Insulating single skin double garage to be comfortable workshop/garage

Discussion in 'Builders' Talk' started by LeamK, Dec 29, 2020.

  1. LeamK

    LeamK New Member

    I have a fairly big 6mx7.5m garage that I want to turn the back part of into a workshop that is going to be comfortable to use in cold weather.

    It has two old style breezy garage doors, a (mostly) plaster boarded flat ceiling with a vaulted roof over that, it also has a separate door and two windows. But no insulation anywhere to be seen.

    I've like to insulate the walls and roof to get it to retain heat when I add in a heater when working in there. However, because it is still also going to act as a garage, it needs to still be able to take cars.

    So, does this plan make sense?


    Batten walls with 100mm treated battens, spaced 600mm apart, fill with wool batts (or celotex type boards?) and then seal over with a vapour barrier sheet and finally finish with OSB or ply that I'd then paint to give me a solid surface to attach stuff to in the workshop. If I was to do that, given I'm not going to be insulating or putting down additional damp proofing or insulation on the floor, then how far to the concrete floor should I go? Should the battens go all the way to the floor? Given they are attached to the external cold wall, no harm in also going to the floor?

    Should I spray the brick wall with damp proof spray first?


    Can't decide if I should go warm or cold roof here as I've got a flat rafter ceiling and a peaked rather ceiling only about a meter above that. Given the geometry, it feels a lot easier to again put wool batts in the roof and then a sheet of vapour barrier again followed by OSB or plasterboard again. Or should I go all the way up into the peaked rafters and do the same, but at that level?


    Going to just leave as is, but might put down some rubber matting for a bit of warmth and comfort under foot at the workshop end of the garage.

    Does this make sense? Or any other approaches better?

    Photos attached.

    Thanks and appreciate any feedback.

    Attached Files:

  2. kiaora

    kiaora Guest

    Looking at the pictures, my first thought was, finish off installing ceiling boards and install a few rolls of insulation, say 400/600 deep, to form a cold roof,
    The cost would be low, and the benefits very high,

    then see how much warmer it will be, and if you need any wall insulation. .?

    well that’s my view,

    good luck
  3. AndBlue

    AndBlue Member

    Deal with the roof first as above. Are you removing & replacing the existing ceiling boards? If so, how about some rolls of insulation in joists then Celotex type board (even if its 25mm) on to the battens with taped joints to reduce drafts and then the ceiling board. Appreciate its a garage so drafts are always present, but it may just make the difference of reducing the cold drop from the roof.

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