing profile and there will be no problems with its definition. The point is that the strongest place in the roofing sheet is at the bottom of the wave. It is in this place that the metal sheet is attached to the base. And in order for the screw to hit the board, it is necessary to accurately determine the distance.
Manufacturers produce three types of profiles, differing from each other in wavelength and metal thickness. There can be 300, 350 or 400 mm between the tops of the waves of the metal tile. And already based on this information, you can calculate the crate. The main distance is a multiple of the wavelength, but the step between the first rail, near the cornice, and the next one corresponds to 230, 280 or 330 mm. This is to keep the roof covering hanging from the roof.
The variety of metal tiles also affects the section of the boards. The minimum thickness, 0.4—0.45 mm, and a small snow load can be selected board for the lathing for metal tiles with a section of 25x100 mm. For more complex options with a tile thickness of 0.5 mm, boards with a section of 32x100 mm are taken. Both cases imply that the distance between the rafter legs is in the range of 600-900 mm.
If the step between the rafter beams is more than one meter, then bars with a section of 40x60 or 50x50 mm are used for the lathing.
Before you start considering the installation process of this roofing material, you need to decide how exactly the material should be used.
Viewing photos of roofs, on which metal tiles look attractive, is far from the best method in this case, since in the selection process you need to pay attention to the list of additional elements, as well as the marking provided by the manufacturer. Consider what the buyer needs to know.
First of all, you need to pay attention to the presence in the price list of such additional elements as:
Thanks to a wide range of colors of metal tiles, you can choose the most aesthetic option for a private house.
Important! The presence of all the listed elements among the seller's offers is an indicator of the level of the company that produces metal tiles, which may also indicate the quality of the products themselves.
In addition, it is worth paying attention to the study of the marking, which must be present on every certified material. Usually, in production, all the characteristics of the material itself are indicated, as well as the level of quality of the anti-corrosion coating that is applied over the sheet.
So, here's what information you can glean by reading the information provided on the back of a sheet of metal tile:
When buying metal tiles, it is important to pay attention to the manufacturer's quality certificates.
In the process of visual inspection, you need to pay attention to the integrity of the protective layer, both on the front and on the seamy side of the sheet, as well as the presence of all mandatory markings.
Important! If we are talking about material purchased from a large manufacturer, then the marking will also contain information on the grade of the steel used.
Like most roof coverings, the profiled sheet is attached to the battens. The step of the lathing for the corrugated board is stipulated in the building codes. SNiP specifies the requirements for this parameter, based on the angle of inclination of the roof slope :
When designing a roofing system, you should decide in advance on the material of the topcoat. Manufacturers of corrugated board in the accompanying documentation indicate the requirements for laying a specific material. It is recommended to calculate the sheathing for corrugated board, in accordance with the parameters specified by the manufacturer (they do not go beyond the requirements of SNiP).
In private construction, corrugated board with a profile of 35 mm in height from a steel sheet with a thickness of 0.6-0.7 mm is often chosen. Such material can be mounted on the purlin in steps of up to 1.5 meters, while the roof is designed for a load of up to 600 kg per square meter.
You can safely move along such a roof when cleaning or repairing, but it should be noted that this structure of increased strength is somewhat more expensive than a roof made of corrugated board of lower rigidity.
If it is supposed to use corrugated board with a profile height of 21 mm or less, the step of the lathing for the corrugated board should be minimal, or a continuous lathing is mounted. This roofing material is not designed for high loads, it requires a solid base to avoid deformation of the sheets.
Profiled sheet with a profile height of 44 mm or more is practically not used in private construction, since this material is intended for arranging the roof of industrial structures .
To calculate the amount of lumber required, you need to know the length and width of the ramp, as well as calculate the step. In addition, it should be taken into account that two boards should be mounted at the ridge and the cornice in order to ensure the necessary strength of the roofing flooring.
Reinforcements also require places of abutment to chimneys, skylights, ventilation ducts, etc. Another 10% should be added to the calculation result. since during the installation process the lumber will have to be cut to the required size and some will go to waste.
The cross-section of the bar must be at least 50 × 50 mm. Also, the lathing can be made of edged or unedged boards with a thickness of 50 mm. It is required to use well-dried lumber. It is recommended to use beams and boards made of spruce, pine, beech, alder. The material may not be planed, but you should pay attention to the straightness of its surfaces.
Boards and beams should not be warped; if necessary, the surface of the elements should be corrected.
The lathing for corrugated board is operated in conditions of high humidity, therefore there is a high risk of damage to wooden elements by fungus and microorganisms. To prevent wood rotting, lumber needs to be treated with antiseptics. Fire protection of roof elements is also required. Today, special compositions for fire-retardant protection are produced, which allow both types of treatment to be carried out at one time.
It is allowed to process an already finished crate, but the roof structure will be much more efficiently protected if it is mounted from elements that have been qualitatively impregnated with a fire retardant compound in advance.
Before starting work, you should calculate the weight of the future roof. Asbestos cement sheets are heavy. Therefore, sometimes a two-layer lathing is used for such a roof.
The work is carried out in the following order:
Each element of the roofing structure has its own purpose. Attention to detail in the construction of this structure is the key to reliable protection of the house from atmospheric influences.
Only if this condition is met, the roof will be reliable and durable for decades.
And even with a strong desire to save on lumber, experts recommend not deviating from the order of installation work and not neglecting such an important element as counter-beams. Even the future owners of a cold attic - perhaps in the future there will be a desire to insulate it and make an attic.
In the technology of the device of all types of pitched roofs, the installation of a counter-lattice is prescribed: these are wooden slats or bars that are stuffed onto the rafters, over the laid waterproofing.
Like the lathing, it is an important part of the roofing pie.
The main difference between the two components is their function. The lathing is the base for the roof covering. Planks attached perpendicular to the rafters transfer the load from the roof to the rafters.
Counter-beams provide ventilation, that is, natural air circulation.
The formation of a ventilation gap between the waterproofing and the roofing is the most important task, because condensation forms on the inside of the roofing.The air flow coming from the side of the eaves will exit through the ventilated ridge, roof aerators.
When the supporting frame made of rafters is assembled, steam and waterproofing is laid.
The counter-lattice beam, as a rule, is mounted in the center of the rafter, on top of the hydro-barrier, that is, the step coincides with the step of the rafters.
The fastener goes through the waterproofing and is driven into the rafter leg.
The elements are hammered in with galvanized knurled nails every 300 mm. Such nails will connect wooden parts several times stronger than ordinary ones, and also reduce the number of splits at the moment they enter the wood fibers.
The upper parts of the counter-rails in the area of the ridge are sawn at the desired angle and connected.
On the site near the valleys, the bars are nailed in 10 cm increments to the bars of the valley.
In other words, from the inner corner of the valley, the counter-bars should be located at a distance of 10 cm, and the fixation is carried out to the boards forming the corner.
This fastening feature is necessary in order to ensure a free drain of water, snow, high-quality condensate drainage, and also to prevent the accumulation of construction waste, which is impossible if the counter-rails are placed tightly to the valley flooring.
