Extension insulation

[Sammyf27]

Good evening
I am planning on insulating my single brick extension, it is a 1970s house with a side extension that is single brick it has a shower room one side a utility on the other and a hallway with a external door, it has a step down from the main house and a concrete floor.
im planning on putting studwork and insulation on the walls and ceiling also raising the floor now my questions are

do I need to put a vapour barrier in ?

do I need any ventilation as I have a shower in there I do have an extractor fan but dont think it’s powerful enough

raising the floor is it worth insulating this aswell and the best way to do this to match the rest of the house

 

[motorbiking]

Some photos would help, is this some sort of "orangery" type extension? You don't need stud work for the insulation, you can dot and dab (or plasterboard foam it directly on to the brick). Celotex and other brands have a foil vapour barrier built in. Studs just add cost and increase cutting, while reducing efficiency. The floor will benefit from insulation. Here I would consider joists at 600 with celotex between and T&G top.

50mm on the floor and 50+ on the wall/roof will make a big difference. Obviously to make it Building Control compliant is a different question.

 

[Sammyf27]

so this is the floor plan the red outline is where I will be insulating but unsure of the green outline as it backs on to a storage type bit, been reading a lot about the vapour barriers as have alot of condensation in there from the shower even when the extractor is on , would it have a negative effect if I did install one aswell or just a waste of time and cost?

 

[motorbiking]

Are you tiling over the insulated wall after? The vapour barrier stops moisture from coming through the brick from outside. The moisture you refer to is caused by hot humid air condensing on to the cold poorly insulated wall. With the PIR in place this wont happen. If you are concerned you could use a waterproof tile backer board on top or instead of plaster board.