Bridging damp proof courses

3 Jun 2003
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United Kingdom
A month ago we had a chemical injection damp proof course. This involved the skirting boards being removed, holes drills between the bricks, and a special chemical being injected into the walls. The existing render was also removed.

In the last few days a plasterer with 40 years of experience has re-rendered the walls, but to my surprise has rendered down to the ground such that the render covered the brick above and below where the damp proof course was injected.

I mentioned to him that I understood that this would mean that the render would allow rising damp to continue up the wall via the new render, and he says that because he has added a water retardant to the render that there shouldn't be any problem.

Since we will be putting back skirting board, I can't see any reason why the wall needs to be rendered down to the floor, and for safety's sake I am considering asking my experienced plasterer to hack off the bottom 6 inches of the render.

I don't want to annoy my plasterer especially as he has so much more experience than me, but unless he avoids "bridging the damp proof course", my warranty for the damp proof course will be invalidated (or may already be!).

Can anyone comment if there is any risk due to rendering the wall to the floor? Thanks!
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What I don't understand is the floor level should be above DPC. Do you have floor screed or timber joists floor? Are you saying the rendering is below the flooring?
Your Damp Proof Course should not be as high as the skirting boards because by the time the damp has got that high it is already over your floor level and will then transfer damp to your floor covering (carpet,laminate etc). The Damp Proof Course should be usually 2 course of bricks above your external ground level and should be drilled into the brick itself and not the mortar. As you know each and every property is different and your ground conditions may have determined the height of the injected DPC but if you can post a clearer picture of your situation we can probably help further.
how can i tell if they drilled and pumped my walls when i had this work done also.when had house surveyed before i bought it surveyer said that there was damp,along certain walls and needed a survey from damp firm.
survey came back,needed to hack off plaster above certain level drill and inject replaster etc has been done over two years now,i have also an isurance backed guarantee.
having lived in the house i have since learned that above where damp was very bad is a bathroom,water has gone down the back of plaster and caused this damp and over the years salt had appeared,wall was covered with ply board/pine t&g so surveyer could not get good look at all walls
my house is 100 year old terrace,so what i want to know if there was any damp,have i been ripped off by damp company,as i understand they should drill and inject both exterior and interior walls,but there is no evidence of drilling outside,my partner was here at the time as i was in work and she says that she was not really taking any notice.i am none the wiser but i think that i have been conned and have had a lot of plastering work done for nothing and at a great deal of cost.
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Sadly a lot a people do get conned regarding damp walls problems.The most common problems are called what is known as ' trap condensation ' (where there is not enough air flow around the room) then they tell you it's broken DPC ! They are going to find faults with your property to keep their business floating and I've been told my 25 years warranty is not worth the paper it written on.(Sound about right).
Too true. I was witness to one firm who used to drill into the mortar joint until they hit the cavity and then inject the fluid but all this was doing was pumping the fluid down the cavity ! It should be injected into the brick under pressure until the brick actually starts to 'weep' and is then saturated with fluid and of course with the whole course of bricks being done then this creates a treated barrier against damp. Obviously certain types of bricks won't 'weep' such as Glazed face bricks etc, but experience and practice tells you how much time and fluid it takes to permeate the brick fully. Sadly a lot of untrained jobbing builders have jumped on the Damp Proofing Bandwagon by hiring the equipment for the day and charging the customer a fortune for a job without having the proper training. Like the previous post said , the 25 year warranty is about as much use as a chocolate fireguard. It will pay to check any Builders credentials if they offer Damp proofing and if they can't back it up with the right paperwork then find one who can. A properly trained installer will be happy to oblige because they won't want the cowboys tarnishing their trade. A long winded post I know but I hope it helps someone out there.

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