It has fairly strict requirements for the arrangement of the base on which the roof is installed. This applies to the entire roofing pie. The lathing for metal tiles is also clearly regulated.
The board should be able to support the weight of even a large person. After all, when constructing a roof, it is planned to walk on boards.
In no case can it be said that installation occurs strictly in one way, but the range of options with which installation occurs is small. You can read further about what options there are and how to correctly implement them on a specific roof.
Lathing under metal tiles should be done, if not by professionals, then using professional instructions.
The supporting system, which is properly constructed, is one of the most important elements that affect the overall durability of a metal roof.
In this regard, it is quite difficult to overestimate the role that rafters and the installation of sheathing for metal tiles will play.
If for other types of materials there may be a sufficiently large gap and distance between the frame elements, the cross-section of lumber for them, then it is worth understanding that for metal tiles these indicators are very limited.
This is due to the strength properties of the sheet itself and the specific profile. It has a fairly strict orientation in the direction of installation, as well as elements that are regularly repeated, some areas of which have greater rigidity, some less.
Elements that will be necessary for it to be made of metal tiles:
- profiles 300, 350, 400 or 450 mm;
- nails;
- self-tapping screws;
- lumber (edged board 25x100, 32x100 mm or timber 40x60, 50x50 mm);
- materials needed for waterproofing.
Determining the pitch of the sheathing for a metal roof, the installation of which is planned
The longitudinal profile, which is a periodic wave that differs slightly from the overlapping and overlapping edges, has less influence on the roof sheathing.
However, the profile along the length of the sheet will precisely determine the pitch of the roof sheathing for metal tiles.
There are a number of rules regarding the places where the sheet is attached to the supporting structure for which it is designed. The hardest part of the profile is the one located at the bottom of the wave, almost between the end of one and the beginning of the next. It is in this place that the fasteners need to be installed.
Therefore, in order for the self-tapping screw to be secured, a board or sheathing beam, which is less common, should be installed in this place.
However, it is worth knowing that different manufacturers produce material with different wavelengths. Accordingly, the sheathing step for a metal tile roof will need to be performed specifically for the covering that was purchased.
Different wavelengths are most often associated with different wave heights. The scheme applies here: the higher the profile, the greater its strength.
However, in this case, the width of the sheet will automatically decrease (this is due to the fact that any galvanized metal tile has a size of 1250 mm) and its cost will increase.
The main typical profile dimensions by wavelength are the following: 400, 350, 300 mm, less often 450 mm can be found.
It is important to note another feature. If we consider the profile in a vertical mounting position, its last wave, which in the sheets will extend beyond the next one, as well as the top one, will differ in length from the rest.
The size of the material does not affect the pitch of the metal sheathing.
However, with the first row of boards, which is located along the edge of the rafter legs or fillies, there is a slightly different situation. The distance that exists between it and the second row of the sheathing is smaller, so that in the future, when placing other boards, it is possible to reach a normal pitch.
This shift is fixed and amounts to 50 mm compared to the usual distance. Therefore, the distance will be as follows: 230 and 280, 330 and 380 mm, respectively, for a sheet that has a wavelength of 300, 350, 400 and 450 m.
The distance between other sheets will be equal to the wavelength. All intervals must be measured between the centers of the boards and leveled.
Some features when installing rows of sheathing
It is necessary to start installing the sheathing under the roofing sheets from the eaves, from which the direct installation of the roofing will begin.
Installation of the outermost row of sheathing towards the overhang has 3 important features:
- Due to the fact that the lower edges of all pitched sheets that are being installed will be aligned along it, and it itself is located along the edge of the rafters or fillets, the line of its fastening must be measured with particular accuracy relative to the outer wall of the building. In this case, it is necessary to use a cord, and then cut off the parts of the rafter legs that protrude along the shortest of them. If the removal of the rafters does not allow the formation of a suitable roof overhang (on average 400-500 mm from the wall), you will need to install fillets and use them to level the line.
- Before installing the sheathing, along the height of the edge of the first sheet with subsequent vertical rows, to compensate for the difference, you will need to make the first row higher by the height of the wave, which will differ for each type of profile. This figure can range from 28 to 75 mm. In order to level this protrusion, it is necessary to either install an additional strip along the entire length of the slope, or make similar pads on each rafter. The second option will require less material, but it requires confidence that all inserts will have the same thickness.
