Cavity Wall Insulation

[thesshhh]

Is it ever wrong or inadvisable to get cavity wall insulation on your home?

[TonyV]

No can only save you money providing it's properly installed.

[Old_Geezer]

Yes. When you have solid walls.

[Buenchico]

Cavity wall insulation should NOT be used in walls which are regularly exposed to wind-driven rain (or where the brickwork is poorly maintained), as it can lead to damp problems:
https://www.which.co.uk/reviews/insulation/article/cavity-wall-insulation/cavity-wall-insulation-damp-problems

See also
https://www.bbc.co.uk/news/uk-wales-42165358

[Arrods]

Some years ago, we took advantage of a free British Gas offer to have our loft insulation upgraded and cavity wall insulation installed. The surveyor was happy about the former but would not recommend the latter. It was because the mortar in the brickwork had been 'gouged' out deliberately for aesthetic purposes. This left a step in the mortar allowing moisture to rest there. Never took it any further, just relied on the advice.

[david small]

If know several people who had to pay to get it removed as it bridged the cavity gap and caused damage and damp.

[The Builder]

Yes, it can be inadvisable, as Chris's link shows. NHBC, among others, provide a map of the UK showing areas of extreme rainfall, and more importantly, exposure to high prevailing winds.

Most of us aren't included in these areas. In which case, there is no problem.

Cavity walls are widely misunderstood. The outer leaf is designed to be damp. It's what it's there for. There's a load of unjustified hysteria over damaged "pointing". Yes, it can slow the passage of water to the cavity, but the fact remains that the outer leaf is not a barrier.

The other consideration is the age of the building. Years ago, before the advent of thin profile stainless steel wall-ties, great big, clunky, galvanised ties were normal. These things invariably stored mortar droppings during the build. Adding cavity wall fill to these often resulted in damp migration.

So... what's your weather like, and how old is the house?

[Zacs-Master]

If you live in a terraced house!

[The Builder]

Ha ^^^ terraced houses are done all the time, Zacs ;o)

[Zacs-Master]

How doesn't the insulation 'spill / flow' into next doors cavity, TB?

[The Builder]

Good question, Zacs ;o)

Quite easily, actually. They take a brick out high up, and one near the bottom.
They feed in a snake-like barrier, through the top end, until it reaches the bottom.
Also used horizontally if it's an upstairs flat for instance.

[Zacs-Master]

Clever. Cheers.

[david small]

Galvanised ties eh. Well The Builder I’ve learned something about older cavity wall problems. My property was built in 1878 so that explains things.
You certainly know your business. I’m glad that you use this site.

[The Builder]

Well, what a compliment. Thank you for that, David.

1878? A little early for cavity walls, maybe. Although they were around in the 1800s.
Early ones were stone walls where "headers" were long stones laid perpendicular to the building.
These tied inner to outer leaves. I guess, being the industrial age, it wasn't long before steel was introduced.

Thanks again. :o)