"fred" wrote in message
...
On Thursday, August 25, 2016 at 9:05:37 PM UTC+1, KYW wrote:
"Jeff Layman" wrote in message
...
I'm putting together a woodstore, but am wondering what to use for the
roof, I've been considering ply, but even the exterior stuff will need
felt, it seems. Or would Flexacryl or several coats of exterior varnish
be
sufficient?

I had a look at corrugated PVC, but it seems a lot thinner and flimsier
than I remember from use many years ago. Polycarbonate twinwall is
overkill and on the expensive side for this type of use.

Basically It doesn't have to last 20 years, but I'd like it to last at
least 10 before any repairs are needed.

Any other ideas for roofing?

Metal decking. Cost **** all for that size roof, lasts much longer than
40 years, need no structure at all, just a coupla bits of timber. Dont
need any real slope at all, just vary the depth of the timber is fine.

What I call corrugated iron, (i.e.) Corrugated galvanised
metal sheet is the cheapest and strongest alternative.

Yes, it is certainly cheaper, but nowhere near as strong as it is lighter
gauge
metal. And metal decking has no fasteners though the decking, it has clip
that are fastened to the rafters, the decking goes on those and is crimped
after that so there are no holes thought the decking at all. And works fine
at a much lower slope than corrugated galvanised metal sheet too so is
much cheaper structure wise for a small roof like that.

I once heard a structural engineer propound the the corrugated iron in the
old round roofed shape hay barns, was the strongest part of the structure.
And wern't some of the Nissen/ Quonset round roof huts made with
corrugated steel sheets ?

Yes, but a small woodstore roof isnt practical like that