In conclusion, it is worth noting: counter-lattice is used not only on pitched roofs, but also for wall insulation, facade decoration, providing effective ventilation.
Competent installation of the roof will allow you to build a reliable barrier that protects the building structure from natural phenomena. To extend the service life of the constructed roof, it is necessary to take care of the exact observance of the technology for carrying out installation work. The battens and counter battens are important pieces of the roofing pie. At the same time, the functions that these structures perform are different and cannot be interchangeable.
What is the difference between lathing and counter-lathing? Not all builders know the purpose of counter rails and the method of their installation. Young roofers often confuse counter battens with battens erected when all roofs are installed. To understand the purpose of each of these elements of the roof, it is necessary to consider why and how they are arranged.
Rows of boards nailed to the rafter system and used to secure the roofing material are called lathing. In construction, there are two types of lathing structures:
Installation of a solid lathing is required on roofs with a small slope when laying the following roofing materials:
When installing continuous flooring, two layers are installed, the first of which is mounted using the method of discharged lathing from boards or bars, and the second is laid from moisture-resistant plywood or cement-bonded particle boards. A 45 degree angle should be maintained when laying the second layer. Solid lathing plays an accompanying role, enhancing the sound and thermal insulation of the roof.
A discharged lathing is constructed from bars, the size of which can be 50x50 mm, as well as 60x60 mm. This type of lathing is necessary for laying steel roofs, corrugated sheets of slate, clay or cement-sand tiles.
Counter-lattice, otherwise called counter-beams, is made of thin wooden bars that are stuffed onto rafters on top of a waterproofing material fixed with a construction stapler. Roofing material, films, hydro-barrier membranes are used as waterproofing. As a result of the installation of the counter-lattice, a ventilation gap is formed between the roofing and the waterproofing layer.
During the operation of the roof, condensation may form on the inside of the roofing. If condensation drops are allowed to accumulate under the roofing material, excess moisture can cause rotting of the roof structure. Counter-beams provide a gap through which moisture is diverted into the drainage system, as well as air currents that dry the roof structure.
For laying counter-beams, bars with a section equal to 30x50 mm are taken. If the roof has a complex structural shape and a large length of rafter legs, then thicker bars with dimensions of 50x50 mm are chosen.
When installing a continuous flooring, the construction of a counter-lattice is mandatory, since only it can provide normal ventilation of the lower surface of a metal tile or other roofing material. Typically, a roofing cake looks like this:
What kind of wood to choose the bars for the installation of the counter-lattice? This issue is very important to ensure the quality of installation and construction work. If you plan to lay a roof made of heavy materials, then pine or oak is ideal as a raw material for the manufacture of counter-beams. If the roof is to be covered with lightweight roofing materials, then softwood varieties can be used.
The counter-lattice device is recommended for all types of pitched roofs. The counter-beams are fastened with galvanized roofing nails to the rafters on top of the fixed waterproofing material, the beams go along the rafters. As a result, it is possible to slightly raise the structure of the crate, namely, to the height of the bar used. In turn, the resulting space provides effective ventilation of the roofing cake. The height of the counter-lattice should vary from 2 to 5 cm.
It is necessary to pay close attention to the frequently encountered errors in the installation of the counter-lattice under the valleys, which consist in the dense laying of the beams to the valley flooring.
Compliance with the recommended distance of 5-10 cm will provide a free flow of rain and melt water between the beams and the support of the valley. In the case of a tight fit, the ventilation of the valleys is disturbed, and the timely removal of condensate through the eaves overhang is also difficult. When arranging shallow valleys, it is recommended to use additional gaskets under the counter-lattice, which is usually a sealing tape. This material minimizes the likelihood of leaks.
If the above recommendations for the construction of valleys and ridge are violated, their structure may be deformed. The boards of the finishing lathing are nailed to the counterrails with special nails, the length of which is equal to the summed height of both bars.
Many builders have a question about the violation of the integrity of the waterproofing layer during the fastening of the counter rails to the rafters. Indeed, on each square meter of surface, at least ten fasteners must be used. It turns out that the tightness is broken at ten points. These places become vulnerable to moisture penetration if the installation is carried out during rainy weather. To avoid this process, roofers need to carry out work on the installation of counter battens, lathing and roofing in dry weather without long breaks. With all the materials in full, professional tools and a qualified team, it is not difficult to do all the work without delay.
Small leaks of moisture through the attachment points of the counter-bars with waterproofing are possible only at the time of installation work. As soon as the roofing material is laid, this defect will be eliminated by itself. Moisture trapped inside the roof structure will be removed in a timely manner due to the presence of a ventilated space.
When arranging the roof of a house with natural tiles, the counter-battens used should have different thickness indicators, namely:
This design allows for maximum reliability of the erected tiled roof. If you carry out the work professionally, then the counter grill will serve faithfully for several decades.
When building a warm roof, the issue of arranging proper ventilation under the roofing becomes the most urgent. A layer of insulation from the side of the room is protected by a vapor barrier, and from the side of the roof - by waterproofing. It is impossible to allow the thermal insulation boards to get wet, as this will lose its properties. Therefore, the presence of a ventilated gap formed by the counter grill is vital. Only in this case, the warm roof will remain so for a long time. The inhabitants of the house will receive a cozy attic, which can be used even during the cold season.
Counter-beams for a warm roof are taken with a size of 40x50 mm. You can take and more powerful - 50x50 mm. When fastening to the rafters through the waterproofing, self-tapping screws are used, the length of which is 90 mm. For the device of the counter-lattice it is not at all necessary to use a solid bar, it can be safely mounted from the available component elements.
Many amateur craftsmen may get the impression that the counter grill is used only for roofing. However, this is not quite true.A similar technology is used in the decoration of facades, where the role of ventilation is also great. Ventilated facades extend the service life of the entire building, preventing the destructive effect of moisture penetrating both the walls of the facility and the finishing materials.
As you can see, the choice of material for the counter grill and its installation requires professional knowledge. You can do it yourself, but how can you avoid mistakes? In addition, roofing works are carried out at a height, which requires a thorough approach to ensuring safety and compliance with all rules. Therefore, you should not save on a team of qualified roofers, which has many years of experience in carrying out such work.
It is better to calmly follow the progress of the roof covering, knowing about the main stages of the roofing pie. Contractors treat construction-savvy clients with respect and prefer not to cheat. After all, they will have to eliminate all the imperfections after you identify them. Although serious companies that have come to the roofing market for a long time are unlikely to spoil their reputation with bad work. Therefore, give preference to well-known companies.
Correct installation of the lathing under the metal tile is a guarantee of high-quality installation of roofing material. Let's highlight the main points for choosing the type and pitch of the lathing, as well as calculating the required number of boards and their size in the case of installing a metal roof.
