Cavity Wall and Loft Insulation Woes

AndyJC_2

Hi Folks


Searched before posting but couldn't find any threads relating to my specific issue.

I moved house last year from a Victorian house to a newer build, detached house (circa '72), with cavity walls. The old house took a long time to warm up and cooled down quickly which was understandable due to the solid walls. However, in the new house, when the temperature started dropping, I found that the new house with cavity walls and more efficient heating was no better. For this reason I decided to get BG in to insulate walls/loft under their free insulation offer.
After their visit I was disappointed to hear that a) there was evidence of previous cavity insulation (drilled/filled holes) and b) I already had 100mm of loft insulation which is "adequate". So for these reasons they couldn't offer me anything! I found this extremely frustrating as I was pretty sure the CWI insulation was no longer doing its thing and the loft insulation is around 170mm less than the recommended amount. The BG advisor even admitted it was stupid that if I had no LI they would lay 270mm for free but as I had 'some' they couldn't help
As for the CWI, I thought I'd investigate myself by purchasing a boroscope and checking the walls. The results were as I suspected; in both the areas I checked, the rock wool insulation had slumped with obvious voids. Fortunately I had the CIGA warranty from the previous owners showing the CWI was installed in '98 so within the 25 year warranty period. Great! I thought, at least I can get this sorted without any additional costs! However, after CIGA arranged for a chap from the insulation company to inspect (original installer's no longer in business, surprise!), he drilled around 20 holes but couldn't find any obvious voids. He seems like a genuine guy but I still find this a bitter pill to swallow. I do intend to check the holes he's drilled myself when it stops raining, which might not be anytime soon!
So I am now left with a house that takes ages to heat up and no time to cool down, certainly in comparison to my girlfriends house which is of similar build & age that has had CWI recently installed.
I am no expert in these things but do take an interest in energy efficiency and have an old skool 'O level' in physics so would hope I know I little more than average.

I can't settle for the current situation so any advice offered regarding my next move with either of these subjects would be really appreciated.


Thanks


(sorry for the long post!)

Doozergirl

Most of your heat will be lost through the roof.

Remove the loft insulation and get another energy company in to assess? Or just do the insulation yourself? It's not pleasant, but it's not a skilled job.

Ultimately, free is good, but you will save whatever you might spend on cheaper bills. Loft insulation is the first measure to pay for itself in savings.

saveallmymoney

Having done a lot of eco-renovation on my 70's built house I can comment that the construction was very poor.

• Where the first floor joists went into the walls there were huge gaps around them, without cavity insulation being complete a howling gale was going under the floors.

• Although upgraded to UPVC the windows were very poorly fitted, with no expanding foam around them

• At every opportunity, there seemed to be holes to the outside. Fitted wardrobes with holes behind into the loft, soil pipes, water pipes and cables with holes cut far too big.

• I had hanging tiles on the outside of some of the house, covering only a single blockwork layer. Project to Fix

• The loft insulation had been upgraded, but fitted poorly with lots of gaps, and not to the required thickness. You can never have too much loft insulation

I found and fixed all these issues with a Thermal Camera addon for my iPhone. Flir One

Davesnave

I took all my old loft insulation out and BG are replacing it this spring, but I'd warn that anyone thinking of doing this may need to find some way of disposing of the old, because many councils, including mine, aren't pleased to see it these days.

The cheapest way to do it here is to take it to the [STRIKE]tip[/STRIKE] recycling centre as trade waste, where it will be weighed and charged at the lowest weight. Around £100.

I guess it depends where you are, but even without loft insulation, I wouldn't say my house is cold at present, thanks to a very mild winter. Last year it got a bit parky, but then I had a ceiling/wall or two missing at times! My house is the same age as yours and the CWI is far from perfect either.

Maybe the way I heat my house is different from the way you do yours. As we're in most of the day, we run a wood-burning stove slowly, but continuously, augmenting this with bursts from central heating as and when. The house therefore never cools down.

patman99

If you replace it yourself, you do have the option of using the much better stuff with foil on both sides. A 100mm layer of this is equal to 300mm of rockwool and you can board over the top to add even more 'insulation' (and a useful storage area).

Smiley_Dan

patman99 wrote: »

If you replace it yourself, you do have the option of using the much better stuff with foil on both sides. A 100mm layer of this is equal to 300mm of rockwool and you can board over the top to add even more 'insulation' (and a useful storage area).

More like 150mm assuming you're using PIR/PUR.

I'd not use a cold loft for storage at all really. Just give it 400mm+ mineral wool to get you to about U=0.1, fix all air leakage, treat the eaves correctly.

AndyJC_2

Thanks for the responses guys.

I've kinda come around to the fact that I'll have to pay to insulate the loft. It'll cost around £100 to top up with 150mm. Just a bit frustrating that I bought subsidised insulation for the last house costing £30 for the lot.

Cheapest I've found so far is Wickes. Does anyone know of a good deal on 150mm? I need around 35m squared..

Davesnave

Smiley_Dan wrote: »

Just give it 400mm+ mineral wool to get you to about U=0.1, fix all air leakage, treat the eaves correctly.

.....And then pray that you don't have to go up there to fix something! :rotfl:

Kiran

Get the 170mm rolls from wicked but don't forget to insulate your loft hatch otherwise you'll get a thermal bridge. Also make sure the eaves are clear and you add soffit ventilation if there isn't much now.