My house is solid walled house about 100 years old. The back of the house floor below the window is about 2ft below ground and this wall on and off suffers from condensation, its has a bitumous barrier behind the plaster. I wondered about sealing some tri iso super 10 behind plaster board, or plaster backed celotex and attaching (screw of nail?) to the walls, is this a good idea or do I need an air gap as well, what would people recommend? Thanks
A rigid insulation board is ideal for this. Stick it to the wall, tape up and joins with foil tape to create a vapour barrier, and then fix your plasterboard through it (you can either fix directly to the wall, or fix battens to the wall first and fix the PB to these. Note the latter approach will reduce the insulation effectiveness a little. Basically you just need to stop the warm moist air from hitting a cold surface.
If fixing direct to the wall, then screws and plugs. If using battens, then dry lining screws.
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Thanks, so basically foil backed celotex with foil on room side. Glue to wall. Seal joins etc. Plasterboard on top screwed through to wall. I was only going to do the bit below the window and so top will need finishing Just more plasterboard? Note some of the back wall is internal. Also does it just sit on the floor boards or do the need to be removed so it sits on the joists
Much of it comes foil on both sides - but not a problem.
Last time I did something like this was in a large cupboard. This was basically a 4' slice that had been taken off a room to create a staircase - so it was very deep. At the far end there was a section of outside wall under a half landing. Since this was solid brick and there was no ventilation it attracted lots of condensation. That ran down the wall and rotted the floor etc in the area. The whole underside of the floor was soaking, and the joists in the area had had it as well.
So I stuck a sheet of celotex to it with expanding foam. (not even got round to adding the PB yet since its in a cupboard anyway). That stopped the condensation nicely. Replaced the rotten wood with treated stuff, and added extra air bricks t make sure there was a nice draft under there to keep it all dry!
PB or wood if you want something a bit more resilient to knocks - especially on the corner. You could perhaps make a feature of it with a dado shelf or rail or something.
Depends on how much of a pain it will be - which way the joists run etc ;-) also check the state of the timbers at the base of the wall as well.
Ideally take the insulation down to at least level with the underside of the floor. Make sure there is adequate under floor ventilation as well. However is difficult to get the insulation right down, then stop adjacent to the floor and seal the floor to wall gap with mastic to stop damp air penetrating the gap and condensing onto the end of the floor.
I wouldn't attempt to drill the walls at all. The concrete is not very strong or thick on most of them.
I would make some angles out of builders band and fix it to battens and then to the bolts holding the panels together. it will give space to put some fibre bats behind for insulation.
Opps, wrong thread, please ignore.
Thanks, sounds relatively easy
Yup, or you could start with celotex backed PB, or for that matter glue the PB on etc.
Won't hurt to insulate over that bit as well if it looks more consistent.
If you take it down to the floor, then seal it with a line of mastic at the bottom to prevent moist air getting into the gap and condensing there. Make sure there is adequate underfloor ventilation as well.
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