Flat Roofs

Flat roofs are a cheap alternative to a more common pitched roof design, as they use fewer materials to cover the same span of roof. Flat roofs also allow a green roof to be incorporated onto the flat structure.

To ensure a flat roof functions properly, it must have a fall to shed rainwater. A fall can be constructed using firring strips or tapered insulation. The most traditional covering for a flat roof is roofing felt. Roofing felt is made from a mixture of asphalt, bitumen and polyester and is nailed and glued down to the roof using felt adhesive.

Advantages of flat roofs

• Frees up internal space

• Quicker, easier and cheaper to construct than a pitched roof

• Requires less material to cover the same span

• Easy to repair and maintain

• Durable

• Easier to achieve planning permission compared to pitched roof where there is a height restriction

• Depending on personal preference, could be seen as more visually appealing compared to a pitched roof, due to minimalist, sleek appearance

Disadvantages of flat roofs

• Lack of drainage compared to pitched roof

• Vulnerability to water ingress if not properly sealed

• Shorter lifespan compared to other roof structures

• High repair costs

• Difficult to insulate without adding height to the roof / reducing the room height, potentially resulting in an unstable internal temperature

• Depending on personal preference, could be seen as less visually appealing compared to a pitched roof

• Fewer material options compared to a pitched roof

Key Words

Fall

A small slope that the roof is constructed on to drain water off the surface.

Firring Strips

Battens cut at an angle and placed on top of the roof joists.

Tapered Insulation

A fall cut directly into the roof insulation.