Ridges

How is the correct Angle Ridge Tile selected for a roof?

The correct selection of Angle Ridge Tile for a roof is made by calculation. Add the rafter pitches each side of the ridge and then deduct from 180º. Add to this figure twice the difference between rafter pitch and tile pitch. The angle of the ridge tile should be the same or slightly smaller than the answer, e.g. on a 30º pitched roof using Mini Stonewold tiles the angle ridge tile should be 180º - (30º + 30º) + (5º + 5º) = 130º. In this case a 120º angle ridge tile should be used being the nearest size smaller than 130º.

How should Rosemary ridge tiles be laid with Dry Ridge?

During the firing process clay ridge tiles can become slightly larger at one end than the other. On a mortar bedded ridge this is unimportant as it is compensated for by the mortar. However with dry fixed ridge the ridge tile sits in a profile filler unit, which has no adjustment. The variation in size from one end of the ridge to the other shows as a step in the ridge line. The plate that holds the ridge tiles may not lie perfectly flat. The tolerances permitted in BS EN 1304: 2005, Clay roofing tiles and fittings, are such that this may occur. The solution is to 'top and tail' each ridge tile, i.e. fix large ends together and small ends together.

Can Gas Flue Terminals be used for coal effect gas fires?

Gas Flue Ridge Terminals are licensed with British Gas for use with appliances with a maximum output rating of 60kW. The Gas Flue Ridge Terminal must also be connected to an 'R' type adaptor - available from metal flue liner specialists - which converts the circular flue to the rectangular outlet of the ridge terminal. The adaptor, available in 100 mm and 125 mm diameter, is bolted to the underside of the ridge terminal with a flue gasket fitted between them.
Whilst Gas Flue Ridge Terminals are suitable for most boilers, gas wall heaters and back boilers, they are not compatible with coal effect gas fires. These generally require a larger flue diameter than 125 mm. This is because the temperature of the flue gases is lower than for other heating appliances and they need assistance from the stack effect to draw them out. It is always advisable to consult British Gas with any queries regarding the compatibility of gas-related products.

What fixings should I use to mechanically fix ridge tiles?

Mortar bedded ridges can be mechanically fixed to comply with BS 5534: 2003: Code of practice for slating and tiling by using wood screws and clamping plates to fix universal angle or half round ridge tiles to a ridge board or ridge batten. The wood screws and clamping plates are available in packs of six. Specify product code 9566 for half round ridge tile plates, 9567 for universal angle ridge tile plates and 9584 for wood screws.
It is essential that the ridge board or ridge batten is positioned to provide a minimum of 15 mm penetration of the wood screw. For trussed rafter roofs where no ridge board is present additionally specify product code 9447 for packs of six batten fixing straps.

How close can Ridge Vent Terminals be placed together?

It is not possible to place Ridge Vent Terminals immediately next to each other when using Dry or DryVent Ridge as it is essential that the ridge batten spans at least two rafters to ensure its stability. The closest the Ridge Vent Terminals should be placed together is every other rafter spacing. At 450 mm rafter centres it may be possible to space the terminals at 900 mm centres without the need to cut ridge tiles. At 600 mm rafter centres, 150 mm pieces of ridge tile must be cut and fixed between the terminals.