Poorly insulated 60's house with 80's front extension
Information, help, tips and advice on cavity walls, ceilings and lofts etc....

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randomdiyguy
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Poorly insulated 60's house with 80's front extension

by randomdiyguy » Thu Sep 08, 2022 3:36 pm

Hi All,

I have a ~1960s house with a ~1980s small front porch extension (downstairs toilet / bigger hallway), which gets really cold in the winter - especially draughts from downlights in the toilet. Access is very limited without making a big hole (just looking through downlight at the moment) but I think what I have is the image on the left. There's nothing between the rafters, some kind of plastic sheet (vapour barrier?) above those, then an unknown amount of fibreglass insulation...

At some point the soffits have been replaced with vented uPVC ones (no idea what they would have been originally), and what I think is happening is the cold air comes in / warm air goes out through the vents and UNDER the insulation, so it's effectively useless!

What I'm thinking of doing is removing the ceiling to gain access, taking out the vapour barrier and old insulation, replacing with plenty of new stuff, right down to the (new) plasterboard and out to the wall cavity.

Does this sound like a reasonable idea? Do I need to replace the vapour barrier, or would that be redundant in this setup? Do I need to vent at the top? (The sloped roof extends above the front of the garage to one side, which is completely uninsulated - not sure how much space there is above the side wall between the two... maybe this is a big enough 'vent'?)


Apologies for the double question, but the original front wall of the house (based on others in the road) was tiled above the front door to under the window above, so I'm assuming there's no proper cavity wall here (I can't see until I rip things out). I think that's contributing to the room above being cold - can I just slap a board of celotex over that area from within the roof void, or do I need to do something more advanced?!

Image attached to hopefully explain what I mean....

Thanks in advance for any advice / suggestions!

Ian
Attachments
Roof.png

stoneyboy
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Re: Poorly insulated 60's house with 80's front extension

by stoneyboy » Sat Sep 10, 2022 9:56 pm

Hi randomdiyguy,
What you propose should be ok but do fit continuous vent strips above the cavity so you do not seal the roof space. Also stick the Celotex onto the wall using sticky foam so it seals the gap between it and the wall.
Regards S

randomdiyguy
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Re: Poorly insulated 60's house with 80's front extension

by randomdiyguy » Sat Sep 10, 2022 10:19 pm

Hi,

Thanks for the response and the advice - can I just clarify the vent strips? Is that something I can buy or do I just need to make sure the air can circulate through the soffit vents and into the roof void?

stoneyboy
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Re: Poorly insulated 60's house with 80's front extension

by stoneyboy » Sun Sep 11, 2022 9:41 pm

Hi randomdiyguy,
Have a look at manthorpe G502 continuous vent strip. It's intended to fit on the top of the rafters but with its concertina shape you should be able to cut it into sections and staple gun it into the side of the rafters to keep it in place.
Regards S

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