Any reasons NOT to get cavity wall insulation?

[David Hearn]

Our 1930's semi doesn't have any cavity wall insulation and I'm thinking it might be useful to get some.

Unfortunately we have cladding on the front, and render on the side. Both are in good condition, so I'm a little loathed to have someone drill multiple holes through them. At least with the cladding, the holes should be able to be done through the mortar, rather than the actual tiles (although I guess it depends on the size of the nozzle they use).

We have mains cables which run through the cavity it seems (they leave the fuse box and enter the cavity). We also have a extractor in the bathroom which extracts through a large diameter pipe pushed up against the inside of the exterior airbrick. It isn't completely sealed, so may vent a little into the cavity.

What are the potential problems with getting it done?

What are the benefits of getting it done? Cost may be as low as £150, maybe £200 or so according to some places (no quotes yet - just looking online etc). How long would it take to pay itself off? Things are quite tight at the moment - but something like that could be useful to get one sooner rather than later.

Thanks

D

[Andy]

Airbricks need sleeves fitted to stop the rockwool or polystyrene beads being blown out.

Apparently if it's rockwool it doesn't wick damp, as it's coated cavity-grade rockwool.

I've seen £130 quoted ( try

) . How long would it take to pay itself off? Depends on your heating bills but I saw 2-3 years mentioned. That's very good for an energy-saving measure. I'm not sure I know of anything with a faster payback time. Double glazing takes twenty years.

I'm thinking of getting it done too. Also I want to top up the loft insulation. Note that with the way the grants are structured it may be cheaper to bin your existing

2" ( or whatever ) of insulation and have 10" fitted, than to have it topped up to 10"!

Andy

[Christian McArdle]

You can fill from inside. This is a good idea if you have painted walls and spare paint, as it can be easier to fill and repaint a few holes on the inside if you don't have a brick faced exterior.

PVC may leach plasticiser if encased in some insulants. Perhaps more importantly, it reduces their current capability, so it might be worth checking that they still have sufficient capacity for their intended use.

Reduced heating bills, decreased condensation (if done right) and a much more comfortable existence and more even heating. Cooler in summer.

Christian.

[David]

In article , David Hearn writes

I've just had an offer from Powergen to cavity insulate for £75 (half price offer) unfortunately I'm already done

[RedOnRed]

We had cavity wall insulation done in April. We also have wooden cladding on the upstairs. We couldn't have the insulation done where there's cladding as there isn't a wall cavity. They're cladded onto blockwork.

We had the downstairs done only, which is standard brickwork and cavity. They do drill a lot of holes and "make good" afterwards but even with ordinary brickwork it's still noticeable all the patching up they do.

[RedOnRed]

It's messy enough doing outside! Not too sure if that sounds like a good idea to me.

You have to do a massive amount of drilling with a very large hammer action Kangol like drill to get the stuff in and the amount of brick dust created is alarming. Then try getting the industrial sized filling machine in your house.

The brick dust is only just starting to disappear outside our house and we had ours done 6 months ago.

[Anna Kettle]

I had mine done three weeks ago with no mess apart from some overflowing insulation by one of the holes. I was generally pleased with the work done - tidy, pleasant, helpful workmen ... who are booked up five months ahead

Anna

[Christian McArdle]

There must be several types of machine. There is a type that involves only having much smaller holes and produces about as much dust as mounting a few pictures.

Christian.

[RedOnRed]

I suppose it's possible but certainly not ideal. I've certainly never heard of people have their cavities done from inside.

Another issue would be limited external wall access due to for example an internal supporting wall getting in the way.

[Christian McArdle]

It is certainly not the default method, but it can solve problems.

Again, you are right that it is not ideal. However, if the external wall can't be punctured without excessive damage, then the inconvenience of doing from inside is worth it, especially when there is no wallpaper to worry about.

I believe there was a case once with a cowboy contractor using such equipment who got "lost" inside the house and attempted to cavity fill the party wall, but succeeded only in filling the neighbour's built-in wardrobe. It may be an urban myth, though!

Christian.

[Matt Beard]

Similar things do happen. Many years ago, when I did computer support, I took the call from a customer who was having the building insulated and the guys pumping the insulation got concerned that it was taking a long time, so went inside to investigate. There was a hole of some kind (not sure what the cause of the hole was) in the inner wall behind the desk holding thier computer - when they came inside the computer and desk were basically inside a mound of the stuff. The computer was a right-off, but the contractor's insurance paid for it to be replaced.