Fitting Celotex to alcoves

[RJH]

I'd like to lose as little space as possible, so I'm proposing to rebate some battens into the existing plaster, and fix 25mm Celotex and 9mm plasterboard to the battens. Is that about right?

[The Natural Philosopher]

is this an outside wall then?

[Jim K]

Just glue it on & forget battening?

Jim K

[Tim Watts]

On Wednesday 17 July 2013 18:22 RJH wrote in uk.d-i-y:

25mm will make a massive difference over nothing. More the better, but when space is a consideration, even 25mm will be worth the effort.

[RJH]

Yes.

[RJH]

Mmmm. Tempting! However, the Celotex is foil coated both sides - so it would effectively be held on by the foil. I think a screw needs to go through the plasterboard and the Celotex.

[RJH]

Hopefully. It's more a stab at comfort than saving money. The room (ground floor 3.5mx3m, 9" solid brick to two external walls, suspended timber floor) seems to wick heat with some style.

[The Natural Philosopher]

id say use the plasterboard/celotex composite and simply glue it on.

no need for more than 6mm board and as much celotex as you can fit in.

[Dave Liquorice]

+1 Did the end wall of the lads room with 25 mm celotext bonded to plasterboard, only two sheets but a very noticable difference to the room afterwards. It was an outside wall, 12" or so random stone.

I'm another having trouble relating "alcove" with an outside wall. Little point in insulating internal walls as any heat "loss" through the wall is still inside the building.

[The Natural Philosopher]

been there had one of them.

Hint. Biggest gain was lining floor with hardboard tacked down and taped over the cracks, then carpeted

[Jim K]

er 6mm of what? & made by whom?

Jim K

[Jim K]

a) you can buy sheets of "ready assembled" pb glued to "paper-faced foil" insulation. b) "proper" installation (IIRC see British Gypsum website) calls for 2 long frame fixings through each sheet 1/4 way down to hold it up in case of dire circumstances....

Cheers Jim K

[Tim Watts]

On Wednesday 17 July 2013 20:20 RJH wrote in uk.d-i-y:

Putting 15-20mm of closed cell polysterene foam on the floor (actually marmos, saoid foam has both faces bonded to cemented glass fiber mat) under the wood and bathroom tiles made a ginormous difference to the comfort in winter. Hall floor (no marmox) sucks the heat out through your feet, but the bathroom floor, whilst not warmed, is perfectly comfortable.

One thing the 25mm of celotex will do is cut down on cold air convection running off those walls.

[RJH]

Here's hoping. It's a relatively cheap and easy ( I'm another having trouble relating "alcove" with an outside wall.

By alcove I mean an external wall each side of a chimney breast.

[RJH]

On the floor is less of an option. I have a bundle of fibreglass I was going to net/tack between the joists, and pay some attention to draught routes. In addition, thick underlay and carpet.

[RJH]

Long story, but I have 10 sheets of 25mm Celotex and 9mm plasterboard.

Aye, good point - I'll take a look at their guidance.

[The Natural Philosopher]

I was puzzled, but I remembered those old cottages with chimneys on an outside wall, and an alcove either side.

[The Natural Philosopher]

Muy bad, its actually 9mm plasterboard and a bit of celotex. That's the thinnest celotex composite

they say its fine to dot and dab it.

So that's what I would in fact do.

Sharp knife a bit of glue and its up in an hour or so. Then skim it and caulk the corners, or paper it. Nice expensive paper can look great in an alcove.

[Jim K]

Probly 9,5mm in reality.

Jim K

[Dave Liquorice]

Ah...! Similar to here, all our fireplaces are in gable end walls but the walls are thick enough to have everything within the thickness of the wall, no alcoves...