Hi
I'm hopeful of a little advice before I start a small diy project.
I'm converting my 25 year old detached brick garage into a 50% office 50% storage area by splitting it into two and plasterboarding half of it.

I've had a side door installed into it at the back

I'm stud partitioning with a frame, then insulation and membrane before platerboard.

However, there is some damp/little water coming in at the bottom corner of the garage, from next doors garden. I can see their land gies up to the dpc, where on my side I can see the dpc and my land is one brick below that.

It's just that one area that seems to leak.

My question us, should I tank that corner of the garage inside then put the really big membrane down and tape 1metre up each side of the Walls?

Happy to take my time and get this done over next 5 months.
Happy to post photos throughout project.

Kind regards. Thanks.

you could, or you could just remove the area of garden thats above your dpc?

_________________
http://www.peterborough-plasterer.co.uk/

Have dug a trench and back filled with stone, but still some water :(

did you tank the outside of the wall before you backfilled with stones? blackjack or similar?

_________________
http://www.peterborough-plasterer.co.uk/

No I didn't.

We've had a dry spell so the garage is dry now. I'll ask my neighbour if I can gain access to the garden again, remove the stone and paint the side with DPM paint (black jack or similar) and then replace stones once thats dried.

The plan, was then to paint the inside floor with DPM paint and up about 60cm from the floor. Once thats dried, lay a plastic membrane, and agin bring it up about 60cm and tape it to walls. Once all in place construct the timber frame (stud walls) - then insulate with kingspan or something like that, a vapour barrier, then plasterboard.

Sound ok? Any problems with liquid DPM then plastic, this ok to do?

I was slightly concerned about ventilation having read other posts about putting insulation against the walls, then a membrane then plasterboard. Would I need to install air bricks (this is more work, but if it really needs it, then I'll fit them)

kind regards

I've added some photos as this maybe useful to see what i'm aiming to do. thanks