Cavity wall insulation

[davek_964]

I rent a property out - which is EPC D. In a few years, that will be a problem (if I decide to keep it). One of the proposed changes to get it to C is cavity wall insulation.

My only knowledge of that is horror stories I've seen where it gets wet and causes damp. As a result, I've always thought it was a very bad idea.

I assume I'm wrong and there are plenty of positive results? Are there different types, and some work better than others?

[OutInTheShed]

The main things which make CWI a good or bad idea are the wall finish and the location of the property.

Porous brick exposed to atlantic weather, it's a bad idea.
A rendered and painted wall in a sheltered spot, much less chance of trouble.

[PaulWoof]

Dont know the full knowledge of it but i think there are a few variables. width/cleanliness of the cavity, condition of outside render. With the primary risk being if the insulation gets wet, its not going to get un-wet...

i bought a house that has had retrofit cavity wall insulation sometime in 2009. it was a slight concern of mine but has went through a couple home reports with no identification of damp and nothing i can find. I dont know what type it was wether it was the blown in beads etc but it seems to be doing its job for a 1950s house and a few people have commented it feels warm for a house in the middle of a field.

the other risk is insulation companies to have a habit of pheonixing regularly, it seems the loft spray foam lot have had the audacity to morph into spray foam removal companies from what ive seen

so by the time any issues materialize the chances help are pretty slim. i have a 25 CIGA gaurantee but even then i dont know if it will do any good if i do have any issues.

[davek_964]

OutInTheShed said:

The main things which make CWI a good or bad idea are the wall finish and the location of the property.

Porous brick exposed to atlantic weather, it's a bad idea.
A rendered and painted wall in a sheltered spot, much less chance of trouble.

Hmm - unfortunately, I fall into the first of those........

So far, it looks like my view of it is probably mostly right - in which case, I don't think I'd be willing to risk it. There is supposed to be a cap on how much you spend trying to get to EPC C - I'll waste my money on other pointless things that at least won't cause future problems.