help insulating garage

mustbemoreorganised

hi, our house has been extended, a garage and two bedrooms were added. The bedrooms above the garage are freezing. As you walk down the corridor upstairs you can feel the temperature drop noticably. In the garage when I look up I can see the joists so I know i can put some insulation in. I've ruled out ordinary rock wool type as I think it will be a nightmare to hold up while I fix a board over it. I can see the foil covered boards that although are expensive look good. Has anyone fixed any of these, do I still have to put a board over them, or could I glue it in place. Finally, you can get the foil kind of insulation on a roll, looks quite thin, would there be any point in stapling some of this to the joists, would it make much difference. Any advice would be really welcome, thanks

savemoney

I am actually going to do this in our garage but doesn't have a room above

I got some cheap B&Q British Gas rockwool for £1 a roll and plan on using either plasterboard (need two people) or may use some woodern boarding, haven't decided which yet just waiting for warm day to do it as its cold in garage

You could use insulation board too, wicks sell it reasonable priced

27col

Ordinary fibre glass roof insulation in a roll would do.When I did my workshop many years ago I just stuffed the insulation in and it held there mostly by friction. If there was anywhere it was drooping I stapled some 2" wide tape to the underside of the joists and it kept it in place without any problems, until I boarded it. In fact string would keep it in place just as well. You get a ball of string and criss-cross the underside of the joists, stapling as you go.

maninthestreet

The alternative way is to use double sided tape to fix the insultation to the top of the (plaster?) board, then offer the board up to the joists.

savemoney

I was also planning on doing door as I dont use it much especially in Winter and it isnt a garage as such so would insulate that just for winter

Building a wooden frame around the door and then using some insulation boards probably fastened together with wooden sheeting

Plasterer

If your Joist are 400mm wide and your wool is 600mm wide cut it down to 500mm, when you push it between the rafters you will have 50mm each side too big. push it up and it will sit nice and snug - No tape - No screws - no extra labour

savemoney

The joists in my garage vary unfortunately and not that deep

Plasterer

savemoney wrote: »

The joists in my garage vary unfortunately and not that deep

Not a problem, 20mm each side then - joists gotta be deeper than 20mm
:beer:

savemoney

Would I have had problems with condensation if there is no gap between insulation and roof boarding

Space between joists around 35cm and depth 10.5cm plus a little bit for wood over beam to allow a slight slope

Plasterer

savemoney wrote: »

Would I have had problems with condensation if there is no gap between insulation and roof boarding

Space between joists around 35cm and depth 10.5cm plus a little bit for wood over beam to allow a slight slope

Sorry to sound like an !!!, as you only have 10.5 mm to play with cut it 20mm wider then (10mm each side ) and shove it up there - it will stay and have no inpact on your boarding. Where do you get 10mmm insulation from?

savemoney

Thanks for help

The rock wool I got was on offer for £1 a roll at B&Q back in Oct

Length is 4900mm
width 370mm
thickness 200mm