Cavity Insulation insallation during bricking up old doorway

[daz3770]

Hi there all,

I am bricking/blocking up an old doorway in an external wall, as part of renovation works.

The building is about 80 years old and the cavity is max 45mm.

My question is, what is the best form of cavity insulation to use, while making sure that moisture is not transmitted through?

Kind regards.

 

[PrenticeBoyofDerry]

Celotex/Kingspan or something of that ilk.

 

[daz3770]

I think i read some where that moisture can penitrate Celotex. Is that misleading info?

 

[PrenticeBoyofDerry]

if the joins are sealed the foil will prevent moisture.

 

[freddiemercurystwin]

A rigid insulation such as Kingspan or Celotex is unsuitable for such a small cavity. A full fill insulation with a water repellent designed for the job would be better something like Knauf Dritherm cavity slab, think you can get that in 50mm so that would be ok.

 

[daz3770]

Thanks for the help gents.

I will head out for the supplies.