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Cavity wall extra insulation

Hi, our house (as built 30+ years ago) has polystyrene blocks in the cavity, and there is an air gap of about 25 mm.


Recently a company has been round as part of a "govt. initiative" offering (free) extra insulation to fill the gap?


I was always advised "never" to fill in the cavity wall completely. Not sure if its a scam as no money has been requested. Just wondering if this is the right thing to do?


many thanks
.."It's everybody's fault but mine...."

Comments

  • Furts
    Furts Posts: 4,474 Forumite
    Your house is a puzzle. 30+ years ago partial cavity fill was rare and I suggest the gap should be 50mm. Regardless, leave the gap unfilled because it is there for a purpose.
  • Stubod
    Stubod Posts: 2,652 Forumite
    Part of the Furniture 1,000 Posts Name Dropper
    .hi and thanks for the reply.....yes gap should read 50mm.

    I also understood that the gap is there for a reason...it just seems odd that somebody would like to fill it for free?


    Interestingly the neighbor (same house build) has had it done and the company turned up in an old van with no company name, logos or telephone numbers on...just seems a bit "iffy" to me?
    .."It's everybody's fault but mine...."
  • Furts
    Furts Posts: 4,474 Forumite
    Your home is way beyond the NHBC 10 year warranty but drilling and injecting is 100% against NHBC rules. Since this is a standard reference for all home building take the hint, and do not do it. As for your neighbour, I am left at a loss for words. Who with any degree of sanity allows door to door knockers to cause damage to their home? But they have also made their home unsaleable - no Surveyor will sanction what has been done. So what happens when they try to sell?
  • Don't do it. Lots of horror stories out there about these kind of jobs causing damp issues - the gap was left for a reason.


    "Company" doesn't care, all they need is anything to fill with insulation so they can tell the government they've made your house warmer and get paid.
  • molerat
    molerat Posts: 35,748 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    Furts wrote: »
    Your house is a puzzle. 30+ years ago partial cavity fill was rare and I suggest the gap should be 50mm. Regardless, leave the gap unfilled because it is there for a purpose.
    I am sure in the 80s & 90s they were throwing up block inner walls with 1" polystyrene sheets attached then the outer brick or block skin leaving a 1" gap.
  • Furts
    Furts Posts: 4,474 Forumite
    molerat wrote: »
    I am sure in the 80s & 90s they were throwing up block inner walls with 1" polystyrene sheets attached then the outer brick or block skin leaving a 1" gap.

    Jablite was one of the early partial fills and I first came across this on a 1981 building. But this was high spec build for a hospital, and private homes were a generation behind this.

    Jablite is a poor product for cavity fill, relative to PIR which seems to have come along after. If you know of 25mm sheets these would have been a nightmare to install - which means the build and insulation is going to end up iffy.

    With OP's home being 30+ years old partial fill is an unusual case, or at least in my region of the UK.
  • Stubod
    Stubod Posts: 2,652 Forumite
    Part of the Furniture 1,000 Posts Name Dropper
    Hi all and thanks for the feedback. I have contacted our local council and they have advised that these schemes are ligit....just a bit concerned about the technicality as to whether or not you should actually "fill in" the gap?
    .."It's everybody's fault but mine...."
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