Dry Lining Exterior Walls

[paulatwizzer]

I have just bought a property made from solid concrete. The exterior walls are battened and covered with a single layer of plasterboard. I wish to remove this plasterboard and insulate the wall with slab rockwall between the battens and then apply a new surface of foil backed plasterboard would this be correct? I am sure that a vapour barrier should be in there somewhere

 

[masona]

I wish to remove this plasterboard and insulate the wall with slab rockwall between the battens and then apply a new surface of foil backed plasterboard would this be correct? I am sure that a vapour barrier should be in there somewhere

Yes,that's okay. The silver backing on back of plasterboard is to reflex heat loss back into the room and also moisture or damp from the other side.

 

[GwaiLo]

I would strongly advise that you get some advice from a chartered building surveyor before doing this. Applying insulation internally on a solid concrete wall may well lead to interstitial condensation and of that were to occur within the insulation it would soon become innefective and you could get damp internal walls.

Alternatively you could do some research yourself (I am not going to go so far as to provide calculations here) and calculate where the dew point will be at a range of internal and external temparatures.

 

[silverlink]

My house (Victorian) has solid brick walls. I recently insulated the utility room by battening the walls with treated battens then infilling with 25mm polystyrene slabs. I then stapled heavy polythene sheet over the lot before plasterboarding and skimming. I figured this would prevent moisture ingress and so far have had no problems. The room is 10 times warmer and no condensation running down the walls.

 

[GwaiLo]

Solid concrete walls and solid brick walls are not the same thing at all and the risks of doing what you propose to a concrete wall are serious.

Condensation occurs at the point where the air temperature is reduced to the dew point of the internal air. Often that happens on the internal surface of the wall where you can see it. By insulating a wall internally you move the dew point outwards. In a solid masonry wall that isn't really a problem, but in either a cavity wall or a concrete wall you may move they dew point to a position where condensation occurs within the wall where you cannot see it (and therefore you assume everything is fine and dandy), however if that point coincides with the position of the steel reinforcement (or steel wall ties in a cavity wall) then the consequences could be catastprophic. The steel could corrode, the wall could lose its structural integrity and you may know nothing about it until one windy night when you wall falls down taking everything it supports with it.

It is always, and I do mean always (even with solid brick walls) best to insulate on the outside. There are insulating render systems and the like that can do it, although insulating internally is a great deal cheaper and therefore quite commonly done. But do it to concrete walls or cavity walls without professional advice or at your peril.

 

[masona]

There are insulating render systems

They are doing this down the bottom of my road and can't quite see how they're doing it.Not sure if this is what you're talking about,they put up a insulation slab on the outside walls about 50mm thick (is it foam ?) not sure how they are fixing it,then they renderer over with sand/cement,finish off with pebble dash.Does anyone know or heard of it or more details?

 

[GwaiLo]

I have specified similar systems in the past masona and they are widely used in the refurbishment of social housing. It is very effective, but not cheap. It does have the added benefit of improving the appearance of concrete panel walls too.