Insulating a wall

[the-shack]

Hi,

I have a double brick wall without a cavity that I need to insulate.

To achieve the required U value I'm going to be fitting 50mm Celotex directly to the wall and then fitting 25 x 50 battens 600mm apart screwed through to the wall. The joints will be taped and the edges sealed with mastic to provide a vapor barrier. According to Celotex's information this will give me a U value of 0.35W/m2K.

My question is should I use tanalised timber or kiln dried? I currently have tanalised but it has been delivered wet and I don't think I can use it.

Help please as this is now holding up my build.

Thanks

 

[^woody^]

Treated timber is preferred. It will dry off.

In fact, the design should allow for moisture to evaporate out of any void

 

[the-shack]

Thanks woody

I've got the timber inside now so hopfully it will have dried a little before I use it.

I have had it suggested to fill the 25mm gap with jablite. Given what you have said I assume that I would be better to leave this as an air gap to allow it to breath.

Thanks again.

 

[^woody^]

It's often better to have no air voids at all, as this reduces the chances of interstitial condensation - ie condensation forming inside the wall