Before installing the battens, make sure that the roofing "pie" is made correctly. In particular, is there a ventilation gap between the waterproofing film and the board on which the metal tile will be installed? After laying the waterproofing membrane along the rafters, a 50x50 mm bar (counter-lattice or counter-rail) is nailed, with the help of which air will circulate under the roofing material. The counter-lattice spacing is equal to the span of the rafter system, usually 700 - 800 mm.
Roofing "pie" for metal tiles
The main purpose of the counter-lattice is to preserve the roofing material and the wooden structure of the roof due to the "weathering" of excess condensate formed under the metal tile. The rule is valid for both a cold roof and a mansard roof.
As a base for metal tiles, a board is used, the dimensions of which are 25 (30) x100 mm. Its thickness is of no fundamental importance (25 or 30 mm), since the weight of the metal roof does not exceed 7 kg / m2. The material will also easily withstand snow loads during the winter period of operation. The main thing is that the thickness of each board should be the same or with a slight deviation of 2-3 mm. This condition will ultimately allow you to get a flat slope plane.
For metal tiles, three types of lathing can be distinguished: sparse (or stepping), solid and combined... The first type is the most common, since it is used on various roof shapes with a slope of more than 20 degrees. The distance between the centers of the boards in this case is equal to the wavelength of the metal tile.
For shallow structures (14-20 °), a continuous crate is used. Recall that minimum permissible roof slope for metal tiles - 14 degrees. Please note, despite the name "solid", it is not recommended to lay boards close to each other: you must leave a technological gap of 2-3 cm.
The combined laying scheme for metal tiles includes the first two types.Stepping is performed on the entire roof area, except for additional roof nodes: the adjoining of the roof to the pipe or wall, the valley. It is recommended to install a continuous sheathing in these places of the roof.
Solid lathing: on the left - the valley node, on the right - the joining of the metal tile to the pipe
A solid crate must also be installed:
Correct lathing in the ridge area
To determine the pitch of a rarefied (not continuous) lathing, it is necessary to know the wavelength of the metal tile. For the Monterrey profile, the distance between adjacent boards will be 350 mm.
The lathing step is calculated from the center (axis) to the center of the board. The step between the starting and the second board is considered to be from the bottom edge of the starting board to the center of the second.
Sheathing step for metal tiles Monterrey
The distance between the starting board of the sheathing and the second board is 300 mm, while the subsequent pitch of the sheathing of the Monterrey metal tile is 350 mm. This is due to the need to release the roof by 50 mm (see image).
The removal of the roof relative to the first sheathing board for most types of metal tiles is 5 cm.
Here are the data of the most popular types of profiled roofs to determine the pitch of the board for metal tiles:
The rafter system is the supporting frame of the pitched roof. It is a collection of various structural elements fastened together in various ways. The rafter system includes a Mauerlat, rafter legs, puffs, purlins, a base for the roof and other smaller units and parts. They are all connected with studs, nails and other fasteners. The strength of the rafter system, the reliability and durability of the roof as a whole depends on how correctly the type of fastener is chosen.
Traditionally, pins, nails and staples have been used to install the rafter system, but with the advent of electric screwdrivers, the popularity of screws and self-tapping screws has increased, and they are increasingly used in construction work.
Despite the fact that outwardly the self-tapping screw and the screw are very similar, they differ in thread and installation method:
- the screw has a thread in the form of a gimlet, which does not reach the head and is used to fasten parts to soft materials, for example, to wood. Heavy-duty hex head screws are called "wood grouses"
- the self-tapping screw has a special thread along the entire length of the rod and forms a counter thread in the parts to be joined.
To secure the part with a screw, you must first drill a hole. When mounting a part with a self-tapping screw, such a hole is not required.
A common construction nail has a round pointed shank and a flat head. When installing critical units, comb or brushed nails are used. Thanks to the cross-cut on the shank, the fastening strength of a brushed nail is 5 times higher than that of a conventional nail. In conditions of high humidity, screw nails are used, which increase the fastening strength by 4 times.
The holding strength of nails and screws is also different. For example, to pull out a 2.6x40 mm non-galvanized nail from a pine board, you need to apply a force of 32 kg, and pulling out a shorter screw 2.6x22 mm in size will require a force of 74 kg. The fastening made with galvanized nails is significantly stronger than using simple black nails.
It would seem that the conclusion is obvious - when installing the rafter system under the roof of Ondulin, self-tapping screws should be used, but there is no need to rush.The fact is that with changes in humidity and temperature, under the influence of snow and wind loads, the rafter system "breathes", i.e. wooden elements swell, change in size and shift relative to each other, while bending, shear and tensile loads act on the fasteners.
Such loads are not terrible for a nail: its rod easily withstands numerous bends, and if the wood squeezes out the nail during swelling, the fastening still remains strong. The protruding head of the nail is clearly visible, and it is not difficult to drive it in to the end during the next inspection of the roof.
It is easy to imagine what happens to the self-tapping screw when the temperature changes, especially when the rafters and beams are wetted and swollen: the thread does not allow the rod to move and breaks it in one or two places. Very often, the rod breaks at the base of the head, and the mount is completely destroyed. The strength of the steel and the quality of the heat treatment of the self-tapping screw do not matter, because freezing water can destroy even stronger nodes.
The use of self-tapping screws, screws and, in particular, "wood grouses" is possible when installing sliding supports of rafters, clamps and other steel parts, but it should be understood that such fastening will be more expensive, and installation more laborious.
When installing the rafter system of pitched roofs of single-family and block houses with a height of 2-3 floors, it is recommended to use nails of the following sizes:
The roof is an important element of the house that protects the home from outside influences. In private construction, the most widespread are gable and hip roofs.
Gable structures are formed by two inclined planes and must have an inclination angle of more than 2.5 degrees.
Their construction is recommended in regions with high rainfall.
Hip in its structure is similar to a gable roof, but instead of two inclined planes, four are assumed here - the structure is inclined on each side.
The main element of such roofs is the rafters, which are a frame that supports all other components. Rafters are made from a metal corner or a wooden bar.
To fasten the rafter elements, a crate is used - boards 20-35 mm thick, stuffed across the rafters. The lathing is also used to fix roofing materials (slate, corrugated board, metal, etc.). For isolation from noise, cold and moisture, a steam and hydro-barrier is used - which also serves as protection for the insulation.
Counter-rails promote air circulation between profiled sheets, battens and waterproof foil. Roof ventilation here is provided by special technological gaps at the ridge and along the slopes, as well as ventilation windows. Roof installation work must obey the main principle: create the necessary tightness.
Counter grill - it is part of the roofing system in the form of wooden bars, which are mounted on top of the water barrier on the rafters... It is intended for ventilation of the roofing material due to the created gaps. It can be installed with any insulation or roofing materials.
When insulating under-roof spaces, it is not recommended to use foam plastics. These materials do not allow steam to pass through and can create a thermos effect that is harmful to metal and wood. The counter lattice is usually made of a wooden block with a section of 25 × 50 mm and more.... The most reliable is considered to be a lathing made of a bar with a size of 40 × 50 mm. During installation, solid or composite bars can be used.
