Flat Roof Slope Design

According to bs 6229 bs 8217 flat roofs should be designed with minimum falls of 1 40 to ensure a finished fall of 1 80 can be achieved allowing for any inaccuracies in the construction.

Flat roof slope design.

Flat roof design guide. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. Flat and low sloped roofs look striking on a wide variety of architectural models especially on contemporary house designs. This is the basis for calculating the angle which is approximately a 1 19 degree slope.

Many slope in several directions like squashed hip roofs toward scupper holes that connect to downspouts. This modest slope can be achieved in a number of ways. This is necessary for allowing water to run off of the epdm membrane surface and towards an appropriate drainage system. Some local codes take it a step further allowing a slope of only of an inch per foot.

In fact many residences have sections of flat roof on porches balconies garages and room extensions which appear so attractive. This may make it less ideal for rainy or snowy climates. Flat roofs are built with a slight pitch of at least 1 8 per foot so water can drain either to centralized drains scuppers or a gutter system. Contrary to its name a flat roof isn t actually flat.

Flat roofs are typically designed with a pitch of 10 degrees or less. But this slope doesn t need to be extremely steep and when covering a large property the angle of the flat roof. Despite the name all flat roofs need to be slightly angled in some direction. The most important thing to know about a flat roof says tom is that it s not flat to prevent water from pooling and eventually invading the home flat roofs are always built on a slight incline at least 1 8 inch per foot.

It takes the manufacturer s recommendations the unique conditions of the roof as well as the skills and the expertise of the installer to arrive at the right slope. Flat roof slope minimum according to the international building code the typical built up flat roof that uses tar or asphalt goes by the guideline that for every foot 12 inches of a flat roof a minimum of inch must step up or down. If your house s architecture is modern then a flat roof home design is basically expected. According to the international code council the minimum slope for water runoff is inch per 12 inches.

First you have to determine how shallow a slope you can get away with.