DPM on old car port base 5x4m

[Draughtsman]

I blocked up the old car port to convert it domestic use. It has a membrane under the conc slab but building control say I also need a dpm over the slab and slightly up each wall: makes sense I suppose, it'll have a plywood floor + engineered wood, on battens.

What type of membrane do I need?

There are a few slightly odd corners, and I will need stud/insulation on inside faces of some of the walls. It would be handy if I could get some membrane down around the outside of the room and joint a centre piece in later to preserve access for a while and prevent membrane damage during works, if some sort of jointing tape was available. How are joints created in DPM, are they rolled or taped joints?

I imagine that running the memrane up the wall in an inside corner would be easy enough to accommodate with a fold or two in the corner, but an external corner would need some sort of tape?

Do I need to protect the membrane with geotextile?

 

[Notch7]

My guess is that the original membrane sat underneath a concrete slab and there is not way to connect it to the walls.

I think that because generally dpm would not be required below a suspended floor.

Standard 1200 gauge plastic dpm is fine. If it is an awkward shape, a liquid dpm is an alternative.

You can join dpm, use a 600 lap mm and use tape. I think ideally it should be folded, but thats easier said than done with thick polythene so I just say a big overlap works.

You can buy tape for it. Or the super sticky gorilla tapes works. Dont use ordinary duct tape

 

[Draughtsman]

Not actually floating, I don't think I got that right: engineered wood on 18mm ply, on firrings or batten.

 

[foxhole]

Liquid Dpm .

 

[Draughtsman]

Maybe the void neneath the ply base will be enough to accommodate a folded joint.

I'll leave a meter or so out front of the baseplate, so I can do either.

 

[Draughtsman]

Liquid Dpm .

Sika Rapid 5 litres for £70 which conveniently doesn't seem to be a 2 pack, so maybe I could just do where the sole plates are going with that and finish the rest of the base later.

Coverage seems to ok with 5 litres providing 2 coats over 20m².

Has anyone ever used it?