The difference between lathing and counter-lathing is as follows:
In case of slight differences in the height of parts of the rafter system, the counter-rails help to trim the roof slopes. The counter grill also allows roofers to move around the structure without damaging the insulation (roofing felt, etc.).
Counter grill - what is it (photo example):
The roofing cake is a special structure that protects the roof from various negative influences, and consists of the following elements:
The features of the installation of the roofing cake depend on the material for the roof base.
In 99% of cases, a cold attic is uninhabited, with no heating. This design requires powerful ventilation.preventing the accumulation of condensation and moisture. Therefore, the counter-latticecreating a ventilation gap between the roofing material and the waterproofing, should be present.
The counter grill will also allow you not to process the crate with a special protective compound.
The construction of a counter-lattice begins with the selection of raw materials. When the roof is arranged with a cover of heavy weight, for counter-beams it is recommended to choose pine or oak wood.
Flexible shingles and other options for lighter roofing imply the choice of soft wood (aspen, etc.). Standard thickness of counter rails in traditional roof conditions is 30 × 50 mm.
For more complex structures, counter-rails with a cross section of 40 × 50 and 50 × 50 mm are suitable. The height of the counter lattice can be 20-50 mm, the length of the bar is 1.5 m.
At the same time, more and more developers are using high-quality modern materials that are highly reliable and durable. Such materials include waterproofing membrane, film, etc.
Most roofing (including profiled sheet) involves the use of counter-bars with a cross section of 30 × 50 mm. For an example of mounting a counter-lattice, consider its installation under a metal tile. After fixing the waterproofing film on top of the rafter structure, carry out the packing of the counter-lattice.
The dimensions of the counter-lattice for metal tiles are usually 135-137 cm in length and in a section of 30 × 50 mm. They are fixed with galvanized nails with an approximate step of 30 cm.
Installation of counter-lattice for metal tiles is executed in the following sequence:
The counter grill can also be treated with a fire retardant, which reduces the risk of fire in the structure.
Performing these actions will allow you to solve a whole range of tasks for roofing:
The technology of installing metal tiles can include stuffing rough boards or beams for moving on the roof.
Do-it-yourself installation of a counter-lattice for metal tiles:
The main purpose of the installation of counterbeams is the device of a ventilated channel for waterproofing... For protection from water, a film, roofing material or membrane can appear. Ventilation is created here between the waterproofing, standard battens and roofing.
Gradually, condensation can accumulate from the inside of the coating, which can cause rotting of the structure, which is prevented by the counter grill, since excess moisture is removed due to the movement of air. It is better to take the bars with a section of 30 × 50 mm. with a more complex structure - 50 × 50 mm.
If you are engaged in the construction of a modern roof, be it corrugated board, slate or metal, be sure to install counterbeams. Places of overlaps and joints of any roof covering do not imply complete tightness. And the counter-lattice will allow you to fix the waterproofing film and thereby improve the quality characteristics of the entire structure.
The device of a roof made of metal tiles is a crucial stage that completes the main work on the construction of a house. It is important to perform it as accurately as possible and in accordance with the recommendations of specialists. The correct installation of the counter-lattice is of particular importance, since it determines the conditions for the long-term operation of the structure.
The installation of the roofing system is carried out in layers, each of which has its own purpose. In this way, a device called a roofing pie is formed. Its purpose is to perform several specific functions:
The ventilation duct in the roofing cake is designed to remove moisture that forms on the inner surface of the metal tile. For this, a counter-lattice is installed on the side ends of the rafter legs. But first, a membrane is pulled over them, which has the ability to pass moisture in one direction. This is facilitated by microscopic holes along the entire surface of the film, which must be installed without tension so that these holes do not deform. Separate strips along the length are laid with an overlap of 7-10 centimeters, and the joints are glued with tape. Initially, the film can be fixed with a stapler, and at the end of its laying, bars 25x50 or 40x50 millimeters in size, which are called counter-lattice, are packed on the edges of the rafter legs.
Membrane films have long been used in large quantities abroad. However, many domestic developers do not appreciate this material and, trying to save on building materials, use ordinary solid polyethylene. Perhaps there is a lack of information, which indicates a low culture of design and installation.
By and large, any layer between several volumes of confined space is called a membrane. But in our case, we are dealing with selective passage partitions, selectively allowing moisture in the form of vapors to pass through. The practice has developed to call such partitions membranes, and a continuous film of polyethylene vapor barrier or waterproofing.
Membrane film allows moisture to pass in only one direction
If a metal tile is chosen as the finishing coating of the roof, it is advisable to use a bar of 50x50 millimeters for the counter-lattice. This is due to the fact that this sheet is vertically profiled, and therefore, the space under it has a variable section.
Metal roofing tiles are formed from galvanized steel, aluminum or copper sheets. A profile that imitates a natural ceramic coating is made by stamping on special equipment. Various color solutions are obtained by applying reliable protective paint and varnish or plastic coatings.
A sheet of metal tile is galvanized on both sides, and then processed with decorative protective coatings
The basis for the manufacture of inexpensive metal tiles is a galvanized steel sheet with a thickness of 0.4–0.5 mm. Its strength characteristics are determined by the complex shape of the profile, and its durability is determined by the quality of the protective coating. The warranty period of operation is set by manufacturers at 10 years, and the actual service life of the coating reaches 50 years, subject to the recommendations for installation technology.
On top of the counter-lattice, the main support lathing is installed, which can be made from a board 25 millimeters thick. The step of such a lathing depends on the angle of inclination of the roof slope. For angles up to 15 degrees, a continuous crate is made, which allows gaps between the boards up to 50 millimeters. For steeper slopes, the lathing is made sparse in increments recommended by the roofing manufacturer.
Thus, moisture from the roofing cake through the membrane is discharged into the space formed by the counter-lattice and through the cold triangle is removed from the under-roof space. On roofs of complex configuration, it is desirable to use roof fans.
The exclusion of the counter-lattice from the roofing cake is possible only if there are no plans to use the attic in the attic in the future. In all other cases, it is necessary to arrange for effective ventilation of the under-roof space.It should be noted that the counter-lattice is useful in any case, since it can be used to correct mistakes made during the construction of the rafter system and leading to irregularities during the installation of the topcoat.
When installing a counter-lattice, conditions are created for additional thermal insulation and noise absorption from rain and hail is improved. Saving on this roof element can lead to:
From the above, we can conclude that the manufacture of counter-lattice on roofs with metal tiles is mandatory.
Above, it was mentioned about one of the functions of the counter-lattice - leveling the roof. The size of the cross-section of the bars for this element on gable roofs is 25x50 mm, on multi-slope complex structures - 40-50x50 mm.
In practice, the following counter-lattice device technology is used:
If the roof truss system is made of high quality, then the installation of this element does not present any difficulties. Above, the method of mounting the bars of the counter-lattice was described, and you can only add a description of the method for adjusting its level relative to the stretched cords.
