Internal cladding advice

[Ronob]

Part of my house is of solid brick construction the small sitting room gets very cold in winter so I’m thinking of insulating the outside walls with some kind of foam or polystyrene type product then plasterboard over.
I need to keep the thickness of the insulation as thin as possible to avoid taking too much off the size of the room, so my question really is what would be the most thermally effective material to line the wall with?

 

[mikeey84]

If money is no object, aerogel is the most effective. However, this comes with a significant cost. Lots of people report 50mm celotex has a significant impact, but the law of diminishing returns applies, so even 25mm of celotex is going to have a big impact

 

[^woody^]

Rather than thinking "what's the thinnest I can get away with", think instead " what's the maximum I am prepared to lose off the room".

 

[Ronob]

I’m hoping to get away with just 25mm with 9.5 plasterboard tops. I know I can get 35mm insulating plasterboard. I’m wondering if there is a foam/polystyrene or other insulation material that performs better.

 

[mikeey84]

As above, the more you pay, the better you get.

25mm celotex will make a difference, but aerogel will be much more effective but 5x the cost

 

[^woody^]

Is aerogel UK certified - BBA etc?

The website looks like it was designed for Myspace 15 years ago and has a lot of techno-documents which indicates that they are trying to prove something by blinding with a load of scientific waffle, but are really not saying a lot about performance in use.

None of the similar thin "miracle" insulation quilts actually perform as claimed.

 

[mikeey84]

Is aerogel UK certified - BBA etc?

I'm no expert, but I think so? Top link when Googled was what looks like a bba certificate, but I don't really know what one would look like.

It has the thermal performance details in there.

 

[^woody^]

Not that good then.

 

[mikeey84]

No, I was surprised, as I was under the impression it performs much better than that and other published info claims much better performance.

I'll stop recommending it now!

 

[JohnD]

you can knock off the original plaster, it may save a bit.