Forum Topic

Cavity wall insulation recommendations

Has anybody had cavity wall insulation installed recently by an installer whom they can recommend?Thanks in advance.

Peter John ● 1382d12 Comments

My recommendation is "don't". Or at least, proceed with very great caution.Traditional double skinned walls are designed to keep the damp external skin separate from the dry internal skin, with a ventilated gap in-between, so that moisture runs down the inside face of the external wall.I have heard that it can work.  But I have heard far more stories of it not working and causing damp problems.  But then like so much in life, perhaps we only hear when thing go wrong.

T P Howell ● 1381d

There was a recent report that roughly 25% of CWI installations had problems but unfortunately did not really break down what the problems were, see:https://www.thisismoney.co.uk/money/news/article-10390579/Botched-cavity-wall-insulation-ruining-homes-causing-damp-mould.htmlGood news is that a home in London is not really exposed to salt laden sea winds (I would not recommend CWI on coastal properties unless sheltered).  As long as the installer first does a proper survey and crucially sticking a camera into the cavity to assess whether there is any significant builder rubble in the cavity (which would cause cold bridging and eventually damp problems)

Justin Stephenson ● 1381d

Most of the houses in Chiswick don't have cavity walls. They are solid 9 inch brickwork

david ward ● 1379d

https://www.which.co.uk/reviews/insulation/article/cavity-wall-insulation/cavity-wall-insulation-installation-arnH44k0K4gA#is-your-home-suitable-for-cavity-wall-insulation

Philippa Bond ● 1378d

Think twice,your house has 2 seperated walls for a good reason.

Keith Iddon ● 1378d

Another website for you to look at.https://energysavingtrust.org.uk/You just need to, as you are trying to, progress with care.

Philippa Bond ● 1375d

what age is the house?

david ward ● 1373d

It depends on the quality of your brickwork and the quality of your damp proof course.  If either is suspect DONT!Anything built before ww2 is likely to have porous brickwork, and that plus ventilation below floorboards to the outside, plus any air leaking windows is what is keeping the house dry.If you do have it done, blown fibre is better than expanding foam, but you will have to check that airbricks and below floor openings havent been compromised.Anything that makes it more airtight is also a risk for causing damp and mould in these houses.

Bob Roberts ● 1372d

With wholesale national encouragement to 'install better insulation' in our homes, and with a whole industry likely to be built on the back of it, I can't help thinking what a shambles it could all so easily turn out to be if not done properly.

Peter Evans ● 1372d

Peter - that is what already has happened with cavity wall insulation.If insulating our homes was so easy I'm sure it would have all be done satisfactorily a long time ago.  It isn't - it is fraught with problems.  The professionals are having problems and experimenting with different ways of achieving this successfully.  The problem seems to be "thermal bridging".

Philippa Bond ● 1372d

...but there's no excuse for new homes not to be built to far higher standards of insulation and energy usage - except for developers being set in their profit making ways.

Peter Evans ● 1372d

Peter:  Yes, there are also flats - new ones - which are too hot in summer.  They obviously need mechanical ventilation.  Developers should have been building better for quite a while.The French Govt has announced they are bringing in a law to say that car parks should have solar panels on their roofs and seeing the problems that leisure centres are having with the costs of heating it makes you wonder whether they wouldn't also be good places for these - if possible of course.

Philippa Bond ● 1371d