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Cavity wall insulation

Posted: October 4th, 2021, 5:06 pm
by MrFoolish
I had some kid, complete with clipboard, knock on my door, talking ten to the dozen about cavity wall insulation. Think he represented some private company. He was going on about grants for cavity wall insulation. But fundamentally he wasn't clear and I politely sent him packing.

So,

- How do you know if you already have cavity wall insulation?

- Is it worth getting? Who can claim a grant?

- How do you find someone trustworthy to check your home and potentially do the job?

I've looked on the web but it all seemed as clear as mud.

Thanks.

Re: Cavity wall insulation

Posted: October 4th, 2021, 5:31 pm
by richlist
You normally get a certificate if its been retro fitted.
If the house is new....or built since I think 1990 it will be fitted as part of the building regs.

Re: Cavity wall insulation

Posted: October 4th, 2021, 5:48 pm
by MrFoolish
richlist wrote:You normally get a certificate if its been retro fitted.
If the house is new....or built since I think 1990 it will be fitted as part of the building regs.


The land reg date is 1991. Guess it might have been built in 1990, just to make things difficult!

There's a single hole in the brickwork (third the size of a brick), which I think may have been an overflow for an upstairs toilet, but the toilet now drains into the bowl. It is too high up for me to look at. I have a plumber coming for another matter. Maybe I could get him to fill the hole and check for cavity wall insulation whilst he's about it?

Re: Cavity wall insulation

Posted: October 4th, 2021, 6:00 pm
by mc2fool
The primary purpose of a cavity wall is to keep the inside wall dry, and hence avoid moisture/damp reaching the interior of your home.

Cavity wall insulation bridges the cavity between the outside and inside walls, and in some (by no means all) situations leads to ... https://www.bbc.co.uk/news/uk-wales-42165358

Also see https://www.timberwise.co.uk/penetrating-damp/cavity-wall-insulation-problems/

Re: Cavity wall insulation

Posted: October 4th, 2021, 6:10 pm
by MrFoolish
mc2fool wrote:The primary purpose of a cavity wall is to keep the inside wall dry, and hence avoid moisture/damp reaching the interior of your home.

Cavity wall insulation bridges the cavity between the outside and inside walls, and in some (by no means all) situations leads to ... https://www.bbc.co.uk/news/uk-wales-42165358

Also see https://www.timberwise.co.uk/penetrating-damp/cavity-wall-insulation-problems/


Thanks. The second link says:

Is the property exposed to wind driven rain?
Is the house sheltered by buildings or trees?
Are the external walls poorly constructed or maintained?

If you are answering yes to any of these questions, then it might be worthwhile having second thoughts on whether cavity wall insulation should be installed at your property.


Presumably the house is either exposed or sheltered, so surely one of those first two questions must apply!

Re: Cavity wall insulation

Posted: October 4th, 2021, 6:25 pm
by MrFoolish
BTW, my EPC at the time said:

Cavity wall, as built, insulated (assumed)

Assumed, ha! EPCs are a waste of money (assumed).

Re: Cavity wall insulation

Posted: October 5th, 2021, 7:58 pm
by 88V8
Only a small part of our house is cavity. It was filled with blown fibre about three years ago.
No damp problems. Yet.

To get the fibre in, he drilled inch dia holes in the walls at about 4ft centres. Even though he roughly filled them in, one can see them.

V8

Re: Cavity wall insulation

Posted: October 6th, 2021, 9:56 am
by 88V8
88V8 wrote:....holes in the walls at about 4ft centres.

Erratum; looking this morning, more like 18" horizontal and 24" vertical.

V8

Re: Cavity wall insulation

Posted: October 6th, 2021, 10:34 am
by sg31
88V8 wrote:
88V8 wrote:....holes in the walls at about 4ft centres.

Erratum; looking this morning, more like 18" horizontal and 24" vertical.

V8


That sounds more like replacement wall ties. It's a bit too close for insulation.

Re: Cavity wall insulation

Posted: October 6th, 2021, 11:08 am
by monabri
look for regularly spaced round holes (1cm diameter)...

https://en.wikipedia.org/wiki/File:Fill ... ation.jpeg

Re: Cavity wall insulation

Posted: October 6th, 2021, 11:35 am
by PhaseThree
If you have an electricity meter box set into the outer wall you may be able to see signs of cavity fill around the cable entry points.

Re: Cavity wall insulation

Posted: October 6th, 2021, 8:02 pm
by 88V8
sg31 wrote:
88V8 wrote:
88V8 wrote:....holes in the walls at about 4ft centres.

Erratum; looking this morning, more like 18" horizontal and 24" vertical.

That sounds more like replacement wall ties. It's a bit too close for insulation.

I was here when he did it, deffo insulation.

Oddly enough, today I was working on my fix for blown wall ties in that same wall, a 1960s rendered block wall of a height that didn't really need ties in the first place... which involves screwing/gluing cedar planks over the crack in imitation of half-timbering, and then rendering between the cedar with a fibre-rich mix.

Perhaps this should be in the Bodgetastic thread :)

V8

Re: Cavity wall insulation

Posted: October 7th, 2021, 12:31 pm
by DrFfybes
88V8 wrote:
sg31 wrote:
88V8 wrote:Erratum; looking this morning, more like 18" horizontal and 24" vertical.

That sounds more like replacement wall ties. It's a bit too close for insulation.

I was here when he did it, deffo insulation.
V8


Never let facts get in the way of a good discussion :)

Oddly enough, today I was working on my fix for blown wall ties in that same wall, a 1960s rendered block wall of a height that didn't really need ties in the first place... which involves screwing/gluing cedar planks over the crack in imitation of half-timbering, and then rendering between the cedar with a fibre-rich mix.

Perhaps this should be in the Bodgetastic thread :)


That's a repair. A bodge would be some mastic in the cracks and shove a shed in front to hide it.

Paul (who spent yesterday afternoon fitting castors to the gates which are lovely 1.8m hardwood ones with no diagonal bracing so they have dropped and drag on the drive).