Flat Roof Pitched Roof Detail

Roof deck providing the base for the waterproof membrane and in some cases the insulation.

Flat roof pitched roof detail.

Waterproof membrane to prevent water penetrating the structure and interior of the building. A flat roof isn t actually flat. This could mean flat roofs may not raise the same red flags they used to. If flat roofs are to work well they have to have a slope known as a fall to shed rainwater.

What pitch is a flat roof. The fall should never be less than 1 80 and preferably about 1 40. Although flat roofs are cheaper to build than pitched roofs they have a shorter life span. It appears to be flat but it needs a slope to allow the water to drain from the roof.

Many slope in several directions like squashed hip roofs toward scupper holes that connect to downspouts. The high end of the ply layboard will have a cocking fillet fixed to it so that it provides a kick for the bottom course of roof tiles. Cad details document name pdf dwg download all cad construction details 37 1 mb 3 4 mb mc01 identification of roof areas 694 kb 167 kb mc01a single layer underlayment 678 kb 302 kb mc01b double layer underlayment 711 kb 322 kb mc02 vent pipe flashing 626 kb 349 kb mc03 valley. Figure 20 8 shows the materials commonly used to frame a flat roof.

But now flat roofs often are constructed with fewer layers because of improved waterproofing technology. When a flatty joins a pitched at eaves level i e. Armourvalley or other materials like epdm pvc or tpo covering. For slopes less than 9 5 we cannot install roof shingles.

A flat roof usually consists of the following. Figure 20 9 shows how a flat roof could be repre sented on the roof plan. Definition of roofs slopes flat roof a flat roof is defined by having a roof pitch below 15 degrees or a fall of 1 in 40 and can comprise of different products pitched roof a pitched roof is defined by having a roof pitch above 15 degrees or above fall of 1 in 40. Flat roofs are hard to replace.

Flat roofs and pitched roofs exist side by side as equal partners. Often the flat roof has a slight pitch in the rafters. The flat roof is economical to construct because ceiling joists are elimi nated and rafters are used to support both the roof and ceiling loads. Can metal roofing be used on a low slope pitch roof.

Instead the roof must be done with a modified bituminous membrane e g. Some observers suggest it s harder to replace a flat roof than a traditional pitched shingle roof because of the labor required to remove its layers especially on older flat roofs. It has a slope of 2 3.