I’ve got an attached garage that I want to turn into a man cave for my bikes. It was built in the late 60s, flat roof, single skin. I was planning to insulate the walls with Celotex or equivalent and line with plywood. Do I need to use plasterboard instead for building regs? Plywood would be preferable for screwing things to.

Is it worth using Celotex for the roof? I’m going to insulate from underneath (I believe that insulating a flat roof should ideally be done from the outside but I don’t fancy ripping up a working flat roof).

The door will be lined with Celotex and I’ll draft proof it as best I can. I suspect that’ll still give me a reasonable flow of air to deal with any damp.

Any suggestions for the floor? Plywood seemed a good choice there too.

Plywood sounds expensive. Some of that cheap 2*3 stuff from B&Q for stud like walls, loft insulation in the gaps, chipboard, lining paper.

Freezing in the summer, toasty in the winter. Fine for screwing things in to.

OSB also know as sterling board. Cheap and quite strong.

2nd sterling board too as ply is cash monies! I’d be tempted to only do the sterling board in a band at the height you will be screwing stuff too.

For the floor I got myself some concrete, levelled the damn thing out (which was a right bugger in a 30s garage), then I came up with my own little recipe: I bought a load of PVA, covered the floor in that waited for a couple of days for that to dry up. Laid down some 10mm insulation wool, which was duly covered in OSB (from B&Q of course 😉 ) I then used up the remainder of some opaque rubbery floor tiles (which were heavily over-bought when doing up our patio) and they cover the garage nicely… It’s bloody nice with some storage heaters in winter, never had problems with damp in the last 18 months since I’ve had it and jolly nice to walk on in slippers 😀

My perfect man-cave!

So wish I could have a den. 🙁 got an 8 by 10 shed but too much crap in it to give you any space to sit in. Once the little un out grows her little playhouse alongside I may have to make an extension, could have a porch then and a rocking chair on it 😀

OSB looks like the stuff then. Thanks for the tip.

You planning on painting all this sterling board? I think you should be lining it in gyproc, filling, painting on top of the boards. It will give it an extra half hour fire protection to.

Do I need to use plasterboard instead for building regs?

Probably the last thing I’d be considering are ‘building’ regs…

I added a door draught protector to the bottom of my lift-up door, helped big-time.

Whatever you screw your stuff too, make sure you make an awesome shadow board for your tools.

I’d go with 9.5mm plasterboard on CLS (65x40mm?)studwork would be very cheap, strong enough and plenty warm enough. You could insulate the ciling with bubblewrap.