- The edge of the waterproofing is passed into the drain through the outer board. It is necessary to make the board beveled along the upper edge to an angle of 120-140 degrees relative to the rafter leg. This will be needed in order to ensure free flow of water and prevent damage to the film.
Consequences that may arise as a result of improper roof sheathing
When installing sheathing over insulation, you cannot make it continuous or with small gaps.
If done incorrectly, the material may subsequently exhibit the following defects:
- Inconsistency of sheets during installation.
- Poor fastening to the metal roof sheathing.
- Wrinkling of the ramp covering.
- Problems with fastening the cornice and gable strips during installation.
Regarding the sizes of lumber that are used to install roof sheathing under metal tiles, it is worth knowing that there are 3 most common types:
- Edged board 25x100 mm. The most common option, which can be suitable for most roofs with a structure that is not too heavy and complex.
- Edged board 32x100 mm. Such a board can be used to lay metal tiles on the basis of a thick galvanized sheet (0.5 mm), as well as for laying on roofs that have a complex structure.
- Beam 40x60 or 50x50 mm. Most often used on roofs that have a non-standard large pitch between the rafters (usually 60-90 cm, but for various reasons it can sometimes be 1 or more meters).
Installation of sheathing and reinforcement strips includes: 1 - rafters; 2 - counter rail; 3 - waterproofing film; 4 - vertical sheathing; 5 - horizontal lathing; 7 - initial horizontal lathing; 15 - insulation; 16 - vapor barrier film.
There are places where the sheathing should be continuous. Without fail, these will be valleys (as a rule, longitudinal sheathing is installed, which has a width of 10 mm along each slope) and places of abutment to such over-roof structures as pipes or attic windows.
For the latter, not only a continuous sheathing must be installed, the width of which will be about 150-200 mm, but also its own rafter system, to which the board and timber will be attached.
When installing the sheathing over the insulation, you cannot make it continuous or with small gaps, because this can disrupt the air circulation in the space under the roof and lead to the accumulation of moisture.
Fastening the sheathing when using metal tiles
With continuous sheathing, the boards are usually laid on the rafters parallel to the ridge.
If metal tiles are used as a roofing material, the sheathing must be fastened with nails that must be twice as long as the thickness of the board or beam that is being nailed. Here you need to perform a calculation.
Most often, their diameter is 3-3.5 mm, because larger sizes will lead to splitting of the board.
The sheathing is attached with two nails to each rafter.
The calculation suggests that fastening with two nails is a mandatory requirement.
The pitch of the sheathing is determined by the metal tile. It should be remembered that the calculation was made above.
The main disadvantage of this option is that the number of connections on self-tapping screws can sharply increase, and therefore you first need to make a calculation. In this case, nails can be driven in much faster, and considerable effort will not be required.
Regardless of which option is chosen, it is always necessary to remember that the service of the coating will depend on how correctly the sheathing for the roof under the metal tile is made and the calculation is made.
Metal tiles are one of the most common roofing materials. Made mainly from thin steel(although there are types of metal tiles made of copper or aluminum), stamped in such a way that the finished product takes on the appearance of classic ceramic tiles, the use of which has been proven by centuries of experience.
The surface of each sheet is covered with a special protective layer of polymer-metal coating, which reliably protects the material from corrosion - the declared service life is 15-60 years. looks very solid and elegant. The weight of the material is approximately two times lower than that of slate, which makes it possible to use lightweight material and reduce the load on the load-bearing elements of the building.
If the installation is carried out correctly, there are no problems, although there are some disadvantages: relatively high cost, the possibility of corrosion, the danger of condensation and good sound conductivity - the roof is quite noisy when it rains. When installing, these points must be taken into account and, if possible, try to mitigate the negative impact. In this article you will learn how to make a sheathing for metal tiles and how to correctly calculate the sheathing pitch.
Fastening the coating using self-tapping screws
How to properly make sheathing for metal tiles? We'll talk about this further.
Do-it-yourself installation of lathing under metal tiles
The roof sheathing for metal tiles is carried out from the lower edge of the roof in a certain sequence. We present to your attention - installation of lathing for metal tiles (step-by-step instructions).
- , fastening it to the rafters using slats of the same thickness. They are usually cut from the same board that goes into the sheathing.
- The outermost row of sheathing, which carries gutters and eaves strips, is attached to the slats.
- The next row of sheathing is installed, the wave pitch is measured from the edge of the first row to the middle of the second.
- Subsequent rows are set with calculating the wave step from the center line of the board.
