fireplace damp

I've just finished and partially decorated a fireplace to house a log burner.

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you can see it appears I haven't solved the minor damp problem. The constructional hearth is entirely replaced and encorporates a DPC. The house is 2 leaf brick construction 1930's with bitumen DPC on the inner leaf. ? on the outer leaf but with 2 blue brick courses on both leaves. There is no damp problem any where else in the house and never has been whilst I've been there. The patches in the picture do seem to be damp when tested with multimeter. The plaster was allowed to dry fully by eye ie to the light pink colour, there was no sign of damp at this stage the lower wall did not seem to dry much slower than the rest. How long does it take for the original damp to dry out. There was exposed brick and the constructional hearth was completed for the last 4 months.

Can I drill & inject as low as possible some form of silicone to the inner leaf - I believe this is a technique.

-- Mike W

Reply to
visionset
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The damp should have dried up by now, hence you've still got water ingress somewhere, it this an external wall?

Your problem could simply be that you've no cowl on your chimney hence water is coming down the chimney and somehow finding its way into that area - you may find that it clears up once you've had your log burner going for a few weeks by drying out the chimney

Jon

Reply to
Jonathan Pearson

Yes external wall. If it was coming down the chimey it would affect the upper part, not the lower. This smacks of rising damp to me. And like I say it was a problem before (with cowled flue), but I thought I'd solved it with the DPC in the constructional hearth.

Reply to
visionset

I'd do a quick test for condensation. Just lean a tile against the damp bit and see if the face gets damp

Reply to
Stuart Noble

My guess is that at some stage your house has been injection treated. A fire was in the fireplace and so they didn't treat that area. In my opinion you have 3 options.

  1. Inject as you suggest
  2. Strip old plaster back to brick in affected area up to 3ft and then re render using a water proofer and ensure that washed sharp sand is used rather than soft building sand, and that a strong mix is used. Then plaster on top.
  3. Do both of the above.

In my experience most rising damp problems can be solved by step 2. In fact if injection is carried out and then the wrong render mix then you still usually get damp... what does that say about injection dpc's? But whilst old is stripped off a bit of injecting would do no harm... so long as chimney is also cavity construction. My guess is that it'll be solid brick.

If it were condensation then you would eventually expect to get black mould forming.

Hope it goes well. Calum Sabey NewArk Traditional Kitchens 01556 690544

Reply to
calums

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