To do this, it is not necessary to cut the bar to the desired thickness at every point. You can use liners for them made of thin fiberboard, plywood and other sheet materials of the desired size. In this case, no ledges are formed between the bars, and the main crate will lie perfectly flat.
It should be noted that the bars of the counter-lattice and the board of the main lathing will be in constant contact with moisture, therefore, the antiseptic treatment of these structural elements should be carried out especially carefully.
The fastening of the counter-lattice bars should be as reliable as possible, since large wind loads are transmitted to the rafter system precisely through these parts. In a strong wind of a certain direction, the tearing forces on the finishing roof covering can reach 630 kg per square meter of the roof. Here it is advisable to use self-tapping screws with a length of at least 100 millimeters with an anti-corrosion coating. The step of their installation should be 10-15 centimeters.
There are no trifles or unnecessary operations in modern roof structures. Each step is important and is an integral and justified part of the technology, which must be performed carefully and accurately.
The correct arrangement of the rafter system and the roofing pie ensures the durability of the roof and the comfort of living in the house. Installation errors can lead to significant financial losses for roof alteration. The arrangement of the counter-lattice for the formation of the ventilation space is of great importance. Technologically, the work is quite simple and can be done independently. I wish you success!
The roof is an obligatory structure that is present in any home. It not only protects the living space from winds and precipitation, but also makes the building more attractive and complete. In such a design, a correctly built lathing plays one of the most important roles.
Currently, the choice of roofing materials is very rich, so you can choose the best option for every taste and budget. In order for the coatings to lay correctly and reliably on the base, it is necessary to install a strong and durable lathing. This construction will extend the life of the roof and make it more durable.
The lathing itself is perpendicularly laid beams. These parts are installed on the rafter legs. This structure assumes the main load from the roofing material. In this case, the rafters transfer the weight of the roof to the floors. Correct execution results in a reliable system that will serve for many years.
Another important component of the roofing "pie" is the counter-lattice. This design differs from the lathing in its functions and structure, but not everyone knows what it is.
The counter lattice also consists of wooden bars. They are stuffed directly onto the waterproofing material, onto the rafters. This structure is mounted to form a high-quality waterproofing layer. As a rule, the counter-lattice is installed under the metal tile.
The lathing and counter-lattice under the roof are made of various materials.
Best suited for such work:
Experts do not recommend making such structures from boards whose width is more than 15 cm. This is due to the fact that over time, such a building material begins to warp. Such defects are especially susceptible to areas located across the fibers.
It is quite possible to install such structures with your own hands. Of course, this work cannot be called very simple and fast. The reliability and durability of the roofing material will directly depend on the quality of the lathing you have built. That is why the installation of such systems should be taken as responsibly and seriously as possible. If you doubt your abilities, then it is better not to take risks, but to entrust the work to professionals.
There are two main types of roofing battens. They are solid and discharged. Let's get acquainted with these constructions in detail.
A solid type of lathing is installed using moisture-resistant plywood or OSB sheets (their thickness should be at least 10 mm). Sometimes boards are used to collect this structure. If you are using the latter material, then you should take into account that it fits at small intervals (about 10 mm).
The main advantage of a solid sheathing made of sheet material is, of course, a perfectly flat surface, which is the result. There are no drops on such a structure, unlike options assembled from boards.
However, this system also has several disadvantages.
A solid sheathing made of boards installed with a small clearance is best suited for installation at small corners of the steepness of the roof when laying corrugated board, slate or roofing from a material such as ondulin. As for the metal tile, it is not recommended to use a crate made of boards for it.
The thinned lathing under the roof is recognized as the optimal design. When installing it, the guides must be installed so that the base of each horizontal row of metal tile modules acquires a reliable bottom support and a sufficient width of material for installing self-tapping screws.
In this case, the gap between the axes of the horizontal guides, must necessarily correspond to the longitudinal length of the roofing material modules. Most often, the step between the bars is a few centimeters. This design is well suited for metal roofing, corrugated slate and natural tiles.
For the construction of a sparse roof, it is permissible to use boards with a thickness of 20-40 mm. In this case, the dimensions of the bars can be 50x50 mm or 60x60 mm, and the diameter of the pole is 70 mm.
In this case, the choice of a suitable material for the manufacture of lathing largely depends on the roof and its features. For example, wood used in construction must be at least 2 grade - knots and other defects must not be present on the material. It is advisable to choose an edged board.
If an unedged board is used in the manufacture of a sparse lathing, then its edges must be cut down. It is not recommended to purchase materials whose width exceeds 140 mm - such boards may deform over time.
When creating a sparse structure of the lathing, it is necessary to choose the material:
Very often, a flat solid crate is laid on top of a sparse one. Of course, such a device is optional. It is quite permissible to mount a solid structure without first erecting a rarefied base.
As mentioned above, various materials can be used to construct roof battens. The main condition for choosing is their ideal quality. Only with the use of reliable and durable bars over time, sags or bumps will not appear on the structure. In addition, the flooring itself must be strong enough not to bend under the weight of an adult.
Attention should be paid to the size of the nails that you are going to use when installing the battens. To calculate this indicator, it is necessary to ensure that the length of one nail is not less than twice the thickness of the board to be nailed.
It has already been said above that the type of counter-beam and the main lathing, first of all, depend on the material from which the roof is made. For example, under sufficiently rigid coverings, such as metal profiles, tiles or slate, a sparse construction of boards can be used.
The most popular roofing materials are:
Most types of shingles (with the exception of metal) are small piece elements. Such materials are of the highest quality and are easy to install due to their many positive properties and long service life.
The heaviest materials are recognized as shingles. For this reason, they must be laid on the most durable and strong crate and base. For this, it is recommended to use solid bars with a cross section of 50-60 mm.
One of the most common roofing materials is slate. The main advantage, because of which many consumers choose such coatings, is that they are compact in size, so they can be easily laid on bars, the dimensions of which are no more than 50 mm. In the process of installing larger slate sheets, it is permissible to use lathing elements, the thickness of which is about 80 mm. The step in this case directly depends on the dimensional values.
Large slate sheets should be installed in such a way that there are at least three supports under them. This condition must be observed so that such a roof over time begins to sag under the influence of its weight and precipitation.
Seam roofing is not so popular at the present time, however, sometimes it is still used in the design of the roof. Its slope, as a rule, is within 14 degrees. As for the configuration of such a roof, it is quite complex and intricate, therefore experts strongly recommend installing it on solid types of lathing.
A simpler and more undemanding installation is a flexible roof. However, for its installation, a one- or two-layer solid lathing is required. The weight of these building materials is light, so it is not so difficult and energy-consuming to install them.
Now let's take a closer look at which step of the lathing is suitable for certain types of roofing materials:
Before proceeding directly to the installation of a high-quality and reliable lathing, it is necessary to make all the calculations, since you cannot do without them in construction.
To calculate the required volume of building materials, you need to know the following parameters:
If it seems to you that it is a very difficult task to independently draw up a project for a future structure, then you can use a special online calculator, which will quickly and automatically determine all the necessary parameters.
