'Hard to Treat Cavity' insulation

andyv2015

Hi, I'd like some advice on cavity wall insulation for my home. The cavity is classed as hard to treat, as it's only 25mm wide, which means it isn't suitable for the standard types of cavity wall insulation installed for free by energy companies.
I have found a company that provide a different type of insulation, which is called 'Closed cell rigid PU insulation and stabilisation foam' using Isothane Technitherm foam.
Has anyone had this installed in their home and if so did you see a benefit in how warm your house is / reduced heating bills?
I ask as it's not cheap to install, my quote is for around £1700!!


Any advice would be much appreciated.


Thanks
Andy

Farway

I have no experience or knowledge of this insulation, but a gut feeling is that the payback time is just not worth the cost of it

footyguy

Wall cavities aree typically about 75mm-100mm. (some older ones may be 50mm)

So yours is only 25%-33% of the norm.

This article explains the average fuel savings one could expect with typical cavity wall insulation.
http://www.energysavingtrust.org.uk/domestic/cavity-wall
Yours will be much less because of the much smaller cavity you have.

You would be wise to consider insulating them like you would a solid wall.

andyv2015

Many thanks for the advice farway and footyguy.
It does seem a lot to pay out if the reduction in heating bill will potentially be less than £100 a year.


Any idea how much more benefit external wall insulation will provide as opposed to filling the cavity? I've read this can cost over £8000, so the payback on that would be too long also.


Although I guess if the house generally feels warmer with the insulation that's worth something too as well as any saving on heating bills.


Many thanks

footyguy

http://lmgtfy.com/?q=how+much+is+solid+wall+insulation

According to the Energy Saving Trust, the total cost of paying a company to install internal solid wall insulation ranges from about £5,500 to £8,500, while the savings on offer to the average household are around £460 a year.

Based on these figures, it would therefore take about 12 years to recoup the cost of installing internal solid wall insulation throughout your entire home.

External solid wall insulation, on the other hand, costs between £9,400 and £13,000 to install and enables a typical household to cut its annual bills by £490. The time taken to recoup the cost of installing external insulation is therefore longer at just under 20 years.

You may, however, qualify for a grant to help cover the cost of solid wall insulation. And having insulation in place could boost the sale price of your property if you ever came to put it on the market.

http://www.moneysupermarket.com/gas-and-electricity/solid-wall-insulation/

Smiley_Dan

Normally talking about £100/m² for EWI.

Don't call it "solid wall insulation". It's not. It's "external wall insulation". It's insulation for walls. It works whether you have cavity, solid, timber framed, cob, whatever walls. The pernicious rebranding of the stuff by EST and the Government make people think it's only for solid wall properties. I'm afraid to say most of us will need EWI if we are to hit carbon reduction targets, because CWI in standard width cavities is not up to the task.

But yeah, it's dead expensive, partly because of the market manipulation by government.

There are other advantages. It forms a better air barrier to improve air tightness, which is a really big problem in cavity wall properties. And that brings me to another thing: you need to work out what to do with the cavity you do have, because there's potential for thermal bypass in that narrow gap. Employ an architect or building designer with experience in low energy to design this out. It may need to be filled in another way.

footyguy

Smiley_Dan wrote: »

..Don't call it "solid wall insulation". ...

https://www.moneysupermarket.com/c/customer-care/

I don't think moneysupermarket.com read this forum, despite them owning it.

Smiley_Dan

It's a general point to everyone/thing that misuses the term - EST, Green Deal, the gubmint, whoever.

andyv2015

Thanks footyguy. Think I've missed the green deal grants now, homily they'll repeat them again.

Thanks all for the advice.

Andy