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Shed Roof


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New member
17 Jun 2018
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Hi i am about to replace the felt which has torn, on my shed roof.
The shed is 16 x 10, and i'm using onduline as a replacement.
If i've measured right, the pitch of the roof is 20 degrees.
The shed structure is OSB sheets, which were replaced about 5 years ago.
My question is, if i just nail to the OSB , instead of fitting purlins as the installation guide recommends, what are the real problems that will happen?
it's not laziness, i just haveing mobility issues at the moment, plus at the back of the shed there's only a gap of about a foot, with a fifteen drop the otherside.
do you reckon i could get 5 years out of the roof, if i nail to the osb, given the pitch...



Established Member
1 Jan 2016
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I do not think any of us can give a definitive answer. I would say probably and quite possibly a lot longer, but how exposed is the site, how thick is the OSB, how long are the nails, are there any joists under the OSB, if the nails will penetrate the OSB can you bend the ends over? Why not use EDPM glued down although you would probably need help to get it onto the roof.

I have used onduline and it is better with OSB under it as it stops it sagging but I would nail through into the joists underneath. On exposure: I have had the pitched OSB/felt roof of a wendy house blown off, I refastened it with lots of screws, the next time it blew off it went into the field next door. I then put it on with even more screws and reinforcement, it did not blow off again. But it can get windy here and I have watched from inside the conservatory as lots of large rain drops come straight at me before hitting the glass, it was very unnerving.

I have also had a horse field shelter flat packed by the wind, that had an onduline roof nailed to joists and the complete roof was almost intact afterwards.