How To Slope A Flat Roof

The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches.

How to slope a flat roof.

Flat roofs should have a minimum slope to allow water to run off. Low pitched roofs are generally difficult to maintain and you need special materials to prevent leaks. 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. This means that the rise of the slope goes up or down 8 inches for every 12 inches.

In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. Notes to the table above. What is the most appropriate angle for flat roofing. Using modern cement screed mixes a professional flat roofer can fill dips and hollows quickly and level them or slope them rather to fill the low point and re create the surface of your roof.

Low slope roofs are from 0 to 3 12 in pitch. Flat roofs which aren t perfectly flat require a small slope to allow for water runoff. Water that stays on a flat roof after it rains will weaken the material over time. There is a problem with using these materials though.

If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. Some sources consider low slope to include 3 12 pitch roofs. Normally 1 80 0 72 is the recommended minimum angle for a slope and this is universal across the vast majority of flat roofing systems regardless of the materials that they incorporate. The second is to slope the roof trusses themselves this is done by the truss manufacturer.

This solution is perfect for homeowners looking for the easy option for adding slope to a flat roof property. Eventually water penetrates the building. Xps and polyiso are available in boards that are no more than a few inches thick. An example for a steep sloped roof is 8 12.

Generally such roofs have a pitch ranging from 1 2 12 to 2 12. However in some cases building owners hire contractors that poorly designed the roof. There are two ways we typically use to create low slope on flat roofs. Unlike sloped roofs flat roofs are susceptible to ponding water.

Creating a positive slope roof is traditionally done by installing rigid board insulation such as xps or polyiso on flat or low sloped roofs.