damp proofing question

29 Nov 2008
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United Kingdom
Hi all, i have just completed a dpc on a wall in my house. i took the plaster off and injected the cream and left it for a week, the rising damp was pretty severe roughly about a foot and a hlf up the wall. When i put the base coat plaster on after the week i plastered over it 3 days later and wet patches are coming through! is this just a case of the trapped damp coming through and it should dry out? thanks for any advise Ian
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Did you have this properly looked at to determine the cause and the most appropriate solution? Or did you just do some self-diagnosis?

Have you used normal plaster?
Hi woody, i self diagnosed the rising damp from knowledge from my past homes. I used the new injection cream what is on the market and i heavely used it. I drilled holes in a line of bricks 40mm apart then the same in the mortar above and then i repeated this in the next course of bricks. I used from what i remember a light weight bonding base coat from bnq and to skim i used a multi finish plaster. It does seem as though the damp patches what are there are fading but i think that is due to me by drying them out with a blowtorch. When i dry the patches out they come back but not as severe so this is leading me to think it is just the water which is in the bricks that is coming through and drying out. Were i injected the cream for the first 2 courses there is only slight dampness in a few places but this is fading out like i described above. Do you think it is a case of the trapped water/damp coming through? Regards ian
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You will have to have a look at the specification for the cream you used for the injection to see if a drying time is recommended before covering with plaster. A sand/cement render or a specific plaster product may be required.

The only concern is whether the treatment was appropriate for the cause of dampness - ie was it rising under pressure, or was it penetrating (above the DPC level) or is some condensation occuring due to existing dampness and a cold wall. If this is a cavity wall with a blocked cavity, then the injection will not be effective.

Also did you treat the wall for any hygroscopic salts, which may give the appearance of persistant dampness

If the walls were soaked, then it may take several weeks to dry out, but a lot of this dampness should be heading outwards (if a solid wall). Persistant damp patches after 3-4 weeks would indicate a problem.
on the back of the tube it says cure time 4-6 weeks, so what does that mean to my wall drying out
.... probably 4-6 weeks before it starts to perform as it should?
I had a similar problem with Ultracure dpc cream and the damp is still there after about 9months. I think my holes were wider apart however.

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