The counter-lattice for metal tiles and other types of roofing is usually represented by bars with a cross section of at least 30 * 50 mm, which are installed over the waterproofing film along the rafter legs in order to obtain a ventilation gap between the under-roofing waterproofing and, in fact, the roof, which ensures the removal of moisture penetrating from the outside under the roofing material.
The installation of the counter-lattice is inextricably linked with the further installation of the lathing under the roofing material on it, therefore, in this article we will comprehensively approach the consideration of these systems.
Advice! For roofs of complex construction with a large number of slopes or with long rafter legs, the thickness of the counter-battens bars can be increased up to 50 mm.
Instructions for installing a counter-lattice under a metal tile
- Finishing roofing from a waterproofing film and fixing it with a stapler over the rafter legs, proceed to stuffing the counter-lattice.
- They arrange a counter-lattice of bars 135-137 cm long and 30 * 50 mm in cross section. Fastening is carried out with galvanized nails in increments of approximately 30 cm, not higher than the lines marked on the film.
- For subsequent work on metal roofing technology, as well as moving along the roof, rough boards or bars are stuffed onto the counter-lattice.
Advice! It is recommended to cut the bars on the ridge at the required angle on opposite slopes so as to achieve the intersection of the planes of the upper edges of the crate at a single point. This will allow you to accurately and accurately calculate the pitch of the crate and mount the bar of the top row of the coating. Ignoring this recommendation can provoke a violation of the design of the ridge in general.
- The main lathing in the valley area is nailed along the rafter legs with a gap of 10 cm to the longitudinal bars of the counter lathing on the valley or ridge or flooring in order to ensure free removal of moisture, snow, dust and construction waste, as well as to ventilate the space under the roof in these areas.
The device of the crate and the calculation of its step
For the majority of tile models, sawn coniferous wood without knots and wane, which is made in accordance with the requirements of SNIP, with a moisture content of not more than 25%, is used for the lathing.
The device of the crate under the metal tile is performed in the following sequence:
- On the cornice overhang, the step of the crate is measured along the outer edges of the first two bars. It is usually 32-39cm. Such a size does not serve as a calculation for the step of the entire crate as a whole and will depend only on the position of the lower row of tiles relative to the gutter.
- The overhang of the lower row of tiles on the gutter is arranged in the amount of 1/3 of the diameter of the gutter and is achieved by adjusting the timber.
- At the end of the fixation of the first two beams of the crate, the upper beam is installed at a distance of 3 cm from the point of intersection of the counter-lattices of the two roof slopes on the ridge. For greater reliability of the ridge, with an increase in the angle of inclination of the roof by more than 30 degrees, the specified distance can be reduced to 2 cm.
- The distance is measured from the upper edge of the second beam to the upper edge of the beam placed on the ridge. The resulting size will be considered calculated to determine the step of the lathing on the bottom slope of the roof.
- The step of the crate of the slope is measured along the upper edges of the nailed beams, depending on the slope of the slope.
As for complex multi-pitched roofs, the step of their lathing is calculated separately for each slope:
- With slopes of slopes less than 22 degrees - the step of the crate will be 31.2-32 cm.
- With slopes of slopes within 22-30 degrees - the pitch of the crate will be no more than 33.5 cm.
- With slopes of slopes over 30 degrees, the pitch of the crate will be no more than 34.5 cm.
Consider the implementation of such calculations on specific examples:
- The measured distance along the upper faces of the second and ridge bars was 789 cm. At the same time, the slope angle of this slope is 20 degrees. How many rows on the slope will be necessary and sufficient?
By dividing the distance between the bars (789 cm) by the value of the maximum step for an angle of 22 degrees (32 cm), we get the minimum value for the number of rows of crates at 24.6.
Dividing the distance between the bars (789 cm) by the value of the minimum step for an angle of 22 degrees (31.2 cm), we get the maximum value of the number of rows of the crate at 25.2.
In other words, you will need to break down the roof slope into 25 rows. In this case, the step of the crate will be equal to 31.6 cm (789/25).
- Let's take another example. The distance between the bars remains unchanged - 789 cm, the slope of the roof slope is now 27 degrees. Find out the required number of rows of crates.
By dividing the distance between the bars (789 cm) by the value of the maximum step for an angle of 27 degrees (33.5 cm), we get the minimum value for the number of rows of crates at 23.6.
Dividing the distance between the bars (789cm) by the value of the minimum step for an angle of 27 degrees (32cm), we get the maximum value of the number of rows of the crate at 24.6.
That is, the ramp should be divided into 24 rows, and the crate step will be 32.9 cm (789/24)
Advice! In order for the roofing material to be used as economically as possible, it is necessary to calculate the minimum number of rows with the maximum allowable step values for the specified slope of the slope.
Continue the installation of lathing for flooring from metal tiles as follows:
- The markup obtained in the calculations of the step is applied to the counter-lattice. In order to achieve greater marking accuracy, marks are applied in the plane of the counter-lattice, starting from the upper edge of the second beam in the direction of the beam mounted on the ridge. The step size is left unchanged along the entire length of the counter-lattice structure.
- The distance is measured along the upper edges between the second and ridge bars strictly along the extreme bars of the slope counter-lattice. If the dimensions on the right and left sides do not match, this means that the second and ridge beams are not parallel to each other. Since the pitch of the roof eaves is constant across the entire width of such a slope (the first two beams must always be parallel), the second beam cannot be used to adjust the distance on the right and left sides. The ridge beam must also remain parallel to the line of the ridge.
- The leftmost (32.4 cm step) bars of the counter-lattice.
- The corresponding marks of the right and left beams are connected with coloring lacing, and lines are beaten off on each beam of the counter-lattice for further stuffing of the lathing beams.
- In this case, the lathing beams are fan-shaped, however, the metal tile laid on them will visually present parallel rows, while hiding some oblique angle of the roof slope.
This is how the crate is mounted under the metal tile: the video presented on the Internet will help you deal with all the nuances of the process.
A similar method of marking and installing the battens is recommended for use with the correct geometry of the roof slope in order to ensure high accuracy in marking the rows, and in order to eliminate the curvature of the battens of the batten.
Lathing for Monterey metal tile and other common types of tiles is carried out in accordance with the specified step.
Advice! Further stuffing of the crate may require lining bars or slats of the required thickness under it to level the slope plane.
How to calculate the step of the lathing of a triangular slope
- To mount one or more tile segments on the upper row of a triangular slope, cut off a piece of the batten 12-14 cm long.
- It is fixed with self-tapping screws or galvanized nails to the counter-lattice in the upper segment of the triangular slope at a distance of about 5 cm from the point of their intersection. The specified length may vary depending on the location of the counter-lattices and the angle of the hip.
- The pitch of the crate is calculated in the same way as for a rectangular slope.
Having made the right frame for the metal tile, you will ensure the possibility of easy and comfortable laying of the roofing.
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