Lack of Damp Proof Course in old wall.

[Rick Random]

I have just removed an internal single skin brick wall in my c1900 house (and put an RSJ in). The two rooms had concrete floors put in, I believe about 15 years ago, with damp proof membranes which went up the old wall a little way. There was no damp prooof course in the old wall. The lowest bricks in the old wall were a bit damp, but didn't seem bad to my untrained eye. The top of the remaining bricks are about 75mm below the floor level.

My question is how should I deal with the lack of DPC/DPM in what is to be a floor, but was a wall. I am thinking in terms of avodiing future damp problems and keeping the building inspector happy. Should I:

1. Fold the edges of the membranes onto each other (they meet in some places) and put a DPC over them, then sand and cement over to the floor level?

2. As 1 but with a strip of membrane instead of a DPC?

3. Just fold the edges of the membranes onto each other then sand and cement over to the floor level, but no DPC/more membrane and don't worry about any gaps?

4. Some sort of waterproof sand and cement and additive, if there is such stuff?

5. Something else?

Any advice gratefully received.

 

[NT]

Since you're talking about modern building technology you might get a greater number of respondents on news:uk.d-i-y

NT

 

[Gervase]

Not that it's particularly relevant to period properties, but if you want to join two plastic membranes, most building inspectors will insist on a one-metre overlap (1.5 metres, with joins double-taped if you live in a high-radon area) although many will sign off a 600mm overlap if they're in a good mood.
Thus it doesn't sound as though you've enough spare material to satisfy the inspector in this instance.
The bigger picture is that you will have to put in some sort of DPC because concrete floors and membranes are notorious for forcing ground moisure up the walls. Sadly, that's one area where building inspectors and those with a passion for period property will always differ.

 

[Paul Hopper]

Rick

You could try hot poured mastic asphalt provided the floor base is sound and more or less level. you should find details in Yellow Pages etc.,

As for the wall, those of us with the older and period properties have a deep suspicion of provision of damp proof courses, especial those of the Chemical type. As a surveyor myself, with some small interest in the subject (personal not professional!) I prefer where possible to insert a blue brick dpc or an astos type membrane. With Chemical dpcs they are only as good as the installer. ie: choose a recommended installer, avoid the man and van type if you can. Discuss the matter with your building inspector, he is supposed to be your friend.

Paul