Insulation in cavity walls - new build

looksee

I've been doing some reading on different types of building, I thought that timber frame units were the way to go but am coming back round to cavity block walls.

I am getting the impression that cellulose is the best insulator in the long term, and in new build cavity walls it is usually blown in. What I cannot figure is how this works.

I had the impression that there should be a moisture gap between the outer leaf of the block wall and the insulation in order to allow for moisture to dissipate. However the insulation, and certainly the cellulose, seems to be applied directly to the outer block leaf. How does this work in terms of moisture going through the blocks? And if the two sides of the cavity are built then the cellulose blown in, how can you be sure it has actually filled the cavity? I can only find diagrams of timber frame being sprayed on, and that seems to happen before the inner leaf of plasterboard etc is applied.

Can anyone direct me to any vids or sites that discuss this issue, or explain the process for me? Thanks

BryanF

looksee wrote: »

certainly the cellulose, seems to be applied directly to the outer block leaf. .

It’s not.

looksee

BryanF wrote: »

It’s not.

Oh right, how is it applied?

BryanF

looksee wrote: »

Oh right, how is it applied?

Plasterboard, service cavity, vapour barrier, timber frame with Cellouse infill, smart ply with gaps siliconed, breathable membrane, ventilation cavity, block or cement board or cedar, or whatever takes your fancy

looksee

BryanF wrote: »

Plasterboard, service cavity, vapour barrier, timber frame with Cellouse infill, smart ply with gaps siliconed, breathable membrane, ventilation cavity, block or cement board or cedar, or whatever takes your fancy

That all applies to timber frame housing though? I am trying to figure out how/if cellulose can be used with cavity block. Or are you saying it can only be used with a block outer skin rather than cavity block building?

Edit: Ah yes, finally found a reference to cellulose in new build double leaf walls and the answer appears to be no, it does indeed create a moisture issue.

Thanks for your help.

mp31

looksee wrote: »

Edit: Ah yes, finally found a reference to cellulose in new build double leaf walls and the answer appears to be no, it does indeed create a moisture issue.

Could you PM me that info please if you don't mind?

looksee

mp31 wrote: »

Could you PM me that info please if you don't mind?

Sorry, I looked for the quote, and it didn't say any more than that, but I couldn't find it again.