8" walls on extention

[blake floyds]

I am building a single story extention on my bunglow and my mate has said he has loads of blocks to do it but they are 8" blocks
can i use these and put insulation on the inside or do i have to have a cavertiy

 

[^woody^]

You don't need a cavity.

But you will need to ensure that moisture won't pass through to the inside face

 

[blake floyds]

thanks
how would i do that with a membrain or some sort of paint

 

[Richard C]

Assuming it’s a habitable extension, if I were going to all the trouble to build one (& I have) I wouldn’t bother using a bunch of solid blocks just because they happened to be ‘available’. I think it’s a false economy that will involve you in additional expense & agro in other areas in order to comply with BR’s! Build it with a proper insulated cavity; bricks/blocks aren’t that expensive, it’s the labour that pushes the price up!

 

[^woody^]

Painted render and continuous internal insulation lining should be enough for all but severe exposure locations, but the BCO may want a vertical [polyphene] membrane or breather membrane on the inside face before the insulation or before the plasterboard

Richard

I don't think it will be a false economy, and it will be just as good an end prodcut as cavity construction. The only issue if anything, will be the regular repainting of the render, as opposed to an external brick skin possiblw with a cavity wall.

If the OP gets the blocks cheap or free, then thats a major cost saving. But if they are dense concrete blocks then laying costs could be very high, as no-one likes laying these nowadays.

 

[blake floyds]

Thanks a lot for your comments

The blocks are free and I was going to render any way so it looks like I will use them