Waterproof membrane

[Pocster]

Hey all

 

Got this sussed for the walls and floors on my underground hobbit dwelling. Internal channel to take water to sump.

 

Although I intend to have a waterproof roof I still worry about water ingress via the concrete ceiling (parking above it).

All examples I see of placing the membrane on ceilings are in nice curved ceiling basements! ; mine of course is square!

I can't just attempt to fix "as is" because I'm worried about sagging and hence leaks if any water did get in.

 

Any other methods to "water drain" my ceiling???

[Pocster]

It's been suggested I make a vaulted ceiling !

 

no good doing this in wood and it's been suggested not that easy .

have to somehow get the dimpled membrane over it and linked into the wall membrane!!