Damp in floor

[bathtub tom]

I've bought this bungalow, built 1960. A laminate floor laid in the hallway has distorted, the company say the floor is damp. A test with a hygrometer sealed to the floor measured 90% RH. The water meter (measures down to 0.1L) doesn't move when observed for over an hour. The bargeboards, soffits and gutter have all been replaced last year. The combi boiler hasn't lost any pressure since being serviced last year. The drains are outside the property walls. There's no water dripping from the ceiling. There's no visible evidence of damp.

I've read from an adhesive manufacturer: "Floor slabs that are pre 1965 are unlikely to contain an effective damp proof membrane". Is anyone able to shed more light on this statement please?

 

[bathtub tom]

It looks like I've found an answer to this myself:

Building regulations introduced in 1965 make it a legal requirement to install a structural damp proof membrane in new buildings.

Maybe this could help anyone else.