Cavity wall insulation, I say yes dh says no

[WhenSheWasBadSheWasHopeful]

Looking for advice from someone who knows more about insulation than me that'll be 99% of the population

We have an old house that is fucking freezing. When you put your hand on a internal wall it feels ok but an external wall is freezing. Our brick work isn't great so we are getting the sides and back rendered (front is ok).

Once we have had the rendering done I want to put in cavity wall insulation but dh is worried about damp and says no.

Anyone have any advice?

Are you sure your house has cavity walls? They weren't standard generally until 1930s or 40s. If you have, then I'd get it done - it should massively improve the warmth in your house and I think there are masses of grants etc to bring the price down (I live in Edwardian house so no chance I can have it ).

Thanks for the post. Yes it definitely has a cavity, we had new double glazing fitted. In one of the rooms the sill had to come off and we could see into the cavity wall.

House is about 100 years old (or more) but has a cavity due to it being a coastal property and the weather is damaging to the brickwork.

British Gas have a grant scheme that ends in March where you can get all or some of it free if at least 2/3rds of the house needs it. We are getting free loft insulation. Get it done - will save you loads on your heating. Awful living in a cold house.

Yes, yes and yes. It's a very cost effective way of saving energy and it'll make your house more conmfortable.

Thanks again. I hate being cold. With this weather I've been arriving home to a 13 deg house. It's just not fair on dd (2 years old).

Our neighbours are getting it done soon and they live in an identical house. I will have to speak to them to get their opinion on hearing improvements.

Dh just keeps saying that all builders are dead against it. They keep saying there is a cavity for a reason and imagining everything that could go wrong.

Isn't the air in the cavity acting as an insulation?

I would tend to agree with your dh on this. If the insulation material gets damp because of a crack in the brickwork or render how will it ever dry out?

flatbread the air is not doing a lot in the way of insultating at the moment.

I think dh is worried about the cavity wall filling getting damp, I suggested using the (more expensive) foam ball option - then you have some ability to get it back out again if it all goes wrong.

I think we need to check we have a "clean" cavity. Not one with loads of mortar fallen in it. It's a bloody big wall, it would take ages to check it all.

lala if we don't get the cavity wall insulation we would have to look at extra insulation either inside the house or outside it. So you lose your original features in the house or the external look

I certainly would. If the wall has defects then they need to be corrected, regardless of filling with insulation.

the fibre is water repellent and it is very difficult to make it damp. However if your cavity is already wet due to defects, insulation may prevent airflow drying it out when the rain stops.

The insulation companies have a responsibility to survey and inspect the wall to verify it is suitable. If they get it wrong they can be compelled to fix it or even vacuum out the insulation. I got mine done via the electricity company, you can rely on them not going bust or running off with your money leaving you with a problem.

It makes a big reduction on heating expenses, and a big big big improvement in warmth and comfort.

While you're still deciding, it's worth checking for draughts too. If the house is 100 years old are there gaps in floorboards?

Re: insulation, is the property exposed and subject to driving rain? If so insulation isn't recommended and the guarantee they offer won't be valid - if there is a problem and you claim under the guarantee the insurer will refuse the claim because the property wasn't suitable in the first place. Ask to see any guarantee before you decide, and read the small print.

And (this may well be a shaggy dog story) a British gas engineer did once tell me a story about drilling a 4" hole for an airvent through a wall with foam beads in it, and then watching as a stream of beads covered the floor. No idea whether that's true though!

Definitely definitely definitely do cavity fill. All the old scare stories are mostly just that, materials have changed & methods are generally fine. Use one of the companies who get grants via the energy companies as they are vetted.

Check the Energy Saving Trust www.energysavingtrust.org.uk/Insulation/Cavity-wall-insulation

While you're thinking about this, check your floor too, is it timber, suspended over a void? Then you must insulate this too (relatively cheap but you have to take up floorboards. You must include a vapour barrier to stop moisture & draughts (a glorified plastic sheet). Fill all gaps at skirting boards too.

For floor insulation, "must" is too strong a word. It is much more work than Cavity or Loft insulation.

But I agree it is worthwhile if you have underfloor access, or the boards are being taken up for some other reason (e.g. to put chipboard on the bonfire

I do not agree with an impermeable plastic sheet which prevents ventilation of the timber and may encourage rot.

Hi piglet, I didn't say actual plastic I said vapour barrier (glorified beyond regular plastic! ;) ). It needs to be put over the top of the insulation but the timber joists need air flow below them.

