Howdy all

We had cavity wall insulation installed 3 or 4 years ago -- the blown
fibre type.

Investigating a "dampish" smell in the house yesterday (I haven't found
anything yet!) I went under the floorboards to check that the airbricks
aren't blocked from the inside.

One was actually blocked with the remains of a wasps' nest, but all the
others (only 6 in total, semi-detached house) are free ..... except that
there are signs of the CWI around the perimeter of the air bricks. It
occurred to me that maybe I ought to install some kind of frame around
each brick in order to prevent this happening. Would that be overkill?
Or to put it another way, what's the chances of CWI moving, and blocking
air bricks?


Secondly, I noticed that some of the CWI has in parts gone down below
the damp proof course: any harm in that?

Cheers
John

On Dec 8, 7:28*pm, Another John wrote:
Howdy all

We had cavity wall insulation installed 3 or 4 years ago -- the blown
fibre type.

Investigating a "dampish" smell in the house yesterday (I haven't found
anything yet!) I went under the floorboards to check that the airbricks
aren't blocked from the inside.

One was actually blocked with the remains of a wasps' nest, but all the
others (only 6 in total, semi-detached house) are free ..... except that
there are signs of the CWI around the perimeter of the air bricks. *It
occurred to me that maybe I *ought to install some kind of frame around
each brick in order to prevent this happening. *Would that be overkill?
Or to put it another way, what's the chances of CWI moving, and blocking
air bricks?

Secondly, I noticed that some of the CWI has in parts gone down below
the damp proof course: any harm in that?

Cheers
John


The blown fibres are treated to make them water repellent. Bridging
of the damp course won't let moisture get past it.
Your problem is unlikely to be related to the cavity wall fill.
It could be related to a condensation problem. Best remedied at source.