20 Mar 2005
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United Kingdom
I'm new to this forum, so hello to all. Glad to see such a wide range of opinions and healthy debate on a subject that is P*****G me off.

I, like madsey, have exactly the same problem. 1900+ mid terrace with front and back cavity walls, and single brick dividing walls with my neighbours.

The house has had chemical damp proof treatment, before I moved in. I think it was about 7-8 years ago. Alot of it seems to have worked admirably. I am renovating the downstairs now (having finished most of the upstairs) and upon removing the skirting boards, the bricks are damp in some locations. There does not appear to be a dpc, although in some areas there is a very fine black crumbly line (bitumen perhaps ?) The floor is solid, i.e. onto earth I think, and at some stage in the past, perhaps when the chemical injection took place, it has been bitumened (quite thick and effective).

The particular problem I have is with the front corner of the house (I am suspicious about the fact that it is worst where a flower bed abuts the front wall one the house). The level of the soil is not higher than the chemical dpc applied, it just looks as though the chemical dpc has failed for some reason, or not been applied correctly (these bricks are damp the whole way through !)

So to my questions :-

1. Should the chemical dpc fail, and if so why is this ?

2. I have ordered some of the safeguard dryzone product (before reading this forum actually), does anyone have any tips on using this product ? Do I try and dry the bricks out as for a silicone injected dpc, or leave them damp for the 'cream' !?! to disperse more efectively as is implied in the literature ?

3. I have noted the points raised on ventilation and other methods to reduce damp in houses, and will implement these accordingly. What is the best building material to cover the bricks I hope to re-treat with this dryzone stuff ? Should I go for a sand/cement render with plenty of rendamix (is that the right stuff as well ?) or perhaps I should look into the lime plaster idea ?

4. What happens to the foundations below the dpc ?? Chemical or otherwise ?? This must happen on all houses, are all bricks so damp below a dpc (chemical or physical) and if so do they not deteriorate over time by being damp esp. the mortar between them ?!

Seems like a contentious topic this !! so I am a bit nervous of starting it all off again, but I got a problem and any/all advice is welcome.



psot has been split
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Chemical Damp-proofing has not got a good reputation.

I am not sure if it is allowed to recommend another site on this forum, but, I think you would find some interesting information on the Daily Telegraph site, if you log in to that, and do a search for Jeff Howell, his column is called 'On the level', and he has made some caustic comments on the subject.
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most injected chemical dpc is at best patchy and at worst a total rip off.

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