OK 'must' is too strong but the heat-loss through a suspended floor with butt jointed floorboards can be far higher than an uninsulated cavity wall, so worth some effort.

Thanks for all the responses.

Re draughts, l've spent quite a lot of time on my hands and knees recently identifying and blocking up random draughts. So that is going quite well.

The house is subject to driving rain, I was hoping that rendering the property would fix this issue. Will have to check.

The house does have suspended floorboards, I want to carpet but dh has bad asthma and his health would suffer.

thermalkaty fabulous name. I very much hope you are right about the scare story's being just scare story's.

Would get it done if you can.....ours is 1930s house, walls have cavities BUT they are not wide enough for cavity wall insulation. We got 2 different firms out for quotes and they both said that.

Instead, we consulted a builder, and he suggested insulated plasterboard - fitted internally, on the external wall (if that makes sense). We lost about half an inch off width of lounge, but it has made a hugggge difference. Eg yesterday morning, came down at 6am, heating hadn't come in (low pressure in boiler - soon sorted) - but despite low temps outside I was able to sit and eat breakfast before asking DH to sort boiler. We are so pleased with the difference that it has made that we really want to get 2 other "cold" rooms done.

Our last house an Edwardian detached had had wall insulation recently installed when we bought it. 8 years on when we sold the house it was damp in all the downstairs rooms- not that we ever noticed, but was picked up on the survey.

I've read somewhere that it can also cause wall ties to corrode a lot quicker and ours also needed replacing.

The house was really warm though and on the strength of that my dm went ahead and got her 1940 's semi insulated, she's had an ongoing problem with mildew on the ceiling in the smallest bedroom and has had to rely on a condensation extractor thingy ( can't for the life of me think of what it's called)

If we'd known who had done our cavity wall Insulation we might have been able to claim but the vendor didn't pass on that information.

Get it done!

Our living room was freezing but now it's one of the warmest rooms in the house. We got ours for free under the British Gas scheme.

Don't do it, it has caused 10000 worth of damage to my parents house.
CIGA isn't independent it's funded by the industry. Google Jeffrey Howell who writes for the Sunday Telegraph and the Which report. Avoid the Mark Group

After they caused 10k worth of damage to my parents house I wrote to Ed Davey the environment secretary. Apparently the energy companies fund the installation by govt obligation. In other words they raise consumer bills to pay for the work so nobody saves. Also after investigating a bit more Ofgem has no concrete figures to identify complaints and problems with CWI. However energy suppliers suggest that 17% of all installations encounter problems. I would also guess that this is underestimated as no official figures are collated.

CIGA is not independent it is controlled and funded by the installation industry.

Get qualified advice first, all the 40's houses round here were done & many have significant problems with mould caused by condensation now. It's a real pain to sort.

There is a website you can check to see if your house isin an area of driving rain. Its the one thing that is,making me question doing it, especially after this winter

there is a body of opinion that Jeffrey Howell is wrong. He is a great self-publicist.

We had thought about insulation but had heard bad things about damp after it and our house was not eligible in the first round of government subsidies as it is over 100 years old and on the coast so higher risk.

We recently had a company round offering to do this on a government scheme. Their plan was to use the foam balls but apparently the newest stuff is PVA coated so are tacky and form a lattice, they don't settle as much as the old ones did. We were on the verge of signing then had a call from British Gas who are offering insulation too so we decided to get a survey from them too as a second opinion.

Their surveyor said absolutely do not do it. The house is Accrington brick with narrow mortar joints, he said there was a high risk of cracking bricks which could spoil the appearance of the house and a very high risk of damp. He also said that the amount of money saved for an average 4 bed detached house was only around £250 per year so not worth the risk

I am very keen on using a well-established company with a reputation to look after, and the resources to stand behind its guarantee. I never touch itinerant door-to-door salesmen.

I had mine done by BG, but most of the other energy companies offer a scheme. BG are currently offering subsidised installation.

The installer is responsible for carrying out a suitability survey, and can be forced to rectify or remove a bad installation if they get it wrong. It sounds like BG correctly carried out the assessment and are avoiding getting themselves into trouble.

They won't give you have the cavity wall insulation if they can't see your damp proof course. They won't let you have the loft insulation if you have a loft room, as you have to have so much insulation.

BTW the risk of cracking Accrington Reds will be that they are very hard, and difficult to drill. It is not actually the CWI that might damage them.