cavity wall insulation

30 Jan 2004
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United Kingdom
I am thinking of getting cavity wall insulation put in my brick built (1961) detached villa. Have been informed from friends that it causes dampness due to lack of air in cavity. Is this true?
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If the friends live in the same area/house type/ as you and they get damp through...........then yes, it must do :confused:
raittser said:
Have been informed from friends that it causes dampness due to lack of air in cavity. Is this true?
It's mostly likely the damp is bridging across the wall tie
Does this mean that every house with cavity insulation gets damp?

Has someone told building control about this?

Are your friends experienced in building in any way? If not, you can politely ignore them
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^woody^ said:
Does this mean that every house with cavity insulation gets damp?
I don't think so, only a small number of properties, my theory is how many houses are not insulated correctly, I have replaced many windows in my time and was shocked I couldn't see any insulation in the cavity in some of them when windows are taken out. The other problem I'm seeing is the bottom of the cavity is full of mortar dropping just over the dpc level and the foam can only rest on top of it so damp could bridged across to the inner wall, doesn't happen today as they use insualtion slabs

My gut feeling is not enough ventilation as the room is now warmer which increased condensation problems
I haven't found that. I had mine done with blown glass fibre fluff, it has some kind of silicone treatment and won't hold water or get damp as it is not "wettable".

I had a bit in a bin, it filled with rainwater, I lifted out the fluff and it was dry (not damp like cotton wool).

I heard they don't use injected foam any more, is that true? there used to be stories about it shrinking as it set, and cracking, and water travelling up the cracks by capillarity.
indeed, John, it`s not been used for years.......and was allegedly sanctified for use by Satan as an enema pope Pius MCMXLVIII :eek: it was that bad a substance :mad:
I personally favour blown mineral over foam and poly beads. As JohnD says, it does not hold water and is the least likely to cause problems.

I think you will be ok as long as the contractor is experienced and they carry out a survey before installation. The contractors I have been involved with have learned that unsuitable cavities can cause problems so if the cavity isn't right they just will not proceed.
A handy tip is to ask your suppliers of Gas and Electricity to quote.

They usually have schemes at a good price (they may be under an "incentive" by the regulators) with special offers at times, and in my experience they take care to do a good job as they have a reputation to maintain. I got mine this way, they used a sub-contractor that was a very good local firm, and I had the local manager drive round for a quality and satisfaction check. I also got a long guarantee.

In the event of problems you can be sure they wil not run off with your money, or go bust.
Over the years blown fibre insulation has been discredited in the building industry because over time it tends to settle at the bottom of the cavity and compress, due to rain penetration through the external leaf therefore rendering it useless.
I also have reservations about the wall survey of the 80'ish year old house. Cavity walls did not come into general use until the 1920's/30'. This should be rechecked.
Hi All,
I'm just in the process of deciding whether to insulate or not and what type of insulation to use. - All advice appreciated especially from those who've 'been there and done that'.

Another problem I have is to actually get anyone round to survey the house.
The first couple of tries were from exhibitors at the H&R show at the NEC.
They promised to get back but never did.

I've just tried a 'google' candidate who has also not shown up (yet).
They 'lost my address / phone number'!

Lastly, I've noticed lately that B&Q are offering a service, anyone got any views / experiences of that please?

Colins 2

You want to get in touch with the New Home Inspectors. They should be able to highlight any problems.
These can be sorted before you put the house on the market.
Anyone wishing to buy your property can see its in tip top condition.
Gives you an edge on someone who hasn't got one.

They should be in the book.


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