Cladding a workshop - Expansion gaps?

[LancsRick]

I'm in the process of moving home, so my planning brain is going in to overdrive. Top of the list (of course!) is how to change the single skin detached double garage into a great workshop. I've asked questions on the general approach in a different thread, but now my queries are quite specific.

The walls and floor will have a treated timber frame with insulation fitted, and DPM on top. The walls are then going to have OSB cladding, and the floors T&G chipboard (22mm). Now, this is where the internet seems to have as many opinions as there are pages...

For the chipboard floor and the OSB wall cladding, do I need expansion gaps or not?

I'm in the northwest, so mostly cool, and the workshop will have an oil radiator and dehumidifier to keep a decent level of control in there. At a guess I'd say the variation would be no lower than 5C and no higher than 20C in a year.

Thanks for any and all inputs!

 

[MikeG.]

Can you please be a bit more specific about the build up of the walls, working, from the inside to the outside, and include the existing building walls. I'm particularly interested in the location of the DPM and the OSB.

 

[LancsRick]

Current wall is single skin brick. Proposed wall will be (inside) osb - dpm - treated timber with insulation - brick.

 

[MikeG.]

Will the timber inner skin be spaced away from the brick?

 

[LancsRick]

No, treated timber flush to brick.

 

[MikeG.]

OK, well in a workshop that's not the end of the world. It wouldn't be acceptable in a house. You can omit the VCL (vapour barrier), but you must make sure you don't leave any voids in the build-up. In other words, best to use mineral wool insulation than Celotex unless you can be sure of getting the latter completely flat to the inside face of the brickwork. If you do use Celotex then have a foam gun ready to squirt any gaps. As for your original question, you should leave a couple of mm between the sheets of OSB. I use a couple of nails as spacers when doing this. 9mm OSB is fine.

The floating floor should have a 6 to 10mm gap all round the edges, covered by the skirting which traps the edges of the boards down.

 

[Beau]

My chipboard floor shrinks back a bit in the summer. Would estimate a 1mm gap between the sheets in the driest weather. And tight as a tight thing the rest of the time. Only time I have used OSB on walls was in our house behind the plasterboard. I have observed stuff all movement on these.

Take Mikes advise and get a foam gun to fill any gaps between the Celotex. So much easier than the cans with a nozzle.