Internal garage partition help

24 Jan 2023
Reaction score
United Kingdom
Hi guys,

I have had a look through the threads but i can't seem to find definitive answers to what i'm planning on doing, so thought it maybe best to put my questions out there, and hopefully you guys are able to help. I've trawled through google, youtube, etc, and each time- it seems like something else pops up that i am going to need/should use/etc.

Anyhows, at current:-
My house is a year old, I have an internal double garage, measuring 6500mm in depth, and 6000mm width, with a height of 2800mm. The rear wall has a fire door going in to my utility room which is 900mm width, and 700mm from the left wall (looking 'in' to the garage). The left side wall is thermalite internal, and brick external. The right side wall is thermalite, on the other side is my hallway. The rear wall (with the utility door) is plastered, painted, and 'finished', the left and right wall are brick. The ceiling is plastered and finished, and the floor is a concrete slab (set down from main house too, step at utility door).

My proposal:-
Fairly simple, i propose to put up a stud wall from left to right, 2500mm from the rear wall, leaving 4000mm for my garage. So the proposed partition will create a 2500x6000 room, and a 4000x6000 garage. The room will incorporate a door (non-fire proof- guessing as it's still essentially the garage- this is not needed?). The door will be the same measurements as the utility door (so 700mm from the left wall).

The room will then be used as a little home gym on one side (treadmill/tv/dumbbells/etc), and just general storage on the other side, which also incorporates the boiler. The room won't be a 'lived in' room, it's just technically to split the garage, make a bit of a gym, and extra storage for the house.

My plans:-
So my plan for this is to use 3000mm 3x2 cls for the stud wall, with 400mm centres, 1200mm high noggins repeated twice. I was thinking 12.5mm tapered edge plasterboard 1200x2400, and skim the joins, as opposed to plastering the whole room- then paint. For insulation i was going to use 50mm polystyrene (Like this). General door casing with a standard internal door.

For the 'internal of room' left and right walls, i was going to batten them with the same cls, same insulation, and same plasterboard.

For the flooring i was going to use some kind of rubber tiling (Similar to this), with maybe laminate or something on the 'storage' section of the room.

My questions:-

Q1. Is 3x2 CLS ok for this? Including the battening? Whats the best way to screw down in to the concrete slab? (UK based)
Q2. Underneath my CLS, and the battens touching the brick walls, should i use a roll of dpm underneath them? (Like this)
Q2. Does the plasterboard need to be installed 'staggered' or just lined up squarely?
Q3. Is the insulation choice ok? The room doesn't need to be warm as such, just protected from the elements
Q4. Can i vent a portable air con unit through the wall in to the 'new' garage space?
Q5. Is a standard internal door ok for this?
Q6. Should i use 3x2 to batten the side walls?
Q7. Should i use the same insulation for the side walls?
Q8. Do the side walls need some type of vapor layer? (i believe this goes between the plasterboard and the insulation?)
Q9. Do i need any type of dpm/vapor layer on the garage facing side of the stud wall?
Q10. Do i need to do anything with the floor, or can flooring be laid on to the concrete slab? (dpm sheets below, maybe?)

I probably have a thousand and one questions, but these are the main ones that i can't seem to get answers to for my specific project, so when/if i think of anything else i will be sure to raise the question.

And finally, i'm a handy diy-er so i have no doubt i can make this thing look half decent (hopefully), i seem to be able to do most things 'inside', but when things start becoming exposed to the outside world, that's about where my knowledge ends! I'm probably way over complicating this too, but i'd rather get it right, than get it wrong and have to re-do the whole thing!

Any advice is more than welcome, and any answers to any of my questions will be greatly appreciated. I can provide some diagrams if needs be, i just wanted to get this post up sooner rather than later as i'd like to make a start as soon as possible.

Thank you, and i hope to be a valued member of these forums :).

PS. I hope i've posted this in the correct place!

Last edited:
Sponsored Links

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local