Before the 2014 revision of the British Standard BS 5534, operatives installing single lap roof tiles would leave a few tiles unfixed, then push them up so they could walk up the roof on the timber battens. This access option is now not available because the latest revision to the Standard recommends that, as a minimum, all tiles should be fixed with nails or clips.
The NFRC has published guidance for its members, with some of the key points summarised here.
Using perp lines
During their installation, single lap roof tiles should be fixed from right to left with a ‘perp line’ to ensure that the vertical start line of the roof coverings is straight, to account for any difference in length between the dimensions of the ridge and eaves during the installation.
Ideally perp lines should be struck after every third tile so that the horizontal shunt (play) in the tile sidelock can be utilised to keep the tiles running straight which will ensure that any cutting is minimised, and where cutting is required, all the cuts will be of equal size. However, note that there may be regional variations to setting out the perp line.
Eaves vent system and underlay support tray
If possible, these should be installed after the roof is loaded out to prevent damage caused by foot traffic during the loading process. If this isn’t possible then the rafter roll should be installed prior to loading followed by the underlay support tray and over fascia vent after loading.
Position of the operative on the roof
The finished roof covering should be installed by operative while kneeling or standing on the timber roof battens rather than on the completed newly installed tiles. The operative’s foot position should be where the horizontal roof batten attaches to the roof truss. At no point should the operative stand mid-span between roof trusses. Roof works should continue around the project working from right to left and any detailing should be completed as works progress (where reasonably practicable).
If the position of the roof vents is known, they should be installed at the same time as the roof coverings, since retrofitting them at a later date would require the removal of the finished roof tiles, which may cause unnecessary damage to adjacent tiles and their fixings.
When installing any leadwork (or equivalent) soakers and flashings, all chases into masonry or brickwork should be cut and installed prior to the finished roof coverings being installed. This ensures that operatives are working off the timber battens with only the final dressing being undertaken once the finished roof has been completed.
Dry fix ridge system
Lay the rollable weathertight membrane centrally along the ridge batten (if required) and tack with a staple or underlay nail to the ridge batten. Once the membrane has been dressed and stuck to the profile of the roof tiles, then the ridge tiles should be installed as the works progress with the operative working from the leading edge of the installation off the timber battens.
This should be completed off a safe working platform, scaffold or ladder so that access onto the completed roof coverings is not required.
Maintenance and repair
Repairs should be carried out in a kneeling position or from crawling boards or roof ladders, suitably packed with a solid foam type product (such as insulation board) or other compressible material. This spreads the load so as to avoid point contact on the tiles. Any access equipment utilised should be properly supported and anchored to prevent slippage or tipping.
Stripping off old roofs
Remember that tiling battens deteriorate with age and should not be used as footholds unless they have been inspected by a competent person who has confirmed that they are strong enough. If in doubt, they should be regarded as fragile.
It is unsafe to work or handle materials in windy conditions. The HSE recommends that tiling work should cease if the mean wind speed reaches 23 mph (gusting to 35 mph or over) and if handling rolls of underlay the limit reduces to 17 mph (gusting to 26 mph or over).
This information is taken from a new illustrated Guidance Note, which will be available to download shortly.