Injection damp proofing: does it ever work?

[silly_savage]

I have a Victorian end terrace that has been a bit neglected over the years, that's not to say not modernised, but done so unsympathetically. The main living space at ground floor has a concrete floor which extends from side to side of the original house through the hallway. The rear of the house is also a concrete floor, but this is done to modern standards with (most of) the walls there also being modern (block cavity walls). The walls at the front are your usual Victorian red brick & lime mortar

The issue I have is on the central walls of the house which are showing signs of rising damp. We have humidity under control for the most part, and it's very localised to the central most walls up to about 1m high, so what I believe is happening is the non-porous slab is forcing ground moisture up through the more porous walls. It may have also breached the original DCP of the walls or simply wicking moisture up where the wall and the floor meet. I do wish to renovate the room at some point but I'm slightly lost as to how to tackle this issue

The way I see it is I have two options:

i) dig out the concrete floor and reinstate a timber one as it would have originally been (+ insulation)

ii) Injection DPC just above the slab & re-plaster

Without getting any quotes, the latter seems like it would be the most cost effective (a concern as I don't want to plough endless amounts of money in to this house as I'm not sure how long we'll be here), but I worry about whether it will actually work. I've read a lot about rising damp being a myth, which I'm sure is probably true if you have a correctly functioning under-floor cavity, but we definitely have it here. By the same measure I don't want to spend a load on damp proofing materials and re-plastering only to have the problem return 6 months later.

• Has anyone has/done injection DPC with any success?
• Can it be successfully DIY'd? (It seems there's a few products for this these days)
• Is it as much work/cost as it sounds to remove a concrete floor and replace with a suspended timber one?
• Is 'tanking' sand & cement necessary in place of conventional gypsum plaster after injection DPC, as so many of the specialist companies seem to love doing?

Thanks

 

[John D v2.0]

Yes
Yes, i used the one from Wickes it was about 25 quid a tube, on a single brick internal wall
Yes, lots of heavy work but not technical.
Yes, as gypsum and water don't mix well

And don't pay too much attention to the extreme opinions of rising damp. Yes it exists but no it's not the only cause of damp. And chemical damp proof course is not always the best fix.

 

[^woody^]

Injection can be a successful remedy for a correctly diagnosed problem of rising damp due to low pressure capillary action. If the cause is something else, then injection may not be effective.

 

[bobasd]

OP,
using the search button, why not read up on some of the threads that deal with your question in one way or another?
you may not get complete answers but you will see whats been done or suggested regarding DPC injections of various kinds.
and perhaps just as important you will see other, non-injection, possibilities for dealing with rising damp.

your concern seems to be with getting advice for dealing with actual damp conditions - so its best to post pics of these conditions.

 

[silly_savage]

Thanks @bobasd and others for your opinions, so I've taken your advice, and the usual remedy seems to be tanking to above the DPC then plaster over. I'll talk to my plasterer mate and see if he's familiar with the process.

I would love to have a nice suspended wooden floor and then lime plaster the whole place in keeping with it's age, but that'll be £££ we won't ever see back.