Code of practice BS5534 spells changes for roofers

A new code of practice that details design standards, performance and installation of pitched roofs and vertical cladding using slates, tiles, shingles and shakes, as well as their associated components, has been published.

You have until February 2015 to start following the new standards outlined in the new BS5534 Code of Practice: Slating and tiling for pitched roofs and vertical cladding, which was published in August 2014 by the British Standards Institution.

Key changes that will affect you are

• Mortar alone cannot be used to fix ridges and hips. So, even if mortar is used, the ridges and hips must also be mechanically fixed
• Fixing requirements for roof tiles have been increased. All single-lapped tiles on a roof will now have to be mechanically fixed and perimeter tiles must now have a minimum of two fixings
• There will now be a single test for the measurement of the wind uplift resistance of underlays, which all testing bodies will have to comply with.

Ridges and hips - In future you are likely to be asked by building control bodies how you intend to meet these new requirements. Although you do not have to use dry fix systems, you will have to demonstrate how you can effectively fix ridge tiles when using mortar.

Fixing of roof tiles – This needs great care as there are a number of proprietary systems available, but beware as many of them are specific to particular makes of tiles. It will be up to you to demonstrate you have the correct fixings and numbers for the type of tiles you intend to use.

Roofing underlays – They are prone to stretching and ‘ballooning’ under wind load. This can cause the tiles to have greater wind loads applied to them than their design permits. The new standard for underlays will test against this issue. So be sure it has been tested to the new standard and clearly identified as being suitable for the site location and batten gauge in question.

The National Federation of Roofing Contractors (NFRC) is running a series of training courses to help you understand the implications of these changes. Contact Drew Beattie at NFRC for more information.