Dry roof valley help please.

22 Nov 2009
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United Kingdom
I'm fitting a grp valley and would like to keep the existing valley boards, but they are nailed on top of the rafters rather than set flush - so if the membrane is under the battens it will have to step up onto the board, is this ok? I think it will create a trough down the side of the board, also I would like to side nail the battens to the edge of the valley board but this will pierce the membrane - any suggestions appreciated, nice and simple- this is my second valley ever!


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If you are putting large concrete tiles on your roof then you won't be able to keep those valley boards as it will be too high.
Yes, I hadn't anticipated this so didn't have any OSB or ply available, fortunately the boards are in good nick for 90 years old so I've made a start on cutting and dropping them in flush:


Unfortunately I think I probably set the lay boards for the lap up of the flat roof at the bottom similarly too high and I don't want to peel off the EPDM but I think I can just about get away with that with a bit of jiggery pokery!

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