Insulating Garage Wall - Connected to Bedroom

[Woggle]

Hello, we've recently had cavity wall insulation and loft insulation put into the property. However, we have one bedroom upstairs which is connected on one wall to the garage. The room is about 2-3 degrees colder than other rooms which we think is in part caused by the fact that the wall has no insulation on it (plus it's got more windows than other bedrooms).

I can get into the roof space of the garage to be able to insulate that part of the wall. But what is the best way to do it - timber frame and insulation with plasterboard (although it would be tricky to get the plasterboard into the garage roof space as it only has a smallish loft hatch)?
Thoughts welcome!

 

[kingandy2nd]

Stick some PIR board to the wall with suitable sticky expanding foam.You can cut the PIR to fit the loft hatch size. Also use the foam to fill the gaps/cuts in the PIR.

 

[motorbiking]

I'm imagining a double decker garage, but I'm guessing the garage has a pitched roof and it is this roof void that is adjacent to the bedroom?

Standard loft roll or rigid boards will be easiest and has fire proof properties. You can use roof battens to make a sort of "hey bale" basket to hold the roll in place or simply use some roof membrane.

held in place using wall board washers.