Dot and Dab on tanked wall problem

[several]

Recently renovated an old house, stripped double skin(no cavity walls) to brick and applied 2 coats of tanking slurry before dotting and dabbing plasterboard.

Got some damp patches appear in certain isolated spots, they just look like the paint is wet. All the patches are on internal walls.

I have no idea how to fix this issue without removing all the plasterboard and seeing what's going on but we have skirting/carpets down so that's going to be a nightmare.

 

[freddiemercurystwin]

How long ago did you paint/plaster?

 

[freddiemercurystwin]

This is IMO the huge risk with using renders as tanking, they are not fool proof.

 

[several]

This is the first time I've used it. Previously we've always used tanking membranes and stud walls. I was always a little cautious of it as well but knew someone who used it on a full job and that was fine a year later.

This job of mine, was completed May 2014, so it's been a long while. Some of the damp patches are around the edges of where the dabs are which seems odd, I would have expected them to be on the dabs.