I had an extension built 25years ago and have had trouble with mold and dampness in one corner, i called in some builders who using a meter said I had rising damp. The old floor was dug out and they appeared to show me that the membrane had not been up to the level of the wall damp proof course. they dug down to the old membrane and placed a vertical membranedown below the old one and upto the Skirting board level and then laid a further membrane down and replaced the foor with concrete.
In order to hasten the drying process I used a combination of a Dehumidier and fresh air.
I waited some three months before doing any thing then as a belt and braces idea I coated this with Aquaseal two coats, to my dismay this would not dry beyond the sticky ,and i confirmed that this would be a problem with the makers.
To sort out this it was suggested that a coat of self levelling concretewould sort it out and this was done Four days later I had the carpets fitted and thought all was well.
my wife today indicated to me that the room corner was very cold so i have taken up the carpet and sure enough the dampness has returned.
If it is not rising damp can it be possible that the cavity wall is bunged up,but regarding this no damp readings are showing on any wall
Any Advice you can offer would be appreciated