On 19/10/2019 16:00, Another John wrote:
As the nippy evenings and cold nights become more frequent again, I'm
once again thinking about insulating the garage ceiling.

- The garage is roughly 6m by 4m, and our bedroom is above it.

- The bedrooom often feels rather cooler than the main house
(admittedly it's a big room, therefore "airy").

- Yes. I know that bedrooms are supposed to be cooler than the rest of
the house, but I'd rather achieve that by turning down the radiators.

- I keep thinking about sticking (say) 50mm Celotex boards to the
ceiling [of the garage], using mastic of some kind.

If the garage is used as such then you should have a 30 min fire break
below the new insulation.

- Would it be _worth_ adding more insulation? When built, 25 years ago,
as an extension to our semi, the joists above the garage were packed
with insulation before the plasterboard was fixed. We also have a
roller door fitted, therefore pretty good insulation at that end.

You may get a bit of cold bridging on the joists... how much difference
it will make is a harder call. However if the garage is relatively
clear, then its a easy enough job once you have worked out where the
joists are - you can screw through the new PB and the insulation in one
go into the joists to fix it.

- The whole house is very well insulated in the roof, and also with
cavity wall insulation.

Any comments would be welcome, to help me with this decision!

I helped a friend do a garage conversion some years back. One of the
comments was after the work that the bedroom above was now much warmer
as a result of now having a heated space below.


--
Cheers,

John.

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