Where to get 5'x5' OSB?

[paintguy]

Hi,

A few years ago I bought a cheap 8x10 shed. False economy - never again!

Anyway, due to thin leaky felt on one side and the crazy sun we've had lately the roofing sheets have sagged really badly. They're made out of thin OSB so aren't up to much anyway. I'd like to replace them but there are four sheets, 5' x 5', and I can't seem to find anything bigger than the regular 4' wide sheets. Any ideas?

Plus, is OSB the way to go? Or should I be looking at WBP ply or similar? I'll be going for something a bit thicker than what I have now, probably 12mm at least.

I also have a load of 25mm Kingspan going spare so the idea was to re-sheet the roof, put a layer of kingspan over it and then felt over, using some timber batons between the insulating sheets for nailing it to.

 

[paintguy]

Thanks for that. I work almost exclusively with MDF for my DIY projects so I'm not too up on other types of sheet.

I ended up building new roof frame with 2x2 & using 8x4 sheets of 18mm osb3.

Ha, I'd been thinking about exactly the same thing when I couldn't find sheets 5' wide. This thread was kind of my last resort before going down that route! Good to know it works.

Raising the roof slightly on a new frame would also allow me to put the insulation on the inside, making fixing the felt easier as it could go direct to the OSB.

 

[paintguy]

Why bother with the insulation if it's unheated total waste of time

I'd be using it more to try and reduce the temps in the summer really. It's leaky as hell so as you say there's no point using insulation to try and keep the heat in. Reflecting some of the suns heat would be a bonus though. Plus I hate to see it wasted as it'll only get thrown in a skip if I don't use it

 

[paintguy]

Hmm.. Maybe I need a rethink on that one then.

The roof (all 100s*** of it) gets so hot it heats up the inside like a huge radiator. I'd thought by insulating it I'd reduce that effect. Plus being foil faced it should give some kind of radiant barrier effect too.

I've even thought about putting a vent in the wall opposite the door, high up in the apex of the roof, to try and get a bit of chimney effect going on.

EDIT: why is an abbreviation of square feet starred out by the swear filter?

 

[paintguy]

Only for my own comfort. It's more of a workshop than a shed with a router table and other goodies built into it so I often spend hours at a time in there.

I also do a fair bit of fiberglass construction in it. Even when under-catalysed the laminating resin goes off way too quickly when it's 30°C or more inside.

 

[paintguy]

"glass" is all fully covered with that green radon barrier plastic to keep prying eyes out and reduce solar gain as much as I can.

When its really hot I have a 20" box fan blowing in through the door in an effort to push the hot air out. That's why I was thinking about a vent high up on the opposite wall. A couple of vents in the roof is a good idea though. Maybe high up in the ridge.

Or thinking on my feet here, maybe fit the box fan on the opposite wall like an extractor as you suggest. It'll help to pull the fiberglass & paint fumes out too! I can easily make a rain proof shutter for it.

Power isn't a problem. It's the only shed for miles with a 32A ring main

 

[paintguy]

^^ Sounds pretty much like mine, although thankfully there's not a spot of rot in sight. All the gaps in the seriously warped overlap panel walls give it plenty of ventilation!

A good solid base has really helped though. I couldn't get a mixer in so didn't go for a full concrete base, but did a perimeter of up-ended paving slabs set in plenty of hand mixed concrete. Lots of well tamped down hardcore, a layer of sharp sand and heavy duty paving slabs on top. The shed base is lifted off this on some treated 3x3 timber fence posts to allow plenty of ventilation underneath.

But I'd never buy a cheap shed again. Even though it's still going strong after 5 years apart from the roof, I'd go for a T&G / Shiplap one if I ever need another (I've already got two!)