Greetings,

Long time, no post! That's the problem with actually having a job- stops me getting anything fun done!



I'm custom building my own shed. I'm trying to build it both as securely and aesthetically pleasingly as possible.

However, the back panel of it will be largely hidden by dint of the shed being up against a fence. Therefore, rather than being clad in shiplap like the other 3 sides I was thinking something else.

Rather than shiplap or feather edging I had ideas of using sheets of OSB that I then covered using roofing felt. This would protect the OSB from weather etc.

However someone's told me that OSB is waterproof so could be used uncovered. Therefore saving buying a sheet of pricey roofing felt.

Can you use OSB externally? What about if painted/treated?

What else could I use instead of the OSB? It needs to be waterproof, secure and cheap.



Thanks,
James

You can get exterior osb but it will still swell eventually.It's not that cheap either especially when you factor in the felt. I would go with exterior ply with a coat of treatment or varnish.

I built my shed against a brick wall. I used cheap plywood covered in green mineral felt. This turned out to be more durable than the shiplap timbers, most of which have been replaced. It has been up about 12 years now.

Not waterproof in terms of long term exposure. Id call it resistant, same as marine ply.

only the glue is waterproof. Well, that's what the bloke in the timber merchants said.

quote:

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Originally posted by JoelP
Not waterproof in terms of long term exposure. Id call it resistant, same as marine ply.

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its waterproof if it doesnt leak ?

no wood is water resistant and especially osb... , id even use brazillian ply over osb if you cant get marine ply .

grp on the other hand is waterproof from the get go ...

NO ! NO ! NEVER Use Oriented Strand Board for Anything.
Garbage is the best/only descriptor. I say that, despite that a friend of mine 'invented' the crap... true.
There are now laws restricting it's use.. in it's birthplace: BC Canada.
The glued together wood shavings absorb moisture from the atmosphere.. even indoors and subsequently swells, usually dramatically, in thickness. This does bad things to fits and any overlayments.
When used in semi exterior situations ie; sheathings under siding/ stucco the crap Really swells, then starts to Rot.. causing genuine grief.. but even worse; promoting Mold growth.
Astoundingly the US market house builders perceiving this as a cheaper alternate to plywood (which has None of the above faults) have demand bid the price up beyond that of plywood.
No one can make this stuff up.. it's just too stupid.

My half OSB shed has been up over ten years now, I painted it with some sort of waterproofer when I built it and it has been OK.



I have had to replace the roofing felt a couple of times and the door (also OSB) is getting a bit scabby now.

HTH

Neil

I built mine with Marine ply over both sides of a frame to make a double skin wall, and then clad the outside with shiplap to make it look less secure and curious. Its been up 5 years now, and no problems at all, though the hawthorn bushes are starting to invade slightly.