- The installation of rows of sheathing alternates with the installation of a waterproofing film. It is necessary to ensure the tightness of the insulation and seal the joints of the fabric with tape.
- The junctions of the walls are reinforced with an additional row of planks. They are attached to them (ridge, corners, etc.).
- Constantly monitor the condition of the rows, avoid sagging, waves and other distortions. If necessary, place slats and wedges under the boards to level the row.
Metal roofing pie
Important! It is necessary to constantly carry out all available operations to control the maintenance of the plane of the substrate; this will help eliminate deflections and increase the service life of the roof.
Waterproofing and vapor barrier of metal tiles
Metal roofing is most dangerous due to the possibility of condensation. In this regard, no measures will be superfluous, since getting the rafter system and the roof itself wet will damage the roof in a short time. You will have to completely change all the elements, which means a lot of expense and labor. Therefore, it is important to correctly carry out hydro- and vapor barrier of the roof.
The main condition will be the provision between the waterproofing film and the roof itself. This will allow moisture to evaporate, steam to escape through the membrane, and will contribute to preservation.
Air movement is ensured by the sheathing for metal tiles, which creates a sufficient gap between the layers and ensures that there are no points of contact.
CAREFULLY!
Waterproofing metal tiles is advisable even when the attic is non-residential, since water vapor is constantly squeezed out from the interior of the house, which will gradually affect the roofing material. The presence of a cut-off will allow it to be removed without contact with metal, eliminating corrosion.
Useful video
We invite you to watch a thematic video on installing the sheathing yourself:
Conclusion
In conclusion, it should be noted the importance of competent and careful installation of sheathing under metal tiles as an element responsible for the safety and efficient operation of the roof as a whole. The quality of the sheathing determines the service life of the roof, and to some extent, the load on the walls and the general condition of the building. A responsible attitude to the installation of sheathing will allow you to avoid unnecessary costs of labor and money and guarantee the most efficient operation of the roof.
Correct installation of sheathing under metal tiles is the key to high-quality installation of roofing material. Let us highlight the main points on choosing the type and pitch of the sheathing, as well as calculating the required number of boards and their size in the case of installing a metal roof.
Counter-lattice is an important element of the roofing “pie”
Before installing the sheathing, 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 tiles will be installed. After laying the waterproofing membrane along the rafters, a block measuring 50x50 mm (counter-lattice or counter-batten) is nailed along the rafters, with the help of which air will circulate under the roofing material. The pitch of the counter-lattice is equal to the span width of the rafter system, usually 700 - 800 mm.
Roofing "pie" for metal tiles
- Rafters
- Waterproofing (diffusion membrane)
- Counter-lattice (bar 50x50 mm)
- Lathing for metal tiles
- Metal tiles
- Vapor barrier
- Sheathing starting board
- Cornice strip
- PVC ventilation tape or aluminum mesh
- Kapelnik
- Gutter holder
- Frontal board
The main purpose of the counter-lattice is to preserve the roofing material and the wooden roof structure by “weathering” excess condensation formed under the metal tiles. The rule is valid for both a cold roof and an attic one.
Types of lathing
A board with dimensions of 25 (30) x 100 mm is used as a base for metal tiles. Its thickness is not of fundamental importance (25 or 30 mm), since the weight of a metal roof does not exceed 7 kg/m2. The material will also easily withstand snow loads during winter 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 obtain a flat slope plane.
For metal tiles, three types of lathing can be distinguished: sparse(or stepper) solid And combined. The first type is the most common, as 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.
Sparse lathing For flat structures (14-20°), continuous sheathing is used. Let us remind you that minimum permissible roof slope for metal tiles- 14 degrees. Please note that despite the name “solid”, it is not recommended to lay the boards closely: it is necessary to leave a technical gap of 2-3 cm.
Continuous sheathing The combined installation scheme for metal tiles includes the first two types. Stepping is performed over the entire roof area, except for additional roof components: the junction of the roof with a pipe or wall, valleys. It is recommended to install continuous sheathing in these areas of the roof.
Continuous sheathing: on the left - the valley assembly, on the right - the junction of the metal tile to the pipe A continuous sheathing also needs to be installed:
Lathing pitch for Monterrey and other types of metal tiles
To determine the pitch of a sparse (not continuous) sheathing, 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 sheathing pitch is calculated from the center (axis) to the center of the board. The step between the starting and second board is usually considered to be from the bottom edge of the starting board to the center of the second.
