That's right — flat roofs usually aren't flat. A so-called flat roof may look horizontal but often has a slope of at least 1/4 inch per foot. Quick language lesson: Pitch and slope are terms used to describe the angles of your roof. What pitch should a flat roof have?
Generally, minimum slope for water to run off is 1% (1/8" per 1'). However, minimum slope for a flat roof by building code here is 2%. (1/4" per 1'). You have more than enough slope for your roof, however you will likely need some sort of membrane roofing since it is very low slope.Feb 18, 2013 What is the minimum fall for a flat roof?
It is generally considered good practice for flat roofs to be designed to clear surface water as rapidly as possible. According to BS6229 & BS8217, 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 Falls & Drainage Provision in Designs - Bauder Can a flat roof be pitched?
There are several ways to convert a flat roof to pitched. The typical way is to remove the existing roof and add new framing to the home that create a pitched roof over the old flat roof area. On houses, new pitched roofs typically are supported by the exterior walls, as with standard sloped-roof construction.
Home Flat Roof Conversions - Shingle Masters
