Damp patch on concrete floor

Dbo77

We've recently had an extension built and have noticed a damp patch on the concrete floor, spreading from the front external wall. The builder who did the job seems to think that the DPC membrane may have been punctured. He has used a product on the floor, K and A Tanking, and the damp patch does seem to have improved but we are still not sure that this will solve the problem. Should we insist that he dig up the existing floor and relay with new concrete? Any advice welcome!

wallbash

and the damp patch does seem to have improved

Over how long ?? Digging up a concrete floor without giving time for alternative's to work seems rash.

A concrete floor takes weeks to dry completely.

Dbo77

The floor was only laid about 6 weeks ago so I appreciate the concrete may not be totally dry. The problem is that the damp patch comes and goes, disappears when it's dry but comes back whenever we have any rain. We are just a bit concerned about what effect that will be having on the concrete and what's underneath ie insulation. We can't continue with the rest of the work until we've got a solution to this.