Damp Proof Membrane & Stud Walls

[KingRolo]

I recently posted a message regarding our garage conversion and hope people can help with the next set of problems!
Building control have visited for a retrospective certificate and it appears the builder did not conform to building regs on 4 points.
The major point being no waterproof membrane under the metal studwork that sits directly onto the concrete garage floor, the bottom/sole plate. The issue being the plasterboard sits directly on the concrete, so can absorb moisture.
What options do we have that would satisfy building control? Could we remove x mil from the bottom of the plasterboard? I can't see how plastic membrane can be retro fitted without huge cost/time.
Thanks

[The Builder]

This is going to depend on your Inspector. A rookie would simply consult the book, and throw gospel at it... insisting on full retrospective works.

One who, by experience, might be more pragmatic. It's easy to protect the plasterboard. Just take off the lower part of the board (say about 600mm), then run a membrane up the studwork, with 150mm or so turned along the floor. link this to whatever damp-proofing you intend to use on the floor.
Replace the board.

With timber studs, protection would be needed. I guess it could be argued that galvanised metal framing doesn't need so much protection.
Breaking the rules, of course, but he may go with it in this case.

I'll have a good think about alternatives.

[The Builder]

Second thoughts ............ 600mm may be over the top. 300mm should do.