Sheathing pitch for metal tiles Monterrey The distance between the starting sheathing board and the second board is 300 mm, while the subsequent sheathing pitch for Monterrey metal tiles is 350 mm. This is due to the need to extend the roof by 50 mm (see image).
The offset of the roof relative to the first sheathing board for most types of metal tiles is 5 cm.
Here are the data for the most popular types of profiled roofing to determine the pitch of the board for metal tiles:
| Metal tile profiles | Lathing pitch, mm | |
| from the bottom of the 1st to the center of the 2nd board | from center to center of subsequent boards | |
| Monterrey | 300 | 350 |
| SuperMonterrey | 300 | 350 |
| Maxi | 350 | 400 |
| Cascade | 300 | 350 |
| MaxiCascade | 350 | 400 |
| Classic | 300 | 350 |
| Kvinta (Kvinta plus) | 300 | 350 |
| Country (Quinta) | 300 | 350 |
| Quadro profi | 300 | 350 |
| Kamea (Cameo) | 300 | 350 |
| Finnera | 300 | 350 |
| Adamante | 300 | 350 |
| Decorrey | 300 | 350 |
| Spanish Dune | 300 | 350 |
| Andalusia | 350 | 400 |
| Joker | 350 | 400 |
As you can see, most profiles come down to two types of sizes between adjacent boards: 350 and 400 mm, which are also relevant for modular metal tiles with hidden fastening (for example, Andalusia or Spanish Dune).
You cannot increase the gap between the sheathing (for example, make a distance through a wave), because deformation of the roofing profile due to snow mass or other mechanical influences is possible.
Lathing scheme for metal tiles from manufacturers
When installing a roof, it is very important to have reliable and authoritative information on the technical aspects of installing each structural element. Manufacturers of metal tiles, as a rule, offer their instructions describing the correct design of their products. Let us give examples with lathing schemes for the most famous brands of metal roofing presented on the domestic market.
Starting sheathing and installation of end strip from Grand Line Please note that to securely fasten the end strip, you should install the support board above the level of the ordinary sheathing. Its height should be approximately equal to the height of the tile profile.
Offers similar schemes Metal Profile, especially focusing in its instructions on the installation of sheathing in areas of the valley, roof fencing and snow retention elements. In all of the above cases, continuous sheathing is required.
Continuous sheathing in the valley area Manufacturing and trading company Unikma in its instructions for installing a metal profile, it pays special attention to fastening roofing screws if the lathing pattern is incorrect (see image below).
Fasteners for continuous sheathing and lathing with imprecise pitch Thus, we can conclude that a continuous deck under a metal roof is undesirable. You should also carefully observe the distance between the boards.
Products for treating wooden roof structures
An important step before installing the rafter system and sheathing is the treatment of wooden raw materials with special means that give additional durability to individual components and the roof as a whole. An important point before choosing an antiseptic is not only the type of wood, but also the general climatic conditions of the location of the construction site. Experienced builders know that in hot climates wood must be protected from fire, and in humid climates - from water.
The main types of such funds include:
- fire retardants (fire retardants);
- bioprotective;
- water-repellent;
- protect against mold and mildew;
- universal means.
One of the most popular and universal antiseptics is "Senezh", which, thanks to its chemical properties, penetrates deeply into the layers of wood, protecting rafters and sheathing from premature rotting, insect damage and other factors that destroy wood.
Wooden roof elements can be treated by impregnating the surface with a regular brush. A more effective and common way of treating wood is to apply an antiseptic using spray devices of a mechanical or automatic operating principle.
Before starting the processing process, the wood must first be cleared of debris and dried.
To fasten the sheathing board to the counter-batten, galvanized nails are most often used, less often - wood screws. It is better to use screw or razor type nails. The optimal nail length is 70 mm.
Each board at the intersection with the counter-lattice is connected to it with two nails in the upper and lower parts at a distance of about 20 mm from the edge of the board.
Fastening sheathing boards under metal tiles If the standard length of the board (usually 6 meters) is not enough, it is better to place the joint of the boards for building up the sheathing in the center of the counter-batten bar (see figure). Knowing the dimensions of the boards, the distance between them, the width and height of the roof slope, you can easily calculate the amount of material for sheathing under a metal tile roof.
