Flat Roof Drainage Requirements

Size horizontal storm drainage piping.

Flat roof drainage requirements.

Along with the benefits of a flat roof come unique challenges. Select number of roof drains and calculate the roof area sloped to each drain. To design a sloped or flat roof drainage system we need to know the anticipated maximum rainfall rate and the flat or projected roof area. Take the roof s total square footage and divide by the total square footage handled by one drain.

We describe online roof drainage requirements calculators pertinent plumbing standards a table approach to looking up roof drainage. What is a flat roof. 6 24 2014 david howard aia said. If you re thinking of installing a flat roof it s important to make sure you are up to date with all the rules and regulations before you begin with a new flat roof construction.

Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally. They are common on extensions garages and commercial buildings. It is a requirement of building regulation part h that adequate provision is made for rainwater to be carried from the roof of the building. Flat roofs are an often lower cost and easier to install alternative to traditional pitched roofs.

The best type for the application depends on several factors such as the size and slope of the roof the desired appearance and how much regular maintenance the drain system might need. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. Roof drains for flat or low slope roofs come in a few standard types. Interior drains work just like the drain in your shower or sink.

Flat roof inspection checklist. The most critical of these issues is the flat roof drainage systems. Any water should have evaporated by this time. Cities based on inches per hour that may fall during a storm of one hour duration and a 100 year return period.

Size vertical storm drainage piping. Leaving your flat roof without a drainage system will greatly increase the risk of these issues. These drains are placed in areas of the roof that collect the. 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.

The result is the number of drains needed. Fitting the roof with one of the following systems to ensure proper drainage will help keep it protected. This article describes several methods for determining the drainage capacity required to safely drain water off of building roofs whether from rainfall melting snow or a combination of those water sources. In normal circumstances wait until 48 hours after a rainfall to clean and inspect the roof.

What is the general area of a flat 1 4 1 0 slope single ply roof for each roof drain ratio for the number of roof drains roof area. Roof drainage requirements specifications. Appendix b in the ipc provides rates of rainfall for various u s. Calculate drains needed.

If it hasn t that s a sign of a problem with roof drain parts or the drainage system.