Insulation board, is it worth it?

[danoid]

My garage is attached to my house, so you'd open the garage door then at the end is another door and you're in the kitchen.

Between the garage and kitchen is a stud wall, it does have wool insulation which is approx 100mm.

If I was to replace this with insulation board, is it really worth the effort? Heat does leave the largish kitchen diner pretty quickly, and I know how cold the garage gets so wondering if some heat does leak there and whether insulation boards is worth a try.

I've tried looking at resistence values and quite frankly I'm a bit confused, but it does look like 100mm of insulation board is at least twice as efficient as wool.

If it is worth it, then I might as well get a few more boards and place them on the garage wall (internal facing) next to where my downstairs toilet is, as the heat really goes from there, and I suspect it's just leaking out into the garage (plasterboard then aerated block)- it doesn't help there's a mini loft above the toilet either. What's the best way for me to stick the boards to the garage wall, i'm guessing some adhesive?

Thanks

 

[danoid]

I've added some pictures to make it a bit clearer, so the picture with the door unscrew the plasterboard (it was never plastered) remove wool insulation and put insulation board (if it's worth it)

The other picture showing the wall where the shower is, stick on insulation board

 

[oldbutnotdead]

You're correct that properly fitted PIR board is about twice as effective per metre thickness at containing heat. That construction (stud wall separating kitchen and garage) sounds very iffy, as does single skin blockwork between shower and garage.
Advantage with wool is it's easier to get a draught proof install...
I'd suggest leaving the wool in the wall, remove PB, fix 50mm or greater PIR to the studs (not between them) then reboard. You can get really long plasterboard screws...
PIR to the blockwork- non-solvent Gripfill or board adhesive works fine

 

[Tigercubrider]

Is that a firedoor? It should be
It doesn't look liked a very good fit.

 

[danoid]

Is that a firedoor? It should be
It doesn't look liked a very good fit.

The door is, but impossible to use the garage as a garage anyway so not concerned

 

[danoid]

You're correct that properly fitted PIR board is about twice as effective per metre thickness at containing heat. That construction (stud wall separating kitchen and garage) sounds very iffy, as does single skin blockwork between shower and garage.
Advantage with wool is it's easier to get a draught proof install...
I'd suggest leaving the wool in the wall, remove PB, fix 50mm or greater PIR to the studs (not between them) then reboard. You can get really long plasterboard screws...
PIR to the blockwork- non-solvent Gripfill or board adhesive works fine

The wall where you see the shower on the other side is the downstairs toilet so nothing iffy about that as it was built like that with all the other houses back in 2000 or so.

If you look at the house from the front it’s garage | wc window | front door | lounge