The sheathing for metal tiles serves as a kind of skeleton for the roofing. To create it, various materials can be used: boards, beams, metal corners, wood sheets. Such materials are laid in a perpendicular direction relative to the rafter legs, and fastened using self-tapping screws or nails.
Installation of sheathing under metal tiles is necessary to ensure that the mass of the roofing covering is distributed evenly throughout the rafter system. This is important for the normal functioning of the roof and the strength of the entire building structure.
Some features and rules for creating lathing for metal tiles
When installing the sheathing, the following rules should be observed.
- The roof slope angle should not be less than 14 degrees.
- In the area adjacent to the main roof of valleys, roof windows, ventilation and chimney pipes, continuous sheathing is used.
- Brackets for fastening the drain are installed before the gutters are attached. The eaves strip must take its place before installing the roofing material.
- When constructing an attic (living space in the attic), a vapor and waterproofing film should be laid. It will protect the insulation from condensation and atmospheric moisture. Do not over-tighten the film. It is laid from below, with the upper panels overlapping the lower ones. Fasten the film with a construction stapler.
- It is necessary to take measures to ensure ventilation of the under-roof space. This is necessary to reduce humidity in the house, reduce heat loss, and eliminate condensation.
- Each horizontal board for sheathing under metal tiles must be treated with an anti-rot compound.
Continuous sheathing for metal tiles (photo below) is necessary for roofs of complex construction in the area of internal corners.
Calculation of lathing for metal tiles
You can minimize the cost of purchasing lumber if you correctly calculate the design and dimensions of the sheathing for metal tiles. To do this, first measure the dimensions of the slopes (height, length) and add frontal boards and outlets.
The method for calculating the sheathing is simple. If the total roof area is known - 100 m², and boards of 25 × 150 × 4000 mm (thickness, width, length) are used for lathing, then:
- the area of the board will be 0.15 × 4 = 0.6 m²;
- number of boards required for installation 100 ÷ 0.6 = 167 pcs.;
- volume (in cubic meters) of one board 0.15 × 0.025 × 4 = 0.015 m³;
- the volume of all boards is 100 × 0.015 = 1.5 m³.
That is, to install a continuous type of sheathing you will need 1.5 m³ of boards. For sparse lathing, you need to adjust the calculations. A new component is introduced - a step between the boards (beams). 
An example calculation looks like this:
For example, the roof area is the same 100 m², the length of the slopes is 6 m, the width is 9 m, the sheathing pitch is 300 mm. Then:
- for one slope you will need 6 ÷ 0.3 = 20 boards;
- on the bottom slope there is a molding of boards 20 × 9 = 180 m;
- accordingly, the molding on two slopes is 180 × 2 = 360 m;
- number of boards 4 m long = 360 ÷ 4 = 90 pcs.;
- the volume of lumber is 90 × 0.025 = 2.25 m³.
Why is it necessary to install a counter-lattice?
The counter-grid is necessary to ensure the evaporation of condensate accumulating on the inside of the metal tile. Otherwise, the sheathing and other roof structures may suffer from excess moisture: mold will begin to spread and the wood will rot.
How to stuff sheathing under metal tiles to avoid this? It is enough, after fixing the waterproofing film to the rafter legs (this is done using a stapler), to fill beams with a cross-section of 50x50 mm on top of each of them. The sheathing is already installed on top of these beams. This creates the necessary ventilation space. In addition, using a counter-lattice you can level the surface of the slopes.
How to make a sheathing for metal tiles
It is necessary to comply with the parameters of the structural elements for installing the sheathing. The following rules apply:
- rafters are made of timber, the dimensions of which are selected from the range: 50×200, 50×150, 50×100, 100×200 and 100×150 mm;
- the thickness of the boards for sheathing must be at least 25 mm;
- the width of the boards varies between 100 – 150 mm;
- It is better to choose a pitch between the rafters of 600 mm (in any case, no more than 900 mm): this size will make it easier to lay the insulation;
- the first board should be 10-15 mm thicker than the others;
- the sheathing pitch depends on the parameters of the metal tile: 350 - 450 mm;
- the sheathing boards are joined in a checkerboard pattern;
- boards for additional fastening of the ridge should be 25 mm thick;
- the wind board is attached above the sheathing;
- the strength of the sheathing must be such that it can withstand the weight of a person;
- the presence of a drain and the diameter of the gutter should be taken into account: the projection of the metal tile, and therefore the sheathing, depends on the size of these elements;
- boards and beams must be calibrated: such material facilitates installation work and helps improve quality.