It is quite possible to do the installation of the lathing under the roofing material with your own hands. First, you should stock up on all the necessary tools and fasteners, which include:
When you have purchased all the tools and materials, you can proceed to the preparatory work. You should not neglect them, otherwise, as a result, the structure may turn out to be unstable and short-lived, and it will be very difficult to install it.
Tiled roofs have been used by man from time immemorial. You can even safely say that such a coating is a kind of standard for an exemplary neat roof of a house. Once used everywhere, with the arrival of sheet roofing materials, shingles have somewhat "gone to the side". This was quite understandable: laying large sheets is incomparably easier than piece parts, and the base for the sheet covering is mounted much easier. Thus, tiles from the category of ordinary roofing gradually "migrated" into the group of elite ones, which are not available to everyone, due to the complexity and high cost of creating such a roof.
Roof lathing for metal tiles
However, manufacturers of roofing materials, responding to consumer requests, found a very profitable solution - a "symbiosis" of sheet and tile coverings was created. That is, the result is a combination of simplicity and speed of installation, affordable prices and the possibility of self-assembly with an appearance that very reliably imitates a natural piece of tile covering. Of course, we are talking about metal tiles.
This roofing material immediately became extremely popular. One of the reasons for this success was, for sure, the ability to carry out the installation of the coating with your own hands. It is not complicated if the roof lathing was correctly installed under the metal tile. So let's see how to independently complete this stage of work according to all the rules.
In order to correctly understand the principle of creating a lathing for a roofing made of metal tiles, one must have an idea of the structure of this material and how it is generally attached to the base.
So, a metal tile is a profiled metal sheet covered with a special protective and decorative coating. The material of manufacture is most often steel - cold-rolled sheets with a thickness of 0.4 to 0.7 mm. Much less often, but still there are metal-tile coatings made of aluminum and even copper. They are, of course, much more expensive than steel ones, so they are not in particularly wide demand.
On the production line, metal sheets are passed through special machines, where with the help of special shaped rollers, due to the plasticity of the metal, they are given the desired relief.
The relief of the pavement is designed in such a way that it faithfully imitates a natural tile covering.These are so-called modules located in horizontal and vertical rows, each of which is ready-made and is a "dummy" of piece tiles.
The sheets of such a covering are given a relief configuration that imitates the whole section of the roof, covered with horizontal and vertical rows of "classic" tiles.
This form of relief, in addition to purely decorative qualities, gives several more "preferences":
The relief of the metal tile greatly facilitates the installation of the coating - the sheets in the interlocking areas are ideally aligned with each other, and it is very difficult to make a mistake
There are many types of metal tiles on sale, produced by domestic and foreign companies. Recently, small regional firms have appeared that have purchased and installed production lines, and now they independently produce corrugated board and metal tiles of quite acceptable quality from finished coated steel sheets, thereby meeting the demand needs in the settlement and the nearby administrative region. But more often than not, this is done anyway according to the "patterns" of proven and proven models of well-known manufacturers.
This publication is not intended to address the aesthetic or performance benefits of roof tiles. We are more concerned with the question of how to ensure that these advantages are revealed in full force, that is, how to create all the necessary conditions for high-quality installation of the coating. But for this you need to get acquainted with the geometric structure of the metal tile - with its basic linear parameters.
The main indicators are shown in the figure below:
Basic geometric indicators of any metal tile
2 - useful sheet width. Naturally, it is less than the general one, since the edge half-wave of the metal tile is designed to overlap with the adjacent sheet. When calculating the amount of material for the roof, it is this value that is used.
3 - the total length of the sheet of metal. It depends on the capabilities of a particular manufacturer and on the wishes of the customer. So, various firms offer consumers sheets with a length of 5 ÷ 6 to 8 meters. In fact, you can order the material in such a way that one sheet covers the entire length of the ramp from the eaves to the ridge. On the other hand, it is not always convenient for the production of installation work at a height - they are due to the difficulty of lifting a long sheet onto the roof without the risk of deformation. And, in general, it is undesirable to use sheets with a length of more than 4 meters. However, this rule is advisory in nature.
4 - the length of the module or, as it is often called, the longitudinal step of the metal tile. But this parameter is extremely important for arranging the lathing, since it is from it that the distance between its guides depends.
The variety in this parameter is not so great. Most often, you have to deal with metal tiles with a module pitch of 350 mm. Roofs with large long modules of 400 mm are also popular.However, there are models with a length of "tiles" of 300 mm, and models of the "Retro" type are also more "discrete" - with a longitudinal wave step of 200 and even 150 mm.
5 - wave height - profiles of different models can differ significantly. It is generally accepted that the higher the wave, the more pronounced the indicators of the spatial rigidity of the material and its resistance to external bending loads. True, this affects the useful width of the sheet of metal tiles - it becomes smaller.
6 - it is clear that since the sheet imitates the laying of a real tile, it has a stepped shape - each successive module in the direction from bottom to top starts from a step. The height of this step can be different - from 10 to 20 mm or more, depending on the model.
Usually in advertising materials and in technical documentation for metal tiles, there is both a sketch of the coating and two schemes - the longitudinal and transverse configuration of the sheet. Understanding such a scheme is not difficult at all. It is clear that the choice is always made primarily according to the external qualities of the roofing material, but knowing its geometric parameters is still no less important.
Such schemes are usually available in all stores, including on online trading platforms that sell metal tiles.
Below is a table that may help you make a preliminary selection of roofing material. Along with the illustration, it also contains the main linear parameters of the most popular metal tile models.
In order for the roofing material, even with its considerable spatial rigidity, to be able to withstand external loads (snow, wind, etc.), it must have reliable support. And due to the fact that the metal tile is given a stepped shape, a point, or rather, a support line, must have each of the modules. That is, each "lower tooth" or, as it is also called, the sole of the profile must abut against the lathing element. How it looks is shown in the diagram:
In fact, each module rests against the crate at two points - above and below.
Fastening to the lathing is done with roofing screws, which are placed directly under the step. The layout of the fasteners may differ from model to model, but basically they are screwed in through one wave, both horizontally and along the slope line. In the marginal zones (along the cornice, pediment, valley and ridge and along the overlap line of the sheets), fastening is usually made to each sheathing guide.
One of the recommended schemes for attaching metal sheets to the crate
These rules, in general, predetermine the design of the lathing for metal tiles.
The lathing for metal tiles can be created solid or sparse.
A solid crate is mounted from sheets of moisture-resistant plywood or OSB, at least 10 mm thick, or from boards, however, laying them not entirely solid, but at intervals of the order of 10 mm. Both options have their drawbacks.
Continuous sheathing of sheet materials is required for flexible bitumen shingles. For metal tiles from it, rather, there will be more harm
- Firstly, this is a very costly business, since OSB and, in particular, plywood will cost significantly more than ordinary sawn timber.
