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    • henrik1971
    • By henrik1971 9th Jan 18, 11:25 PM
    • 173Posts
    • 105Thanks
    henrik1971
    Insulation advice and new extension
    • #1
    • 9th Jan 18, 11:25 PM
    Insulation advice and new extension 9th Jan 18 at 11:25 PM
    Two separate issues. Wondering if anyone has any advice:
    1. Last year we were trying to get cavity wall insulation put in to the walls of our 1960's bungalow. The company sent round their surveyor who asked lots of questions and then took his endoscope camera to inspect the cavity. All was well, but when he checked the cavity in part of the flat roof extension at the back of the property that was constructed in the early 1980's he noted some concrete in the cavity, upto about about 2-3 inches above DPC level.
    He said this meant we couldn't have cavity wall insulation as it would create a cold spot in this location which was apparently a very big problem.

    This sounds very odd to me. I understand the concept of a cold spot, but not to be able to insulate any of the elevations of the house because of a cold spot on one part of one side of the extension seems a bit extreme. Does this sound right? Any ideas about where to go from here?

    2. Wanting to enlarge the 1980's single story flat roof extension this year, to create an additional 160-180 sqft of space to create a lounge area. Going to have quite a bit of glazing. Using the additional space as an additional lounge room.
    I'm in Yorkshire. Do you think I'm still looking at £100-120 per sqft build costs excluding decs, floor coverings, etc.? Or am I well out of date with build costs? Also can anyone point me to a link online for an example contract that i can use with a contractor that provides for staged payments?

    Thanks
Page 1
    • Furts
    • By Furts 10th Jan 18, 8:17 AM
    • 3,758 Posts
    • 2,375 Thanks
    Furts
    • #2
    • 10th Jan 18, 8:17 AM
    • #2
    • 10th Jan 18, 8:17 AM
    You are fortunate the surveyor spotted the cavity problem. Cold bridging is an issue, but what is really happening is more concerning. You will have damp tracking up past the dpc, think rising damp, and also coming down the cavity through condensation and rain. This will be tracking into your inner leaf.

    Two points follow on. First CWI companies cannot install when there are signs of damp and defects. It will bounce back on their work and guarantee, and onto the CIGA guarantee. Second all home owners have a general duty of care to maintain their homes. (If one does not then they de-value.)

    The home owner should be presenting a suitable house for CWI and this includes clean cavities. Yours have not been suitably presented hence no CWI. Here the solution is to rectify the cavity, and also check everywhere else. Then try again for CWI.
    • henrik1971
    • By henrik1971 11th Jan 18, 12:34 AM
    • 173 Posts
    • 105 Thanks
    henrik1971
    • #3
    • 11th Jan 18, 12:34 AM
    • #3
    • 11th Jan 18, 12:34 AM
    Thanks for that .
    I think when I have building work done later this year, I will get them to work around the bottom few courses of bricks on the 1980's extension in small sections, cutting them out, chipping out the concrete, inspecting the dpc and reinstalling the bricks. It will probably be a few days labour, but worth it.

    One of my concerns of course was the new extension will have to be insulated (to meet building regs), but how can this happen if the rest of the house is uninsulated?

    Having said all that, the new extension is to be built on to the existing extension which will have the affect of a large section of the current external wall becoming an internal wall. Understood there is still the rising damp risk to be addressed, but an internal wall will not really need insulation anyway..
    • Furts
    • By Furts 11th Jan 18, 8:07 AM
    • 3,758 Posts
    • 2,375 Thanks
    Furts
    • #4
    • 11th Jan 18, 8:07 AM
    • #4
    • 11th Jan 18, 8:07 AM
    CWI is more technical than many folks realise. A basic principle would be to build your extension then get CWI afterwards. This means you know your new extension's insulation is to current Regulations, you can see and inspect and sign this off, you know exactly where and how it interfaces with your future CWI and you know then what walls the CWI installers will need to inject.

    There is a huge converse to this. Millions of homes will have building works, new windows, extensions and so on done after CWI was installed. All this work has jeopardised, or invalidated, their CIGA Guarantee. You do not want to be doing this - get CWI after your extension.

    Incidentally, I have CWI on my internal walls, so do not knock the concept of this! Not many folks know about doing this.
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