A flat roof is a roof that is almost, or completely even. Although flat roofs are termed as being ‘flat’ – these roofs are laid with a fall that makes sure rainwater can drain off the lower side effectively. Flat roofs are designed to have a minimum fall of 1:40 which results in a 1:80 fall once construction is finished.

Flat roofs are defined as roofs where the slope does not exceed 10 degrees from the horizontal. They are very often seen as a cheaper alternative to pitched roofing. However, the longevity of this roof type is far less than that of a pitched roof and lasts between 6 and 35 years – dependent on the quality of the roof covering and the structure/construction.

Flat roofs generally require a greater degree of maintenance – even more so if the surface is disturbed and damaged by people frequently walking over it. Flat roof drainage is historically not as effective as traditional pitched roofs and standing water (ponding) can be an issue if falls are not adequate.

Flat roofs do require more maintenance than a traditional pitched roof. This can happen even more so when the surface is damaged when people may walk over it. The drainage of a flat roof is not as effective as a traditional pitched roof and ponding can be a problem if the gradient of the roof is sufficient.  

The most common issues that you may encounter are:

• Alligatoring – The main sign that your flat roof needs replacing is alligatoring. Alligatoring is when the asphalt that is used to build your flat roof has lost its elasticity which causes it to crack and bubble much like the skin of an alligator.
• Leaks and moisture – The most common problem with flat roofs is leaks and moisture. These are issues that can be dealt with effectively if kept on top of. As the roof is flat, the water doesn’t have anywhere other than directly downwards. This means that any moisture may go into the roof itself and cause you further issues such as mould and fungus.
• Pooling water – Your flat roof may over time shift which means that it may not be as flat as when it was installed. This could cause water to pool in any divots or dips. Most materials are manufactured to hold up water. If you allow pooling on your flat roof, it is likely to deteriorate the exterior form of the roof which will shorten its life span.