Experts Questions and Answers

Katie, thank you for your question. There are two main differences; The main difference between a flat roof and a sloped roof is in the way they are built. A sloped roof shed water, they are not watertight, you can think of them as an umbrella. Flat roofs use a waterproof membrane to protect the building, flat roofs act as a weather tight  skin. Both have the same purpose and that is to protect the building from the elements (rain, snow, wind) and to provide some architectural appeal. The second difference is in the slope which is the ratio of the rise over the run. The run is usually expressed by professionals as 12. A conventional slope is 4 in 12 and up, a low slope roof is 2 in 12 to 4 in 12 and a flat roof is 0 in 12 to 2 in 12.

I hope this answers your question Regards, Lily