Redland emphasises the importance of batten straps in mortar bedded ridges
The improper installation of mortar bedded ridges continues to be a major issue plaguing the roofing industry, and one that can cause serious damage to the entire roof.
The most common installation error is the misuse, and in some cases the complete abandonment, of batten straps when fixing the ridge batten to the apex of the roof. It is crucial that all batten straps are nailed to the rafter before the top tiling batten is put in place in order to effectively secure the ridge.
In an effort to save time, some roofing contractors are disposing of batten straps entirely, instead relying entirely on the mortar to hold all ridges in place.
Should this mortar fail at any stage in the lifetime of the roof, all of the ridges fixed into the unsecured ridge batten could slide off the roof together, severely damaging other roof tiles and potentially injuring passers-by below.
The consequences of this poor practice are potentially much worse than a single tile failure. What’s more, it fails to comply with the current BS 5534 code of practice, which states that mortar alone cannot be used to fix ridges and hip – so even if mortar is used, the ridges and hips must also be mechanically fixed.
In an effort to simplify the installation process, and help contractors comply easily, Redland has delivered a way to mechanically fix mortar bedded ridges and hips by using its new Mortar Bedded Fixing Kit. The kit enables the installer to maintain a traditional mortar bedding aesthetic whilst still complying with BS 5534 and the NHBC’s secondary fixing guidelines.
While dry-fix solutions are preferred, mortar bedding may still be an aesthetic requirement in conservation areas and the Mortar Bedded Fixing Kit is simple to use and provides contractors with all of the components required to mechanically fix mortar bedded ridges and hips.
Further information can be found on the Redland website at www.redland.co.uk/ridges
Step 1: Ridge/Hip Batten
Lay underlay to the apex of the roof and batten the roof in the normal manner. Do not fix the top tiling batten at this stage. Use a combination of 38mm x 25mm softwood battens to achieve the correct ridge batten height and nail them together at the same centre as the rafters with 65mm nails.
Step 2: Form the Batten Strap
Form the Batten Straps so that they can wrap easily around the ridge battens.
Step 3: Fit the Batten Straps
Position the ridge batten along the centreline of the apex. Nail the Batten Straps to the rafters using the two 30mm x 2.65mm annular ring shank nails provided.
Step 4: Cover the Ridge/Hip Tree
Cover the ridge tree with underlay and fix the top tiling batten in the usual way.
Step 5: Tile the roof
Tile the roof in the normal manner ensuring compliance with your manufacturer’s fixing specification.
Step 6: Apply mortar to the roof
Apply mortar to the roof in the traditional way and place the ridge / hip tile on the roof in the normal manner. Wipe away excess mortar with a damp sponge.
Step 7: Mechanically fix the tile
Insert the woodscrew through the clamping plate and embed it into the mortar joint between the tiles. Screw the woodscrew in, ensuring that it remains perpendicular to the roof. An alternative approved method of fixing the screw is to drill a hole in the ridge tile and pass the screw through it, creating a secure fixing.