In accordance with BS5534 the laps of a roofing underlay can be restrained in 3 ways:

1. Restrained with an integrated or external tape.

2. Restrained with a ‘fly’ batten.

3. Restrained using the existing tile/slate batten line. The most cost-effective and quality-assured way of achieving this is by installing a roofing underlay with a double integrated tape system.