Insulating a single skin garage

Discussion in 'Builders' Talk' started by ibanezman, Feb 10, 2014.

  1. ibanezman

    ibanezman Member

    I don't put my car in the garage, so I'm thinking of splitting it 1/3 and 2/3, into a room where the door continues to open as usual (1/3), studding across and then having a man/games/music room in the other part (2/3).

    So, creating the 1/3 is easy. It's insulating the 2/3 which I'm not 100% sure about...

    Plan A is to:
    • Divide the garage into two parts with a stud wall, insulated with fibreglass or sheets and instead of plasterboard, use a reasonably heavy plywood in order to make it a bit more sturdy when it comes to putting hooks/nails etc in to hang tools and other stuff.
    • Line the remaining half, using batons at 600mm spacings all round the room, again insulating with fibreglass or sheets.
    • It has a pitched roof, so create a 'ceiling' and insulate that too, using fibreglass.
    What I'm not sure about is how to insulate the floor, will carpet and underlay be enough? What's best to create a ceiling, plasterboard or thinnest plywood? What's best to line the walls, plywood or plasterboard?

    If I use plasterboard it won't be plastered. I'm not trying to create the warmest room ever, just a space which will be heated as and when I want to use it, and be pleasant enough to use in the winter without trying desperately to heat a room which will lose heat faster than I can generate it!
     
  2. Phil the Paver

    Phil the Paver Screwfix Select

    Is this a free standing garage or integral garage.
     
  3. ibanezman

    ibanezman Member

    It's freestanding.
     
  4. Phil the Paver

    Phil the Paver Screwfix Select

    FatHands likes this.
  5. ibanezman

    ibanezman Member

    Ok, that's fine, thank you. Just curious about potentially using plywood over Celotex/fibreglass as it would be different in terms of breathability compared to plasterboard and skim.
     
  6. Phil the Paver

    Phil the Paver Screwfix Select

    It shouldn't make any difference if you put the breathable membrane on the stud work as in link above, as you have said it will be better for fixing things too.
     
  7. ibanezman

    ibanezman Member

    Ok, great, thank you. I can folow the same guidance for the floor then by the sound of it, but obviously use something (chipboard?) suitable for flooring over the battens and insulation material.
     
  8. Ib, if your floor is dead flat, I think you could just lay down rigid sheet insulation (Celotex/ Kingspan) and then 'float' your chipboard flooring over it (glued at the joins). But get confirmation on here first. (After having laid a DPM over the whole garage floor and a bit up t'walls first).

    But, in case it might have movement, you almost certainly would be better off by screwing some treated battens down to act as joists first, and then pack in between them with insulation. Add a further thin layer over the whole lot if you can afford the headroom, and then screw down the chipboard sheets.

    Although it is definitely worth doing, the floor insulation is the 'least' important. As my attached garage floor slopes considerably, I ended up using battens varying from 130mm to just 25mm as joists, so the Jablite (the most pitiful of insulation materials!) I stuffed in between is only that thickness too. All covered in T&G pine floorboards. It is very cosy tho' - no issue of a cold floor at all.
     
  9. plane-it

    plane-it Member

    Jablite is actually better than the denser extruded stuff in one respect that it doesn't out-gas over the years and retains its rating due to the individually sealed bubbles that result from the expanded rather than extruded manufacture.
     
  10. ibanezman

    ibanezman Member

    The floor is pretty much dead flat, but there is plenty of room to build up by 2-3 inches to accommodate battens etc. Just wondering though, it's a poured concrete floor which presumably has DPM in it - should I therefore put another DPM on top of the concrete?
     
  11. Phil the Paver

    Phil the Paver Screwfix Select

    Yes definitely, the odds of a garage having a DPM are nil.
     
  12. Phil the Paver

    Phil the Paver Screwfix Select


    Yes the odds of a garage having a DPM are NEXT TO NIL. :) :) :)
     
  13. ibanezman

    ibanezman Member

    In that case, the chances of me not putting down my own DPM are next to nil...
     
  14. In which the chances of you not knowingly forgetting to not place a DPM is, um, is... :confused:
     
  15. ibanezman

    ibanezman Member

    Somewhere approaching a triple negative?!
     
  16. Phil the Paver

    Phil the Paver Screwfix Select

    Right, just incase, DON'T forget the DPM. :p
     
  17. Wouldn't we laugh if his Ibanezes ended up with damp bottoms a year hence.

    I mean, it would be terrible if... :oops:
     
  18. John Manlow

    John Manlow New Member

    Sorry to hijack your thread,
    Ive got a similar project, double garage with single doors (convert into windows, bu my question is what comes first insulate the floor then the walls then the ceiling or walls first etc etc, I know how to do it just not sure of the correct order, and yes I am putting a DPM in, double skin walls no ceiling a yet. Knowledge gratefully accepted.
     

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