Cavity wall insulation

hornetstinger · 8 Mar 2018 at 22:32

House is 1900 era, semi detached. Report came back that it has 200mm loft insulation, but no cavity wall insulation.

I heard you can get damp from cwi is this true? Pros and cons?

SPG · 9 Mar 2018 at 09:00

I would be very surprised if you could actually have cavity wall insulation on a property that old.

If you mean external cladding, if not done correctly then damp can happen, old houses like it if they can breathe, downside to this is they are a little more expensive to heat.

Martynt74 · 9 Mar 2018 at 10:55

We had this done about 6 years ago in our victorian terrace and we've not had any issues with damp so far. Not sure if there are any reasons why some would/wouldn't

It definitely made our house a lot warmer and keep warmth in as it used to get quite cold once the heating shut off. If anything i now complain it's too hot most of the time!

Ours was through the grants available back then. Not sure if they're still available or not.

a1ex2001 · 9 Mar 2018 at 11:32

As above I'd be very surprised if a Victorian era house didn't have solid walls making cavity wall insulation impossible, as an aside cavity wall insulation can cause damp issues in certain circumstances mainly where walls are exposed to driving rain this can be minimised by the use of a brick sealant such as Storm Dry.

External insulation which is much more likely on a Victorian home shouldn't cause damp issues if installed correctly and can massively improve the thermal performance of a house be aware that it may require planning consent and will make your house ugly

Martynt74 · 9 Mar 2018 at 11:36

As mentioned. Our house was built around 1906 and has cavity walls

Also found this

Builders and architects started to experiment with cavity or ‘hollow walls’ from early in the Victorian period. By the first decade of the 20th century, most pattern books for houses included examples of outer walls with two separate leaves of brickwork.

gort · 9 Mar 2018 at 13:48

This week I had an EPC guy round to do his thing. He's been in the building game for many years and doesn't recommend CWI due to potential damp issues. Good in theory but not always good in practice.
For many refurbishments he's been involved in, he said if walls need insulating then they just fix the internal boards up.

thezappa · 9 Mar 2018 at 16:55

Perfectly possible you have a cavity. You can measure the wall thickness at the bottom and at the top as it may be a tapered cavity, if you really want to know.
Personally I’d stay away from having them filled despite what some might say. If it does go wrong and you get damp you’ll have a large bill and a pain in your backside getting it out.
You could insulate inside, aerogel is very low profile and has excellent u-values but is expensive. Otherwise the only other option is external but you then have to increase the depth of cills and soffits etc