Garage Roof Advice PLEASE!

12 Oct 2007
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United Kingdom
I have a shot corrugated cement/asbestos garage roof. I have checked with council and can take it to them for disposable. The garage roof has a pitch, not sure what the pitch is, but looks pretty standard upside down V shape garage roof! There are 2 lengths of metal perlins for each side of the roof, I have already bought some metal to install another length of perlin on each side of the roof, making three perlins for each sheet of material. I was thinking of using bitumen corrugated sheets from Wickes ( but was worried that they are fairly flexible and may need more support. If they start to sag and end up leaking, then it will be a disaster. Am I being paranoid or should I use a cheap wood board first and then fix the bitumen corrugated sheets to this? If so what kind of wooden sheet should I use? Are the bitumen corrugated sheets the correct material or are they just cheap and nasty? I want something that will last and have a budget for material of around £500

Please can you give me some advice on how you would proceed with a project like this with this budget. I will update when I'm at home with some measurements of the length of garage and the spacing of the perlins and the length of sheet required. How can I easily measure the current pitch?

Thanks in advance.
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No need to know pitch, just measure the old sheets to find out how much length you'll need. The bitumen sheets are fine, you can pick up a leaflet instore that will tell you all you need to know about installation. Easy peasy.
I was told that depending on the pitch, these sheets (being flexible) may not be suitable. I was told I may need to board the roof first. I was wanting confirmation of if I did to board first or just fix the sheets to the metal perlins? I don't want the roof to sag and leak. If I did board the roof first, what kind of wood board would be best? Do I need to board first?
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Only likely to cause a problem with very shallow pitches. It certainly won't hurt to board out first though, for a stronger roof all round. Use roofdeck osb3, or wbp plywood.
If you look on the wickes site you can download a pdf explaining the support needed and purlin distances etc

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