There are several choices when it comes to roof coverings, and these are available at a range of prices. The pitch and construction will also affect what options of covering material are available to you, so it is essential that you factor this into your budget before making any purchases.
Bituminous roofing felt, to go under tiles, can cost from as little as £1 per m² and will temporarily waterproof the building before the main covering is applied.
The roofing team will add their battens, and often counterbattens, immediately as the felt is prone to tear in high wind. The horizontal battens will be set at the appropriate gauge (spacing) to suit the tiles being fitted.
A breathable felt is likely to cost upwards of £1.50 per m² but, if the manufacturer can demonstrate its breathing credentials, then this can save you some other hidden costs in creating permanent airflows.
My preferred detail is to include a sarking layer on top of the insulation, which is common practice in Scotland. This is usually a 12mm or 15mm breathable timber sheet material fitted directly on top of the rafters.
It provides incredible additional strength to the roof, upon which a breathable felt is laid, followed by a counterbatten from eaves to ridge and finally the perpendicular tile battens.
Some builders do not give enough thought to the final choice of roof covering and, given that usually 25-40% of your elevation is roof, this is vital. Shallow pitches will eliminate the possibility of using slate or plain tiles but for pitches in excess of 36° almost all material options are available.
The cheaper products start with concrete, which can be manufactured as large interlocking tiles or small plain options.
A fully installed solution including the felt and battens, will cost circa £28-£35 per m² (plan) depending on type and pitch. By comparison a plain handmade clay tile is going to cost £80-£100 per m² with a whole raft of options in the middle on a sliding scale.
For those looking at slate, the really beautiful Welsh or Scottish material carries a premium at £100-£120 per m². Imported Spanish or Brazilian slate costs a little less at £60-£80 per m².
It’s obvious that this is an area for major budgetary debate, with most speculatively built properties heading straight to the concrete products while, those intending to stay longer in their homes are more willing to invest in creating a superior impression.
Don’t underestimate the plethora of options that go with the roof covering specification, some of which enhance both aesthetics and performance.
At the ridge your options include wet or dry installations and, dependent on the use of your attic, the need for vented ridge tiles.
Prices start at the lower level for hip tiles (similar to the ridge) although bonnet hips or cut mitres look so much nicer but inevitably cost more.
In the valleys you can use fibreglass trays, lead sheet or most pleasing of all (but again the most expensive) swept valley tiles.
At the eaves, where your roof overhangs the gable, there are traditional and modern detailing options. At soffit level, some designs lend themselves to open rafter feet, which means more work for all your trades but can make a building look thoroughly authentic.
It’s impossible to cost all of the options for you within the scope of a short article. Suffice to say that if you’re at the stage of planning your roof then these are some of the areas you should explore so that you can make an informed selection.
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