Damp Course

[Bigbray]

My building surveyor has told me there is rising damp in the front wall of my stone terrace.

I have had a couple of quotes for a damp course to be injected into the wall. My problem is one contractor said all the internal wall has to be replastered after the damp course has been injected. Another contractor has told me this doesn't need doing?

The internal wall doesn't feel damp so if I get the damp course done will the wall dry out without need for plastering or should I re-plaster anyway????

 

[breezer]

get more quotes from builders, injected camp course = waste of money for you.

I am not a builder, but i read these forums.

a damp coures is basically a sheet of plastic put on say 3rd or 4th layer up from ground of bricks, this is tp prevent damp being "absorbed by any bricks above the sheet of plastic.

so answer me this. how will injecting ANYTHING stop damp from rising?

you need to have the origonal damp course replaced, my neighbour *who is a builder) did his b4 we moved here, you can tell he had done it because you could see (at the time) the new line of mortar where he had taken the bricks out to put in new damp course

 

[oilman]

I got stung by this damp course rubbish. I was younger then and knew even less than I do now. Damp course injected and plaster ruined with a poor sand cement replacement inside. Didn't do anything for the damp. It was ventilation, or lack of it that was the problem.

Rising damp is so common (not) that Lewisham is/was offering a reward if you could show them a case. They still have the money. How did the surveyor determine it was rising damp?

 

[trowelhead]

I must say i agree with breezer about dpc injections.If you want to ensure a faultless dpc the only way to go is to install a physical barrier.It is unbeleivably messy,tiresome,time consuming and thankless but you will be glad you did it!
Buy a dpc the same thickness of your wall and chase out all the way through the wall (inside to out) but only for about 2 to 3 brick lengths then mortar in the dpc,continue this for the full length of the wall and then lap the dpc over when you get to the return.
Leave any internal plastering untill at least 2 months after replacing the dpc.It probably will require replacing if it is blown but otherwise dont worry about it,dry it out, prime with a stain sealer and redecorate!
I dont want to tar all damp firms with the same brush but they do tend to rely on the public worrying when they here the word DAMP!

 

[legs-akimbo]

Its a fact that most firms will tell you you will need a d.p.c. regardless of if you do or not, why not buy a cheap or hire a good quality damp metre that you stick into the plaster wall and take your own reading.
I would disagree and state that injection does work and if it fails you will be under guarantee (20 years) particually if you use the established and long trading companies... I have done loads of re plasters after d.p.c. injections and the fluid used DOES the job. Absolutely no need to take off all the wall just the bottom metre, so save yourself a packet and hack off the plaster yourself and organise your own plasterer, just get them to price for the injection, if you use any other than a reputable company you may well be sorry in the long term when your guarantee is not worth the paper its written on.

 

[breezer]

so tell me then how does it work? (i am not a builder)

I can not see how injecting anything into a hole in the wall will replace a deteriated sheet of plastic (dpc), to me all it does is fill the gap in the cavity.

Even if you drill holesat sy 6 inh centres you syill have the masonary there so the injected substance can not flow to make a "new sheet"

 

[legs-akimbo]

It is not intented to take the place of a propriety d.p.c. and is not injected into the cavity. A cavity construction is a relatively recent building practice and theese will incorporate the standard plastic d.p.c. or an enginerring brick d.p.c. (two courses)
The fluid is actually injected into the brick and cures within the brick leaving an unpeneterable barrier for the rising of damp, when done internally and externally it is a barrier that is guaranteed not to fail for at least twenty years. However there are so many firms that go bust and have bodged the worrk that you will have no recompense, that is why only long established companies should be considered because if in 2023 your d.p.c. fails they will be legally obliged as stated in contract to rectify the problem, believe me it works, for example when the injection is complete... and it stinks out the house for a couple of days b.t.w. when you flick water at the injected areas it acts just like the water running from the back of a duck is the best way I can describe it.

Regards

Robbo.

 

[breezer]

I didn't know that, thank you

 

[masona]

when you flick water at the injected areas it acts just like the water running from the back of a duck is the best way I can describe it.

What I don't understand is how does the dpc chemical treatment penetrate in the damp area to start with, surely the wall area must be dry first ?

 

[legs-akimbo]

There is pressure from the machine that pumps in the liquid... unfortunatley I can not tell you the scientific properties of this method ... may as well ask me just how an internal combustion engine operates ..I have not an idea other than it simply does