How To Slope A Flat Roof

This solution is perfect for homeowners looking for the easy option for adding slope to a flat roof property.

How to slope a flat roof. Generally such roofs have a pitch ranging from 1 2 12 to 2 12. Creating a positive slope roof is traditionally done by installing rigid board insulation such as xps or polyiso on flat or low sloped roofs. To put it in perspective the angle of this slope would be around 30 degrees. What is the most appropriate angle for flat roofing.

Low pitched roofs are generally difficult to maintain and you need special materials to prevent leaks. If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. 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.

Flat roofs should have a minimum slope to allow water to run off. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. There is a problem with using these materials though. This means that the rise of the slope goes up or down 8 inches for every 12 inches.

The first is using tapered foam insulation on top of the roof trusses. Eventually water penetrates the building. However in some cases building owners hire contractors that poorly designed the roof. Unlike sloped roofs flat roofs are susceptible to ponding water.

There are two ways we typically use to create low slope on flat roofs. The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches. Flat roofs which aren t perfectly flat require a small slope to allow for water runoff. An example for a steep sloped roof is 8 12.

Water that stays on a flat roof after it rains will weaken the material over time. 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. Xps and polyiso are available in boards that are no more than a few inches thick.

Notes to the table above.