Tanking Slurry gone wrong? What next?

29 Dec 2023
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United Kingdom
Hi, new here.
I have a single brick garage with truss roof at the end of my garden which I use for storage and has some condensation problems as cardboard boxes and plastic storage boxes were showing signs of damp.
When there is heavy rain, small puddles would build up in the perimeter of the floor. One of the issues was that the previous owner of the house had put some decking higher than the damp course which ran along the garage.

I got some damp proof builders to look at this and they recommended applying a tanking slurry along the perimeter, floor and a few bricks up the wall.

It has now been a couple of weeks since they applied the tanking slurry (Vandex BB75), but I am still getting some patches, which are damp to touch. I was told that it usually takes a day or two to dry, so its been way more than that..

Has the tanking slurry failed? or otherwise where is this dampness coming from?

I plan to lay a floating floor (DPM, insulation board, then chipboard) on the floor to help with "insulating" to prevent the condensation.

Question is should I...
> Just lay straight over this as is?
> Could I apply a liquid DPM over the tanking slurry to form another barrier (and then apply the floating floor)?
> Wait a bit longer to see if this dries given that it is winter? (garage door has a small gap below to ventilate, but otherwise it is shut at all times)
> Or any other suggestions?


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