Topping up cavity wall insulation

Mar 26, 2014 13 Replies

We have blown fibreglass insulation in the older parts of the walls.



During the extension work we must have lost some of the original cavity wall insulation.



Is it possible to top up this kind of insulation?



Given that the normal method of installation is blowing up from the ground floor could this be done for a top up?



Cheers



Dave R


You won't miss it..

you can't install it by blowing it up from the ground floor, you have to have holes quite close together to get anywhere near a proper fill.

Why do you think that?

Yes. Polystyrene bead is easy to diy - if its actually needed.

NT

I've had windows replaced and two wall cut-outs made in a house with CWI, and it was obvious that some was lost: fluffy stuff blowing around the garden...

Umm...I saw it coming out and blowing around.

Just not sure how much we lost.

Polystyrene bead can be done with just a handheld hoover and a waste pipe. And something to make the holes. Do holes frmo the inside, daft to damage the bricks for the sake of a bit of filler.

NT

If you drill it in the mortar joints you don't damage the bricks.

cant get big enough holes without cutting brick corners off.

NT

Are you recommending beads to top up a fibre fill?

I simply said its an option.

NT

They seem to manage on most houses, do you have a thin joint system?

Doing beads properly is difficult without the correct equipment, they are supposed to be coated in glue as they are blown in.

If they aren't they fall out through even small holes.

On most I've seen you can see the brick damage where they've blown it in

NT

Glue coating is less easy to diy without the right kit. But for walls that are generally not recommended to be CWIed you need the beads uncoated so th ey can be sucked out if ever needed. Yes, it does mean checking for holes : ) Otherwise christmas comes early.

NT

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