- Secondly, the most tight fit of the metal tile with the base over the entire area is by no means a blessing. The high thermal conductivity of the coating will necessarily lead to the formation of condensation even with daily temperature fluctuations. But the ventilated gap for free evaporation of moisture and the release of water vapor is not provided for with this installation.That is, moisture will begin to accumulate under the roofing with all the ensuing (sometimes it has to be taken even literally) consequences.
- Thirdly, if you look again at the diagram, which shows how the metal tile modules rest against the base, it becomes clear that such a crate, in general, is not required at all.
For shingles - yes, this becomes the best base. But for sheets of metal tiles, it is quite possible to apply cheaper and more practical solutions.
Solid lathing from the board. Recommended for some roofing applications with small slope angles. But for a metal tile, its necessity is doubtful ...
But the metal tile is fundamentally different from the above-mentioned roofing coverings already in that it rests on the surface not along the entire length in the direction of the slope, but only along the line of steps between the modules.
Let's look at a similar diagram again:
Diagram explaining the dubiousness of the advisability of using a solid plank sheathing for metal tiles
As you can see, some of the guides, and they are quite impressive, do not perform any supporting role at all, since the profiled sheet simply does not rest on them (circled for example with a large ellipse). In addition, it is impossible to exclude the possibility that, when installing sheets of metal tiles, the self-tapping screw will fall either between the boards of the sheathing, or into the edge of the board, thereby causing a chip or not ensuring the reliability of fastening at this point.
In other words, there is no technological need for a solid board crate, and in terms of the economy of material consumption, it will be great to lose to a sparse one. This can be clearly seen below when it comes to materials.
This option seems to be the most optimal. As it has probably already become clear, it is necessary to place the lathing guides in such a way that the bottom of each horizontal row of metal tile modules has a reliable support below and a sufficient width of material for screwing in the roofing screw.
For a reliable roof made of metal tiles, a sparse sheathing is quite enough
It is easy to assume that the step between the axes of the horizontal guides should exactly correspond to the longitudinal length of the metal tile modules, that is, exactly the parameter on which the emphasis was made above.
An approximate diagram of a sparse sheathing is shown in the illustration below:
An approximate diagram of the structure of a rarefied lathing for metal tiles
So, consider the structure of the structure:
The rafter legs (pos. 1) will serve as the basis for the installation of the battens. However, it would be a mistake to fix the guides directly on them - it was already mentioned above about the danger of condensation accumulation under the metal coating. And waterlogging of wood, especially of such load-bearing parts, which are rafters, leads to a loss of durability of the roof structure. Therefore, the roofs of the waterproofing membrane (item 2) are first fastened to the rafters with brackets, which are then finally fixed on them with counter-lattice bars (item 3), which are attached along the length of the rafter legs.
A waterproofing membrane is laid along the rafters in horizontal rows from bottom to top, which is then fixed on them with counter-lattice bars
For counter-lattice, bars with a cross section of 50 × 50 mm or strips of 30 × 50 mm are suitable. The counter lattice not only fixes the waterproofing and becomes the basis for fastening the lathing guides.It sets the very necessary ventilation gap between the roofing and the rafter system, thanks to which the back side of the metal tile will be effectively ventilated and remain dry.
As a membrane, you can use any durable film that does not allow water to pass through. But if the roof is made insulated, then it is necessary to use a special diffuse membrane that does not delay the release of water vapor from the thermal insulation layer.
To the beams of the counter-lattice, strictly perpendicular to the rafter legs, the guide lathing is mounted. For them, either a board or a bar is used. There are no strict rules for the choice of material, but there are recommendations proven by practice.
For guides, battens are usually used, depending on the design features of the rafter system, or boards with a thickness of 25 and 32 mm, or a bar of 50 × 50 mm.
Installation starts from the bottom, with the starting guide (pos. 4). In this area, it is necessary to take into account some of the nuances:
- Firstly, the guide is attached along the edge of the rafter legs (or filly, if it is with their help that the eaves overhang of the roof is created).
- Secondly, the thickness of the first guide should be greater than the rest. This is due to the need to compensate for the drop-step, which on this line extends beyond the sheathing to the outside. The amount of thickening of this guide is usually equal to the step height of the selected metal tile model.
- Thirdly, the sheet of metal tile should go out by 50 mm to form the eaves overhang. In addition, it is in this area that a cornice board is also nailed to the rafter legs. That is, the distance between the first and second guides (shown in the diagram by the letter "a") should be reduced. It is usually assumed that this step is less than the one set for all other battens by 70 mm.
Other variations are possible here. For example, a board with a beveled trapezoid edge is used to facilitate the flow of water from the waterproofing membrane.
One of the possible options for arranging the eaves node of the sheathing for metal tiles
In addition, it is recommended not to spare the additional board and attach it close to the starting board. Such a measure will strengthen this knot, which is quite vulnerable to loads, and will facilitate in the future the fastening of wind boards along the gable overhangs.
So, after the start, the second guide is mounted with a specific step, and from it - all subsequent ones (pos. 5) up to the ridge. The step between them is kept uniform (marked with the letter "b" in the diagram), in accordance with the length of the module of a particular roofing model.
There are some peculiarities in the ridge area as well. Regardless of the set pitch, a finishing rail is attached along the ridge line (pos. 6). That is, the distance between it and the previous board or timber is determined already in place, but it is necessarily less than the set step. It is in this guide that the upper edge of the roofing will be attached, simultaneously with the installation of the ridge elements. The thickness of the board is also selected already in place - depending on which section of the module along its length will have the cut line of the metal tile. By the way, often, by analogy with the cornice knot, in the area of the ridge, reinforcement is also done by installing an additional board.
In addition, valleys are a special node, that is, the intersection of the roof slopes with the formation of an internal corner. This is perhaps one of the most vulnerable areas in terms of possible leakage, therefore, special care is required here both with waterproofing and with the installation of additional elements that ensure free drainage of rain and melt water.
As a rule, along the line of the valley, the crate on both sides of it is made solid
Usually, along the line of the valley, the crate is solid. This can be implemented in different ways, for example, along the valley, on both sides of it, two or even three boards are piled up.
There are nuances in the design of the lathing even if a brick chimney passes through the roof. How this site is arranged is well shown in the diagram below.
Framing the opening for the passage of a brick pipe with a crate
A similar approach is practiced (only without leaving a fire gap) if it is necessary to frame future roof windows, brick ventilation ducts, etc.
No special tools are required for the installation of the lathing structure. Usually the necessary set is in every home.
In order not to fool yourself when installing the guides before fixing them, it is best to make several templates (builders often call them "horses").
Various types of "horses" - templates for exact observance of the step of installation of the lathing guides. If you want, you won't be mistaken ...
These devices can be factory-made, with the ability to adjust to the desired size. But in the practice of private construction, self-made ones are usually used, made of bars, to which two transverse support bars are nailed, setting the pitch of the lathing. And even evenly sawn-off pieces of timber, which will create a gap between adjacent guides, act as "horses". True, in this case, it is important not to be mistaken with the length of these bars - it should be equal to the pitch of the sheathing minus the width of the material used (of course, all lumber in this case should be exactly the same).
