diy epdm roofing

8 Aug 2011
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United Kingdom
Hi guys looking for any tips youve got on doing an epdm flat roof :confused:
We have a 12m square flat roof / balcony and it was built ventilated with no insulation, ive finally had enough of the enormous heating bills so im becoming a roofer for a week this summer :rolleyes:

The Plan is to lift the existing tiles and felt etc, lay 100mm of kingspan over the top of the existing plywood base, re board over the top of that and then apply the epdm.

My biggest question so far is how thick does the ply over the kingspan need to be? its not load bearing due to the ply thats already underneath but i dont want to stretch of puncture the rubber if the top layer of ply is to thin?

Thanks all any advice greatly received!
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Id use 18mm T&G OSB3 boards, that way you will have an even finish, ie no discrepancy showing on the joints.
If you are using it as a balcony lay walk way mats over the epdm.
I second the 18mm T&G OSB, it is sooooo much better than butt jointed boards, gives a very solid surface and cuts down massively on waste (oh and a lot easier to handle too)
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You wont need 18mm if this is being laid direct onto board insulation. 12mm will do. Just remember to lap all the joints between the ply/insulation/deck layers.

Having said that, T&G may be easier if you are DIYing

Spend money on all the propriatory plastic edge trims and gutter trims, as they are well worth it

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