wall insulation recommendations

[TackleItAll]

Hi, New here and this is my first post. Over the last almost year I have been renovating my first home. On the side of the house is a small extension that has a single skin brick wall half way up and then timber frame the rest until a tiled roof. There is no insulation and the room gets very hot and cold.
I ripped the old rotten tongue and groove cladding off the top half and put a breather membrane and feather edge cladding to the exterior. I am now wanting to insulate and plasterboard the inside to help stop the extremes in temperature. the space will be used for coats and shoes etc as well as somewhere for our cats.
The area isn't going to be here forever as I plan on knocking it down and extending the house at some point down the line but for now want something somewhat pleasant.

What is the best insulation to use on the walls? I have a stud wall effectively to put the insulation in which is 100mm deep to the membrane. the brickwork has nothing and just a single skin, do I line this to stop damp and put something on it, either straight plasterboard or insulate this?
The roof is also similar but I have some insulation roll left I can put in here and board over. the walls are my main concern and can't seem to find the best solution or insulation to use.

Thank you in advance.

 

[robinbanks]

50mm PIR against the brick, held in place with the stud wall, then fill between the studs. Personally I'd VCL over then board it

 

[TackleItAll]

I’ve added a picture to help show what I’m trying to do.

The studs don’t run all the way down the brickwork. I was thinking of painting the brickwork in black jack bitumen paint to stop damp then running some 1inch roofing batten all the way up from floor to ceiling to fix the plasterboard too and then using polystyrene insulation, 1inch on brick work and maybe 50mm in the stud work and then the 1 inch on top then covering with plaster board.

Would this be okay?

 

[DAZB]

I would go with 100mm PIR in between the studwork and fit 25mm treated laths full height vertically onto the studs which can be fixed also to the brickwork and then 25mm PIR between the laths to cover the brickwork and foil tape all the joints on the 25mm layer. You then have a fully taped, sealed insualtion layer and laths available to fix foil backed plasterboards to.

 

[TackleItAll]

I would go with 100mm PIR in between the studwork and fit 25mm treated laths full height vertically onto the studs which can be fixed also to the brickwork and then 25mm PIR between the laths to cover the brickwork and foil tape all the joints on the 25mm layer. You then have a fully taped, sealed insualtion layer and laths available to fix foil backed plasterboards to.

Thank you for your reply! What if I did this but instead of PIR I used polystyrene insulation instead? I just don’t want to spend the money on the PIR which will eventually be ripped out anyway.

 

[DAZB]

Polystyrene would do the job too and will still be noticably better than none at all.

 

[robinbanks]

I would go with ..

Don't forget, it's all being pulled down soon so I wouldn't make this iteration the forever job

I just don’t want to spend the money on the PIR which will eventually be ripped out anyway.

But if you're careful when you pull it down you can salvage the PIR for reuse, and likely stud work too. If you screw plasterboards up then don't skim they're also easy to recover