The downstairs toilet on our house was originally part of the garage. It has the original asbestos roof which appears to be simply ply lined on the inside. Door cut through into the main house and blocked off from the garage now. I believe the walls do have a cavity

It is very cold. The ceiling is low, but there is some space – I’m wondering about fitting some sort of solid insulation – is something like kingspan okay for a bathroom of this construction? I’m not expected to make it as good as the main house but would like to improve.

Any other suggestions or ideas? Replacement roof is on the 5 year plan subject to interest rates

This thread sounds very similar
http://singletrackworld.com/forum/topic/buildingtrackworld-how-should-i-insulate-my-bathroom-roof

I have 2 sloping ‘rafters’ down to just over 6ft. I can’t tell the ventilation above the ply lining but imagine it to be ‘lots’ given the temperature and the rest of the house.

So simply overboard? Should I expect much improvement in keeping the room warm?

Is there a radiator in there? I’d get a plumber to pipe one in if not.

So simply overboard? Should I expect much improvement in keeping the room warm?

When we moved into our place, the uninsulated, built onto the back, bathroom was shiveringly cold even with the heating on full whack, it was just boarded under the tiles. Solid insulation between the roof and the ceiling made a huge difference. So yes, I’d say it would potentially help, though I guess it depends where else you’re losing heat. But yes, a big difference for us.

I was pondering this exact question this morning as i realized our utility room that has a poly-carbonate roof was rather brass monkeys.

I was wondering about the kingspan stuff until i looked at the price. I’m contemplating whether to throw some rockwool up there and pin it back with some battons. This way i can still remove it in summer once it gets warm as it does let in a lot of light.

Either that, or i propperly re-roof it with a properly insulated and slated roof

Kingspan style PUR foam is twice as effective per thickness as glass fibre, which makes it an excellent material where space is tight.

“call yourself an extension! your nothing more than an outbuilding, a shed at best!”

Damn it, trailwagger beat me to it.

Interesting:

Kingspan style PUR foam is twice as effective per thickness as glass fibre

How important is it to get a tight fit around the outside to stop air leakage? For example if i cut it to fit and wedged it in but left a 20mm gap at one end, would this ruin the insulation gains?

My roof is far from straight (like the rest of the house) so though rockwool would be easier to get to the edges than trying to cut lots of random bits of solid foam to fill the gaps

Draft exclusion is pretty important, otherwise your warm air disappears around the edges.

That’s where glass fibre is useful

Yes already a radiator in there. I have around 12cm from the current ply line to the depth of the two sloping rafters. Would have to come up with some sort of taper where the window is as its up to the roof line.

Can you cut down lighters into king span?

I’m going to setup another thread on draughts

Yes you can put lights through solid insulation as long as there’s a suitable facing material underneath to attach them to.

Researching a bit more, thinking about insulating the walls with insulated plasterboard. In order to save some pace would it be worth taking all the plaster off before fixing? Probably save 10mm or so, given its a small room this would make a difference

You won’t need it for the cosmetic finish, and 10 mm extra insulation will be significant at the smaller thicknesses you’re talking about.

I would. Once you have a working edge the plaster should come off nicely.

If you only have 12cm space then I’d look at insulation board as the recommended depth of mineral is 270mm, last time I looked anyway.

Insulated plasterboard is great stuff to use if you’re right for space. You can also fix it using adhesive (from a gun or the expanding foam type) if you got something decent behind too which saves on stud/dot and dab thickness. Just make sure the adhesive is compatible with the foam first!

What type of adhesive? No more nails type stuff? I’ll have a brick wall to fix it to, but currently very uneven as some bricks have crumbled