Installation of metal roofing

1. General Provisions

Sheets of metal tiles are supplied according to preliminary declared dimensions, which are installed as a result of careful measurements of the roof slopes. The main size is of decisive importance – from the cornice to the ridge. When measuring, it must be borne in mind that the bottom sheet of the metal tile should have an overhang of about 40 mm.

Taking into account the standard useful width of metal tiles of 1100 mm, you can calculate the required number. If the length of the slopes is more than 7.5 m, it is advisable to break the sheets into two or more pieces with an overlap of 150 mm.

Metal roof structure

1. Cornice strip
2. Sheathing board
3. The falling bar of the counter-lattice
4. Waterproofing film
5. Rafter
6. Skate
7. Sheets of metal tiles
8. Ridge seal
9. Ridge plug
10. Wind board
11. Downpipe
12. Pipe holder
13. Gutter
14. Chute holder
15. Snow barrier
16. Endovaya outer
17. Valley inner

Is the roof even

Before starting installation, check the geometric dimensions of the roof. The diagonals of rectangular slopes must be of the same size. If there is a small difference in size, defects can be corrected using separate elements.

The minimum permissible angle when installing metal roofs is 14 degrees.

If the angle of inclination of the slope is less than 14 degrees, then the overlap of the sheets of metal is done in two waves.

2. Steam and waterproofing

On the cold bottom surface of the metal tile, moisture condensation occurs in the warm air, which is understood from the interior. This leads to the formation of mold, moistening of the rafters and battens, freezing of the roof and deterioration of the interior decoration. To combat such phenomena, it is necessary:

• to carry out thermal insulation of the interior from the roof;
• protect the thermal insulation from below from moisture inside the house with a vapor barrier film;
• protect the insulation from above with a waterproofing film;
• provide good ventilation.

The sheets of the vapor barrier film are placed under the heat-insulating material and are tightly overlapped with gluing with adhesive tape.

For additional protection of thermal insulation from external moisture, a waterproofing material is laid on the rafters. Layers of waterproofing film are spread horizontally from the eaves to the ridge with an overlap of 150 mm and a sag of the film between the rafters of about 20 mm. The side of the film with the colored stripe on the edge should be facing out.

It is not allowed to turn the film over. To ventilate the inner space between the film and the thermal insulation, leave a ventilation gap of at least 40 mm, and the under-roof carpet of the waterproofing film should not reach the ridge by about 40 mm.

1. Waterproofing film.
2. Perforated ridge seal.
3. Additional sheathing boards under the ridge.
4. Ventilation gap in the waterproofing film.

Ventilation is the main condition for ensuring a reliable roof structure and base under the roof. For ventilation, it is necessary to ensure the possibility of an unobstructed passage of the air flow from the eaves to the ridge. Ventilation is carried out through:

• the gap between the eaves and the metal tile;
• specially left air gaps of 50 mm in the eaves filing;
• ventilation gap between the waterproofing film and the ridge;
• perforation in the ridge seal.

3. Lathing

Falling bars 25 x 50 mm are nailed to the rafters on the laid waterproofing material, and antiseptic lathing boards 32 x 100 mm with a pitch between them 350 (400) mm, corresponding to the pitch of the metal tile (350 mm – for the Monterrey profile, 400 mm – for the “Maxi” profile). The bottom batten board should be about 17 mm thicker, and the distance between the beginning of the first and the middle of the second batten board should be 300 (350) mm. If the distance between the rafters is more than 1000 mm, the boards for the sheathing must be taken thicker.

In order for the ridge bar to be well fixed, two additional boards are nailed under it on both sides. These boards are covered with a strip of waterproofing material and cover the ventilation gap in the waterproofing film.

4. Cutting the profile

Profiles can be cut: with an electric nibbler, a jigsaw, a circular saw with carbide teeth, hand scissors for metal, a hacksaw with fine teeth. Cutting with an abrasive wheel is prohibited, since hot chips falling on the plastic coating burn through it, and this leads to accelerated corrosion at the cutting points.

5. Profile installation

Before installing the profile, a cornice strip is nailed along the eaves of the roof. Lower valleys are installed in appropriate places.

The metal tile is attached to the lathing boards with self-tapping screws 29 – 38 mm long, for screwing in which you need to have a drill with a reverse, a brace or another similar tool, as well as an 8 mm socket. Installation usually begins with the lower right roof sheet, fixed in the upper right corner with one self-tapping screw: 2-sheets are laid, fastened together with self-tapping screws along the top of the overlap wave, the resulting flat bottom edge is aligned strictly along the cornice with a 40 mm overhang, after which the sheets are finally fixed. Alternatively, the following fastening method is recommended: fasten the sheets with self-tapping screws in a checkerboard pattern through one wave. The joint of the upper and lower sheets is fixed with self-tapping screws through the wave. Self-tapping screws are placed in the deflection of the wave (unlike slate). The side overlaps of the sheets are fastened with self-tapping screws to the top of each wave. Number of self-tapping screws 6-8 pcs. per square meter.

After installing the sheets between the ridge and the metal tile, a seal is placed with previously released ventilation holes, then the ridge is attached with ridge self-tapping screws 4.8 x 80 with a step of 300 mm (through the wave). The ends of the metal roof ridge are closed with plugs on self-tapping screws. In the places where the valleys are installed, decorative external valleys are installed on top, and at the ends of the roof – wind boards, which are fastened with self-tapping screws.

If at the end of the roof the cut of the metal tile falls on the lower bend of the profile wave, then the edge of the sheet must be bent by about 30 mm to prevent water and snow from entering.

To prevent snow from rolling over the entrance to the building at a distance of about 650 mm from the cornice, a snow barrier is attached with ridge screws.

Attention! You should move on the metal tile in shoes with soft soles, stepping into the deflection of the wave in the places of the crate.

6. Storage of metal tiles

A stack of metal tile sheets in their original packaging must be laid out on level ground on beams 20 cm thick in 0.5 m increments. The sheets must be shifted with slats if the metal tile will be stored in a rack for more than 1 month.