Cavity wall insulation and EPCs

rowan_bradley

I recently moved house into an end of terrace built in 1986, standard brick construction. The EPC said it needed to have cavity wall insulation. I had someone come and check it. He drilled a hole and pulled out some insulation. It looked like glass wool to me. He then gave me a quote for removing all the old insulation and filling it with polystyrene beads. Is it really worth doing this? How much better is polystyrene beads than glass wool? How much of the saving that the EPC said I'd get (£120 per year) have I in fact already got because I've got the glass wool? When I get a new EPC, how do I persuade the assessor that I _have_ got cavity insulation, and I _have_ got a condensing boiler, both things the previous assessor seems to have just assumed I didn't have.
Another gripe about these EPCs, why do they recommend things that have a 100 year payback (in my case adding ground floor insulation, cost £4000-6000, saving £50 per year)?

Thank you - Rowan

TheNorthStar

Personally, I wouldn't go near polystyrene beads, it's all very well insulating a property but it needs to breathe. If a property can't breathe and ventilate you will have damp problems. Glass wool will be breathable and less of a problem. I've spent a lot of time researching this regarding my own roof and now use a positive airflow system in the loft blowing cold air in from outside. Within one day of switching this on all of our damp windows dried out. It might be frustrating, but drafts are sometimes good.

Swipe

Personally, I wouldn't bother, but then my bungalow doesn't have its cavity walls insulated and I have no intention of getting them done unless I'm offered it for free. I'd be sceptical if you could tangibly notice the difference between the existing wool or the beads unless you have cold spots where the wool failed to reach if it's the blown in type. I barely noticed the difference in the two bungalows I've owned when I went from zero loft insulation to 30cm and the first one also had cavity wall insulation as well.

MWT

rowan_bradley said:

I recently moved house into an end of terrace built in 1986, standard brick construction. The EPC said it needed to have cavity wall insulation. I had someone come and check it. He drilled a hole and pulled out some insulation. It looked like glass wool to me.

The way the EPC process works, if there is no visible evidence of cavity wall insulation and you have no documentation to prove it exists then it goes down as not having it even if it does.

You now have evidence that there is cavity wall insulation...

squirrelpie

EPCs are a complete nonsense IMHO. They're planned to be replaced in 2026 with a new system based on the Home Energy Model (HEM) but as usual with anything the government is planning in relation to building, it's all as clear as mud.

rowan_bradley I'd suggest this winter you borrow or hire a thermal imaging camera and use it to see where heat is leaking out of your house. You may be able to see how well the existing cavity insulation was installed, which will guide you as to whether it's doing its job and so not worth replacing. There are various local organizations around the country that help people improve their properties and that may be able help with a thermal camera and expertise in how to use it. I'm thinking of groups like Carbon Coop and Cambridge Carbon Footprint and there are many others.

ROY47

Just paid to have the Fibreglass cavity wall insulation removed from my house its been in for 35 years or there abouts

Had damp patches in many places inside the house a lot of it was near ground level 

A lot of  what came out  was very wet , my house is typical 70s / 80s semi  . Company that took it out said we get many problems like this , house wasn't built to have cavity filled . They checked before for signs of water ingress foom roof , guttering windoows etc.  and noted that old air bricks had been covered over so not allowing house to breathe  

Spoke to guys doing the job about polystyrene  beads type   he laughed and basically said its worse than fibreglass stuff and said again  house wasn't built to have cavity filled 

That's my experience , maybe some have had better  than me 

Spoonie_Turtle

Bead insulation made our damp problems significantly worse.  It's only since having central heating installed (heat pump) that the mould has been somewhat controlled - it's still a battle but now more of a stalemate rather than us constantly losing.

[Housing Association property; cavity wall insulation was not our choice.  That said, I'm not sure I want to imagine how much colder it would have been in the decades prior to central heating with the ventilation blocks open.  I have no doubt they worked fine when using fires to heat the house from the inside out, but those were blocked up to not be an option.]

wrf12345

Doing some windows, my bead insulation had either settled down or not been filled properly but I have had it done for free on a couple of other houses and did not notice any improvement in the heat retention, both having large swathes of double-glazing through which heat escaped - I do have some homemade Celotex-based panels that I fit internally when there is no sun that help significantly with heat loss, and also whack them in when there is too much sun on the south side - house never gets above 25 degrees. Small or zero windows on the north side is probably more important than cavity insulation and may be worth changing the house's layout to make viable. I am tempted to buy a cheap, cash-only, non-cavity property and sandwich it in Celotex, if only to see if it works better or not.

Stubod

..our neigbours got "conned" into having beads installed, ddespite the fact that we had told them that our houses had already been built with polystyrene blocks placed in the cavities, but they went ahead anyway. 

Often wondered what happened to all the beads they "pumped in"... ....or whether the "supplier" was surprised how few beads had been used..

..and yes I think EPC's are largely a waste of time, administered in the main by unqualified people who have probably just completed an online "tick box" course.

Beeblebr0x

I believe cavity walls were originally built to prevent damp penetration, so to fit insulation retrospectively can be risky, particularly if you live in a part of the country that has high rainfall.

When we extended the kitchen to the side, the new side wall had to have cavity insulation, but the original back wall is single skin. Go figure!

MWT

FWIW, our house was a new build in 1987, and was built with polystyrene bead insulation from new and has been perfect in all respects. 

Nothing inherently wrong with them as an insulation method if designed for it.