It will be easier to fasten the sheathing boards if you set aside the distance between the horizontal elements of boards or beams using a specially made template. Nails should be twice as long as the thickness of the boards and with a diameter of no more than 3.5 mm. Each board is attached to the rafters on both sides with two nails.
Lumber for sheathing is divided into three categories.
- Edged board with a section of 25×100 mm - most types of sheathing are constructed using this material, provided the structure is light and not complex.
- Edged board with a section of 32×100 - used when metal tiles made of thick sheet metal (0.5 mm) coated with a layer of zinc are used as a roofing material. This board is also suitable for constructing complex structures.
- Beam 50x50 mm - laid as sheathing if the distance between the rafters exceeds 900 mm.
About the consequences of installation errors
- The sheathing above the insulation should not have small gaps: this will lead to disruption of air circulation.
- Displacement of the sheathing boards will complicate the joining of sheets of roofing material or weaken their fastening.
- The use of material made from raw wood, which is prone to warping, will cause wrinkles in the sheet covering of the slope.
- The use of nails thicker than 3.5 mm often leads to splitting of the boards. The optimal thickness is 3.0-3.5 mm.
The efficiency of the roof and its service life depend on the correct choice of material, calculation and installation of sheathing for metal tiles.
Here is a tutorial on how to attach the sheathing under metal tiles: video
Thanks to the roof sheathing, the reliability and quality of laying roofing sheets is ensured. To equip the frame, you will need to know some nuances, including the dimensions of the sheathing for metal tiles.
Device Features
Continuous flooring is constructed from timber or edged boards laid end to end. The distance between individual frame elements should not exceed 1 cm. Suitable parameters for timber are 50x50 mm, for boards - 32x100 mm. Before installation, wooden elements are impregnated with antiseptics. It is much more difficult to install the lattice sheathing, although this reduces the amount of consumables. The result is a reduction in financial costs and overall weight of the structure.
The lattice frame is installed after the rafters have been waterproofed. It is important not to forget about the ventilation gap between the film and the wooden structure. It is advisable to make the distance between the individual battens of the sheathing under the sheathing 350 mm: this is the distance from the cut of the bottom board to the middle of the adjacent one. In this way, metal tile sheets are fixed to the lower part of the wave. With this type of fastening, the overall appearance of the roof is much more beautiful.
The initial sheathing board is 15 mm wider than the rest. Typically, the accompanying documentation of the roofing material contains instructions on the pitch of the sheathing. The same applies to the optimal gap between frame elements: for example, taking into account the recommended frame pitch for this material is at least 300 mm.
Sheathing dimensions, cross-section
The main parameters of the frame for metal tiles are the pitch of the sheathing and the size of the lumber. When determining the optimal pitch, the pitch size of the metal tiles is taken into account. This is a very specific indicator, depending on the type of profile being laid. The profile section at the bottom of the wave, during the transition to the next one, is the most rigid. This explains why this particular location is the most optimal for installing fasteners. Unedged or semi-edged boards are usually not used when constructing a frame.
To determine at what distance to lay the sheathing for metal tiles, the following considerations must be taken into account:
- The length of the sheathing step is directly affected by the type of metal tile used.
- Instructions for installing lathing under metal tiles are available in the accompanying documentation for the roofing material. The step is counted from the bottom of the initial bar to the top cut of the second.
- The distance between the first two sheathing elements is taken to be somewhat smaller.
- The cross-section of the sheathing for metal tiles also determines the angle of inclination of the roof and how much the roofing material protrudes beyond the first frame element.
- To measure the projection of the roof, the frontal board is taken as the reference point. If it is not in the structure, then cut the rafters.
- 6. To achieve the correct measurement between the first and second boards of the frame, a building level 120-150 cm long is laid on top of the rafters. This allows you to determine the distance between the top of the first wave and the bottom of the sheet, applying the appropriate markings of the sheathing under the metal tiles.
- Having pulled out the level like a roofing sheet, a square is placed close to the front board: this allows you to set the parameter of the required protrusion on it. The level extends to the marked mark.
- The thickness of the initial board is taken slightly larger than others, which avoids sagging of the roofing material.
- The dimensions of the remaining sheathing lintels are determined from the top of the second element. The distance is taken standard, corresponding to the profile size. Every third rafter is marked in this way: this is explained by the presence of curvature at the board, which requires the need to stretch it along the applied markings.
