Roofs covered with sheet metal are exposed to unfavorable phenomena consisting in settling of moisture on the underside of the sheets, condensation of water vapor, flowing it down the plate to the line of the battens, and even dropping off. Their scale depends on the degree of relative humidity in the rooms, type of attic insulation, the efficiency of ventilation of the lower plate plane. Due to the influence of these phenomena on roofs intended to be covered with a corrugated sheet, it is advisable to use double roofing.

The lower plane of the roof drainage, also called windproofing, it can be made of one layer of insulating tar paper, not glued overlaps or made of windproof foil, known as the pre-mating film, laid on full formwork. The sheet should be supported and fixed on wooden laths nailed to the counter battens.

Patches due to the high bending stiffness of the sheets (for example. profile T-55) can be arranged at a large spacing exceeding 200 Cm. For sheets with a low crease (for example. profile T-18) the maximum distance between the years is approx 100 into 120 Cm.

Roofs covered with corrugated sheets require careful flashing on the edges of the roof slopes. If the sheet folds are high, it is necessary to attach a drip strip led above the gutter under the metal sheet. On the ridge side, the ends of the corrugated sheet in the groove should be bent upwards as much as possible and covered with a two-piece ridge sheet before assembly.. It should be covered with a cover ensuring proper ventilation of the space under the sheet. The ridge plate should overlap the corrugated sheets at least in length 300 Mm, after the incision, it must be bent into furrows
and seal. The processing of the side walls of the board at the edge of the roof slope should be made of sheet metal placed on top of the corrugated sheets and overlapping the crests of the two folds. It should be finished with an eaves tooth.

Eaves solution for a trapezoidal sheet roof: 1 – corrugated sheet of the roof covering, 2 – inserts made of hard polyurethane foam , 3 – soft polyurethane gasket, 4 – sheet metal of the gutter strip, 5 – gutter, 6 – mesh inlet to the air gap, 7 – gutter hook embedded in the eaves board, 8 – front surface of the counter-batten is impregnated, 9 – flashing of the faceplate, 10 – front board, 11 – krokiew, 12 – windproofing 2 x papa, 13 – ventilated gap under the cover, 14 – eaves board, 15 – sheet stiffening the gutter flashing.

Flashing from the ridge side: 1, 2 – as in fig. above, 3 – years under the corrugated sheet, 4 – ridge flashing with a cover.

Flashing of the side edges (peak) roof slope: 1 – the corrugated sheet of the cover, 2 – steel spacer, 3 – a patch for a corrugated sheet, 4 – contracted, 5 – windproofing, 6 – screw with washer, 7 – sheet metal screw, 8 – roof edge wind board, 9 – eaves tooth, 10 – flashing of the wind board.

The greatest difficulty for contractors is to process the baskets properly, roof chimneys and hatches, especially in low-slope roofs. In the baskets located, as a rule, at a certain angle to the sheet folds, the same flashing is performed as in tiled roofs.. In the case of wider chimneys situated perpendicular to the slope of the slope, it should be made from the side of the water flow, covered on both sides with a sheet, high fender boots with flat sheet processing in the 7 line of the Kozubka ridge. Snow slides easily from the sheet metal roof, which can cause the hooks to deflect’ gutter. Therefore, on top of the folds near the eaves line, it is worth installing a snow barrier made of an inverted V-shaped sheet metal.. Properly made coverings made of a coated corrugated sheet require little outlay during the service life and are therefore eagerly used by many investors..