A flat roof is not quite as its name suggests, needing a small slope – or pitch – of a few degrees so that water can easily drain away.
And although its structure is simple – a waterproof layer, sometimes with a timber sheet underneath, that sits on ceiling joists – important calculations have to be made to ensure the weight of the covering, and any snow, can be supported by the beams, if not the roof could split and leak, needing flat roof repairs. This means Building Regulations approval is essential when carrying out flat roof repairs or building a new roof.
A big advantage with this type of roof is that the building it covers can be any shape and the walls don’t need to be parallel and perpendicular to each other, making it appropriate in many instances.
In Britain, flat roofs are commonly used for comparatively small domestic structures like extensions and garages.
A traditional covering of felt works well, providing all water flows away and no pools are formed, otherwise the roof is likely to sag. Incorrectly installed roofs can lead to flat roof repairs sooner than you’d expect.
Use of rubber, fibreglass or synthetic polymer is increasingly popular because these materials are less likely to allow water to collect and can often be applied as a continuous membrane, which reduces the likelihood of leaks.
While relatively inexpensive compared with a pitched roof, your choice of covering will influence the cost. Those with a larger budget who are after a sharp, distinctive finish may prefer to consider a metal option.