- Single-row sheathing lintels are fixed to the rafters. Overlapping is usually not used here. The butt run is performed along the rafters.
- All lumber used undergoes mandatory antiseptic treatment.
Rules for the installation and laying of lathing under metal tiles
It is better to avoid joining the entire sheathing on one rafter, because the structure will not be rigid enough. A situation often occurs when the profile has a different wavelength. For this reason, the supporting structure may have different distances between frame jumpers for one type of metal tile. Lightweight, simple structures for products with a low wave height and a metal sheet thickness of 0.4-0.45 mm are constructed from 25x100 mm edged boards. More complex roofing systems are usually equipped with 32x100 mm boards.
The same board is used when laying metal tiles with a significant wave height, with a sheet thickness of 0.5 mm. In both cases, the distance between the rafters is 0.6-0.9 m. Bars with a cross section of 40x60 mm and 50x50 mm are used in cases where the distance between the rafters exceeds 1 m.
Metal tiles are available in three main wavelength sizes - 300, 350 and 400 mm, which directly affects the pitch of the sheathing. This interval is set aside from the center of the jumpers. Having all the necessary data in hand, you can begin calculating the frame for metal tiles.
Adjacent areas
When laying sheathing under metal tiles in the area of the valley, chimney pipe and around roof windows, a continuous structure is used. When arranging the frame, it is important to avoid miscalculations, as this directly affects the strength and durability of the building’s roof. Sometimes, due to mistakes made, it is necessary to redo the roof, which entails significant financial losses. It must be taken into account that dismantled metal tiles cannot be used again.
Construction of a frame for metal tiles - step-by-step instructions
Step-by-step instructions for installing lathing for metal tiles:
- The size of the timber for the rafters is from 50x150 mm. The board for the sheathing must have a cross-section of at least 25x100 mm. Board for counter-lattice – 25x50 mm.
- When fixing the starting board, a cut of the eaves overhang is taken beyond the laying line: protrusions beyond its limits are unacceptable. The first board is chosen slightly thicker than the others in order to compensate for the difference in the level of the support points between the first and subsequent tile sheets.
- The installation of the metal tile sheathing pitch between the first and second lintels is made 50 mm less than the standard frame size. The distance between the remaining elements of the frame is oriented towards the profile size of the material being laid.
- To check the correct distance between the first two jumpers, two edged boards are laid out in parallel on the ground. By covering them with metal tiles, you can check whether its protrusion is optimal for water drainage: if it is larger than necessary, water will begin to overflow through the gutter. If the distance is insufficient, water can be blown by gusts of wind into the space between the gutter and the front board. Sheets sometimes become deformed under the influence of snow loads.
- To apply the markings you will need a construction tape measure. The starting point is the first board protruding beyond the eaves. Next, the end and ridge strips are attached.
- The wind board is installed above the sheathing, at the height of the roofing sheet. This parameter depends on the type of metal tile.
- For reliability, the skate is equipped with an additional board 25x100 mm.
- To ensure proper drainage of water from the roof surface, mounting brackets should be installed before laying the roof. To install the eaves strip, the metal tiles must be laid along the roof overhang.
- When determining where to install the brackets, the installation step of 50-60 cm is taken as a basis. The brackets are attached to the bottom frame board.
- The outer brackets are mounted taking into account the gutter slope of 5mm/1m length. The linear installation of the remaining brackets is ensured by a tensioned cord.
- The gutter must be inserted into the brackets and then installed. The eaves strip is mounted on the sheathing in such a way as to ensure that the edge of the gutter overlaps the lower edge of the strip. This will allow condensation to drain from the strip into the drain. The overlap parameter of the cornice strips in relation to the length is at least 100 mm.
How to install additional items
Additional roofing elements usually include a heating system and gutters. Snow guards consist of special brackets, the installation of which is carried out in a checkerboard pattern. They make it possible to prevent massive snow removal from the roof surface. Most often, buildings next to which there are sidewalks and pedestrian crossings are equipped in this way. It is also advisable to install snow retention elements above the porch or windows. Most often we are talking about tubular and lattice systems, which are often included in the set of metal tiles.
A well-equipped sheathing that meets all requirements and building codes will ensure ease and speed of installation of roofing material. If you do the work yourself, this will allow you to reduce the cost of constructing a roof by an order of magnitude: its reliability is a prerequisite for ensuring comfort indoors. To do this, you will need to know the step-by-step instructions for lathing under metal tiles.