Insulation in 1970's Very Cold House
Information, help, tips and advice on cavity walls, ceilings and lofts etc....

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ratinthekitchen
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Insulation in 1970's Very Cold House

by ratinthekitchen » Thu Jan 19, 2023 5:42 pm

Hi, came across this old thread and the post with the photo from paulca is my situation as well (original topic here: insulation-in-1970-s-chalet-style-house-t49352.html). My house is so cold it makes me want to cry. Don't know paulca if you did anything but any ideas please.

My house is detached but essentially the same
- Dormers built into roof (no insulation in front or sides)
- Flat dormer roof (no insulation)
- Sloping roof leading to sloping bedroom ceilings (no insulation)
- Small loft space used as storage (boarded with some, but inadequate, insulation under boards. But even if it was better its essentially useless as the heat just gets out elsewhere)

What on earth should I do. Can I remove the dormer cladding and insulate underneath and replace. Do I need to remove the roof tiles, insulate under between the rafters and replace.

Or could I try retrofitting insulation from inside i.e. remove ceilings and wall plasterboards, insulate under and then reattach (or just use insulated plasterboard) and replaster. As the loft space would still be cold internal sounds best right?

Any help appreciated.

stoneyboy
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Re: Insulation in 1970's Very Cold House

by stoneyboy » Sat Jan 21, 2023 12:27 am

Hi ratinthekitchen,
Your last proposal will be the most effective, remove plasterboards, insulate between and below joists/rafters then fit plasterboard.
Regards S

paulca
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Re: Insulation in 1970's Very Cold House

by paulca » Thu Jan 26, 2023 12:45 pm

Hi!

Firstly, I took care of the cheaper and easier options. Air leaks elsewhere. I sealed a few holes in things like the airing-cupboard that used to hold the hot tank had a huge opening into the new vented attic. The PVC doors had their catches adjusted to pull harder onto the seals. I replaced several expired and missing seals. I put floor insulation down in the electrical cupboard and filled the holes in the floor for cables with firesafe expanding foam.

This made a surprising amount of difference to the whole house, including the bedroom which is each enough to heat to 18*C after letting it sit cool all day. Even when it got down to -3C here, the bedroom wasn't using the heat all day like it used to.

I did have a builder come out (a known local reputable one). The estimate came back at around £2300. 2 days work. His approach was, as above, remove the inner plaster board from the window front to get access to the dead space, line the dead space attic in 30cm of rock wool, seal the floor joists for the cieling below with rock wool, line the back of the plaster board with insulation board and re-skim.

It had an optional estimate of around £300 to remove the stair hallway cieling and replace it with insulated plasterboard and skim.

I haven't taken them up on the offer yet. That kind of money needs budgetting.

stoneyboy
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Re: Insulation in 1970's Very Cold House

by stoneyboy » Thu Jan 26, 2023 10:56 pm

Hi paulca,
Well done it sounds like you are getting on top of the problems, nibble away at issues as you find them - eventually all will be sorted.
Regards S

ratinthekitchen
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Re: Insulation in 1970's Very Cold House

by ratinthekitchen » Tue Jan 31, 2023 11:54 pm

Thanks for the replies.

I won't know until I remove the plasterboard on the ceiling and dormer front/cheeks what gap there will be to insulate in but I would reckon not a lot. I'm guessing you mean use something like Kingspan? But don't I need to leave a 50mm airgap so I doubt I'd get much if indeed any insultation in. Insulated plasterboard may also be an option but this is obviously thicker and my rooms aren't that big and the ceiling is low so I don't really want to lose any space.

This might be the world's daftest question but I'm going to ask it anyway. If you use sheepswool insulation do you still need an airgap or can you fully fill the void. Isn't it supposed to absorb moisture in winter and dry out in summer or have I missed the point of the marketing pitch!

stoneyboy
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Re: Insulation in 1970's Very Cold House

by stoneyboy » Wed Feb 01, 2023 11:05 pm

Hi ratinthekitchen,
You should be ok leaving a minimum gap of 25mm - insulate between any roof timbers and over the top, use insulating boards with a low lambda number.
Wool will, as you say, dry out but only if there is air circulation over it, so stuffing the roof recesses full would only lead to damp being retained.
Regards S

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