Filling the gap between concrete floor with no dpm and wall

30 May 2014
Reaction score
United Kingdom
Concrete ground floor. No DPM. Cavity wall with bitumen dpc. Screed with ceramic tiles laid on it. House built in 60's. The screed touches the wall above dpc in many places. Please take a look in the album:
where I uploaded a few photographs and a diagram of the situation.

I'm concerned about the screed touching the wall above dpc, because there is no DPM installed in the floor and the moisture can freely travel through the channel created by the screed touching the wall. I don't really know how moisture resistant the screed is. It's the original old screed from when the house was built (60's).
I took a few readings of moisture content using a simple moisture reader (I am aware one should treat those readings with a pinch of salt, but that's the best I have at the moment) and it seems there is no problem with rising damp (the moisture content is indeed higher in the first block above dpc, but the reader says it's not more than 3% and the moisture reading in the next blocks above it is around 1%.

I'm renovating the room and plan to install internal wall insulation. This will require creating a vapour barrier so I would like to eliminate any potential problems with the floor moisture entering the walls. At this stage I'm not prepared (financially and "morally") to replace the floor (installing DPM) as this is major operation (would need to be on the whole floor, not just one room). I guess the ceramic tiles act as sort of a DPM (I guess I could make a bit sounder by sealing the grout). I would also like to put timber flooring in the room on top of the ceramic tiles.

Would you have any advice regarding what can be done in this situation?
I was thinking about removing the screed touching the wall above dpc (say 1'' into the room) and fill it with some waterproof tanking slurry, maybe also using a liquid dpm locally above dpc where the screed touches the wall (before using the tanking slurry).
Do you think it's sensible?

I would appreciate your help and advice.
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