Okay to use lightweight thermalite blocks for bricking up a window (cavity wall)

[trancenotes1776]

Good day firends, Is it okay to use those grey, lightweight Thermalite Aircrete blocks for br icking up a window in a cavity wall? The outside of the wall will be render ed with sand & portland cement afterwards. As it's just a window I want to brick up, it will not be load bearing. I'm mainly concerned about the moist ure absorbtion tenedencies of these blocks. (They soak up damp like a spong e, don't they? I'm not sure if that's an issue or not. Does rendering stick to them okay?)

Many thanks,

JD

[The Natural Philosopher]

Justs fine mate. I've seen whole houses made of em.

Put a vapour barrier inside tho

[trancenotes1776]

On Tuesday, August 16, 2016 at 12:35:19 PM UTC+1, The Natural Philosopher w rote:

r bricking up a window in a cavity wall? The outside of the wall will be re ndered with sand & portland cement afterwards. As it's just a window I want to brick up, it will not be load bearing. I'm mainly concerned about the m oisture absorbtion tenedencies of these blocks. (They soak up damp like a s ponge, don't they? I'm not sure if that's an issue or not. Does rendering s tick to them okay?)

Thank you! When you say 'vapour barrier', do you meaning something like she et foam polystyrene inside the cavity? The existing walls have 30mm sheet p olystyrene inside the cavity. If I emulate this when I brick up the window with thermalite blocks, will this serve okay?

JD

JD

[rick]

I would not use Thermalite on external skin ... if that is what you are intending doing ........... using plain concrete (cheaper as well) Use Themalite on inner skin. Don't forget dpc integrity - don't bridge the cavity.

[Andrew]

It's fine. He's going to render it. I've seen numerous extensions done this way, even with a solid 9 inch wall constructed of grey semi-lightwweight blocks, rendered and coated with pea shingle for weather protection.