Most roof tiles are designed for pitches greater than 20 degrees, using a standard tile on a shallow roof can lead to water penetration that will be costly to repair. Most buildings are constructed with a steeper pitch but if you find yourself working on a roof lower than 15 degrees then there are some specialist tiles you should consider using.
Redland Regent is a popular roof tile and is used on thousands of properties in the United Kingdom, it can be specified for roofs as low as 12.5 degrees which makes it a favourite for shallow roofs. The tile will blend in well with any existing tiles to surrounding buildings as it is made from concrete with a standard choice of colour finishes.
Marley Wessex is made from concrete and unlike the Redland Regent it has a near flat profile. It can also be specified for roofs as low as 15 degrees.
Forticrete Centurion is another concrete tile that is designed for shallow roofs, this time as low as 10 degrees although there are some requirements that must first be met, the roof should not have any valleys and be of limited length.
Decra Classic is unusual as it is made from metal with a coated finish, these metal sheets do look like traditional tiles but can be installed to roofs as low as 10 degrees. They should be secured to the roof rafters with specialist fixings and it is not possible to walk on them once they are laid as they will dent easily.
Flat roof felt or rubber sheets – if the roof you are working on has a pitch below 10 degrees then you should consider laying bitumen based felt or rubber (epdm) sheets onto the structure.
Tips to prevent water ingress – When working on a shallow roof there are several points to note:
- Do not allow rainwater from any above guttering to empty on to the roof
- Avoid valleys and roof rafter lengths greater than five metres
- Never use a tile that is not specified for than pitch
- Use smooth surfaced tiles and not granular tiles (reduces water capillary action)