About what lumber are necessary to create the crate, already mentioned above. Therefore - just a couple of words in addition.
It is clear that not everyone has a device that allows you to control the residual moisture content of wood. Hence, materials must be purchased from trusted suppliers.
Often, lumber is sold already treated with impregnation. If not, then you will have to do it yourself, and proceed to installation only after the boards are completely dry
To simplify the calculations of the required amount of lumber, two calculators can be found below:
As already mentioned, there is no special need for a continuous crate for metal tiles. But sometimes the design features of the roof lead to the idea of its expediency. Therefore, we consider:
Here, the dependence on the model of the sheets of metal tiles is already traced, and it is the size of the sections of strengthening the structure.
By the way, the proposed pair of calculators makes it possible to compare how a sparse crate is more profitable in terms of material consumption.
Now - oh fasteners.
It is not recommended to use nails that are too thick - they can cause cracks in the boards or bars of the counter-lattice when hammering. The best option, by the way, is not ordinary nails, but sharpened or screw-rolled.
On the left are 3.2 × 100 mm sharpened nails, on the right - screw-rolled nails 3.4 × 90. Both those and others have an anti-corrosion zinc coating, provide the highest reliability of mating parts
If self-tapping screws are used, then it seems optimal to use not cheap "black" ones, since they are poorly protected from corrosion, and the roofing structure is still made with the expectation of long-term operation. It is recommended to buy "white" or "yellow", that is, having a reliable anti-corrosion coating.
By the way, now on sale are self-tapping screws for especially critical wooden structures, to which, for all reasons, can be attributed to the entire rafter system with a crate.
Self-tapping screws for wood for particularly critical structures
Such fasteners, in addition to high-quality protection against corrosion, are also equipped with a second run of coarse threads, which ensures an extremely reliable connection of wooden parts.
You will have to figure out the number of nails or screws yourself. It is assumed that the connection of the sheathing guides should be carried out at each intersection with the rafter leg:
Fastening the battens to the rafters
1 - rafter leg, or more precisely, a counter-lattice bar launched over it.
3 - knot of the usual intersection of the rail with the rafter leg. When using boards, fastening is carried out on two nails (self-tapping screws). At the same time, in order to prevent cracking, the distance from the edge of the board to the center of the fastening element should be at least 20 mm. It is clear that if a 50 × 50 mm beam is used, then this rule cannot be observed. This means that the fixation is carried out on one nail, but the more important the quality and reliability of the fastener becomes.
4 - joint of two pieces of board or timber. It should fall exclusively on the rafter leg. Each of the boards is fastened with two nails, the timber - with one.
Naturally, fasteners are also purchased with a considerable margin.Even if there are surpluses left, it is not scary, since there will certainly be a use for it in the economy, especially since construction is in full swing.
The basic rules and schemes for installing the lathing for metal tiles are set out above in such detail that, apparently, any good owner familiar with the basics of carpentry and joinery work will easily carry out this work on his own. It probably doesn't make a lot of sense to describe how the boards and beams are measured, cut and raised to the top, how the distance is measured with the help of "horses", and how the nails are hammered.
Better as a practical guide, we suggest that the reader familiarize himself with two videos. One of them shows an animated instruction for the installation of a sheathing system for metal tiles. In the second, the master shares his practical experience, showing the installation on a specific example.
Counter-lattice is made in order to form an air cushion between the slate / metal tile.
An air cushion helps to retain heat, allows a minimum of moisture into the house, creates additional sound insulation, and also helps to extend the life of your roof.
I would like to remind you right away that the material must be selected individually, since everyone has different tastes and finances at home.
The counter grill is made for metal tiles, because it hides all the irregularities, allows the roof to breathe, does not rot, moisture goes into the low tide, thus preventing the tree from rotting, prevents extraneous noise, prevents the rafters from mold.
The protective film is removed from the skates.
If the roof is not gable, but four pitched, in this case, we start installation from the bottom up, making it not big for a whip on each of the ebb tides of 10-12 cm.
The screws are screwed in staggered at a distance from each other in their row from 15 to 30 cm.
The brackets of the snow retainers are screwed to the roof lathing, through the metal tiles, basically they are screwed to the plane of the load-bearing wall.
It is better to fasten the counter-lattice to the lathing with self-tapping screws and nails. This is called a combined mount. It helps to improve fasteners, the way of alignment and avoidance, minor failures in work.
If possible, depending on the distance along the axes of the rafters, put the hydro-barrier vertically (from the horizontal edge of one side of the roof of the house up to the ridge and from the ridge to the other edge of the roof below).
In this case, there will be no additional layers on the roof ridge.
It is not necessary to fasten the crate without a counter-lattice. Such savings on the board will lead you to the fact that the entire roof has to be rebuilt.
The roof of the house is an important element of the building structure. It protects the house from the harmful effects of precipitation and temperatures.
The modern roof has a complex structure and consists of many elements that are mounted in series. Each layer consists of different materials and fulfills its function.
Due to its multilayer structure, the structure is called roofing pie, which consists of:
The counter-lattice for the roof under the metal tile is mounted on top of the waterproofing film along the rafters. It forms a ventilation gap in the roofing cake. It should not be confused with the crate on which the metal tile is attached, they have different purposes.
Building a house with a cold attic does not require the installation of a counter-lattice. If the owner of the house wants to insulate the roof in the future, then it is better to immediately lay the waterproofing under the metal tile and nail the counter-lattice.
When using the attic as a living space or attic, the installation of a counter-lattice is required. It forms a gap for ventilation of the roof space. This facilitates the evaporation of moisture from the waterproofing layer and the inner surface of the sheets.
The distance between the crate and the waterproofing allows you not to pierce it with self-tapping screws when installing metal tiles.
By increasing the air space between the roofing and the insulation, the sound and heat insulation of the roof is increased.
The material for the counter-lattice is durable wood, mainly from coniferous trees. The moisture content of the material should not exceed 20%.
The bars of the counter-lattice must have an ideal structure, without knots and blue discoloration, which often impair the strength of the counter-lattice. They must be of equal length, width and height. This is necessary so that there are no distortions during the installation of the battens.
The standard length of lumber is 2 meters, dimensions are 30x50 mm or 50x50 mm.
The smaller the slope of the roof, the stronger the timber should be. This is due to the increased snow load on the roof surface. If the roof slope is more than 30 degrees, you can use a smaller beam.
Lumber for counter-lattice undergoes mandatory processing of fire and bio-protection. Fire protection increases the wood's resistance to fire. Biosecurity protects wood from the harmful effects of fungi, mold and insects that destroy the structure of the wood.
Typically, the duration of fire protection is 5 years, and biosecurity up to 20 years.
The installation of a counter grill requires compliance with certain rules:
Correctly and evenly mounted counter-lattice contributes to an even distribution of the weight of the metal tile on the rafters.