Cavity insulation - worth it?

[topless_mx5]

My parents have had a quote today of £230 to have cavity insulation done. Its a 4 bed detached house. The price is obviously subsidised as they claim it would normally cost more than £700.

I have managed to talk them out of it. Our current electricity and gas bill comes to around £75 per month. I've estimated that £45 of that is probably gas, of which around £20 max would be heating.

Even if we get a 20% saving (considering we already have loft insulation and good windows and doors) I estimate we would save around £3-4 max per month.

So it would take at least 6 years to get the £230 back.

Am I wrong in my estimations and is it really worth it for £230?

[Mars]

I am struggling with the same concept. My father, who used to be a technical director of one of the major house-building companies, is sceptical also. His take on this is that your cavity ought to be filled with nothing but air because if you put rockwool into the gap, it will retain anymoisture that finds its way into the gap. Whereas, an air gap is free to dry out.

However, he accepts that new builds all have filled cavities (ooer), and that there must be more to it that just politics.

So, we had this quote (same as you) but being an engineer I wanted to know how they planned to pipe this chopped rockwool into a gap which is anything but smooth. The first time a pice gets hung up on a sticky-put piece of cement/mortar it'll cause a blockage. The explanation was that they pipe in polystyrene balls. I had to concede that that sounds a reasonable filler.

So I'm still deciding... £190 (we've had a lower quote than you) is a lot of heating over a number of years but we are planning to sell-up and move soon. Having cavity insulation seems a useful thing to have when encouraging potential buyers.

[agentsmith]

Parents had it done , and that combined with the loft insulation upgrade 12", instead of about 4", their house is incredibly warm all year round. I think they paid about 250 for both under grant.

in my house I had the loft insulation upgraded and think it was 110quid - again, major difference. Combined with a new energy efficient boiler our house is noticably warmer and uses significantly less gas.

[Merritt]

Have a good look around to see if you can get a government grant for it... I know of a couple of people who live in older houses that have had to pay nowt because it apparently helps save the environment!!

[Spiritual_Beggar]

yes its worth it from the simple fact that if they wanted to sell the place it will make a big difference.

improve the value and will probably make a quicker sale as well, as in the current climate people sem to be looking at how green buildings are.

[Spiritual_Beggar]

yes its worth it from the simple fact that if they wanted to sell the place it will make a big difference.

improve the value and will probably make a quicker sale as well, as in the current climate people sem to be looking at how green buildings are.

plus, thats a blooming good price!!

[topless_mx5]

I'm fairly sure it is a govt grant which makes it £230.

They aren't planning on selling any time soon. I suppose one argument could be to take advantage of the subsidy while we can, but I'm just not sure how much difference it will make to our bill.

[Busamav]

I would go for it.

Just had a 1936 property insulated .

I used blown fibre , and would NOT use polystyrene beads

[sniff diesel]

Had mine done 3 years ago, can't say I've noticed a difference in warmth or bill savings.

[GreenDog]

My dad had it done and definitely noticed a difference, and as said above a property sale at a later date would be made easier. Worth it I'd say.
Check out if Warm Zone is available locally to you, they quoted me £100 for wall cavity insulation and the same again for loft insulation.

[Simpo Two]

My cunning plan is simply to heat the cavity... that way the house cannot lose heat and the cavity is s tiny fraction of the volume of the house, so cheaper to heat

(C) Simpo Two

[GingerBaws]

I did it last year, between that and loft insulation its making a big difference to both my bills and the warmth of the house....here was the bill I got from the first full quarter after it was installed:


In case you can't figure that out, it points out in the same quarter a year earlier I used 3.5 units a day, I now use 1.76

Edited by GingerBaws on Thursday 28th August 19:27

[Snake the Sniper]

I'm in the process of redoing my loft due to the old stuff having gone flat and pretty much disappeared. I've only done half of a 2 bed house so far because I'm lazy and we had to turn the heating off as we were having to sleep with the windows open! Still do in fact.

[jeff666]

had ours done feels warmer, the walls arent so cold in winter,

[Zad]

Is it worth it?

Short answer: Yes
Long answer: fking hell yes

My parents have it and the house is always warm and dry, it is not uncommon even on cold winter days not to have any heating on, simply because it keeps the warmth in. The neighbours' house felt cold and clammy even in summer, until they got it too. To me it is a no brainer, it really is that good.

[topless_mx5]

Wow that bill has swayed me to let them get it done. Seems worth it in the long run especially with help it give when selling.

Thanks

[Trevelyan]

Be wary of the polystyrene beads. My parents had it done in their place a few years ago, and after a while the glue which bonds the beads together deteriorated. Now wherever there is an opening into the cavity (if they remove an electrical socket to decorate for example) the beads all drain out of the cavity into the room. There are also signs that they're finding their way into the floor voids where the gaps around the joists are.

The polystyrene beads also react with the PVC insulation of electrical cables and bugger it up. Make sure that you haven't got any cables running in the cavity. My parents are currenly looking at a full rewire which isn't going to come cheap...

I thought that blown fibre or injected foam was the way things were done these days?

[jules_s]

One downside is if you have 'dirty' wallties.....cavity fill will/may allow water track back across the cavity and into the inner leaf. You will then have damp spots on your walls.

Obviously this isn't great if the property is relatively 'old' as the ties may well be rusting already....

It's also worth while mentioning that there is a specific section in the building regs which covers the use of (amongs other things) the use of cavity fill, there is a map in there which details areas where driving rain may cause issues....It also covers the style of pointing which could/should be used.

So not as straight forward as it seems, I once watched a video of a cavity with wind driven rain hitting the outside.....It was like a shower in there

[qube_TA]

sniff diesel said:

Had mine done 3 years ago, can't say I've noticed a difference in warmth or bill savings.

Helps if you close the windows!

[Oilchange]

now you see thats the problem, I go out to work and come back to find all the blkoody windows open.

ventilation is the excuse, I just dont see the point if she leaves the place looking like a collander...