Is damp usually condensation?

[mrrusty]

....and after 440 pages of theory, the writer of the Salford report carried out a real-world experiment and wrote in his conclusion "If I am critical, however, I do recognise the limitations of this study: it was, after all restricted to a single house of a particular type and occupation"

What happens in one properly can be different to another.

and THAT is the truth of it!!! and why there is such controversy. I'll stick to my own theories and remedies which have worked well in my own 1902 house, and they don't include "damp" treatments.

 

[stuart45]

Damp treatments are another story. The first question is whether rising damp can happen. Even Jeff Howell has changed his advice, saying that if it's rising damp there must be evidence of salts.
The correct remedial work is often remastering with lime.
Your home of 1902, probably would have had a DPC.

 

[mrrusty]

Your home of 1902, probably would have had a DPC.

It does, and a cavity, but when we inherited it, the internal walls were so wet you could almost literally wring water out of the plaster. The remedies have not included lime plaster......we could start another discussion about using that in sealed houses with DG, blocked up flues etc....and why IMHO it probably isn't a good remedy in many (but not all) situations....

 

[stuart45]

I've worked with lime for over 30 years now, although as a bricklayer, the plasterers did the inside work. I'm not aware of any issues using a lime plaster in an old property, apart from the fact that lime pointing and plaster aren't a miracle cure for all damp issues. What was the issue with your house?

 

[mrrusty]

What was the issue with your house?

An old man living basically in one room and 115 years of coal fires every day.

I think when considering breathable lime plaster you need to consider whether you are trying to allow the wall to "breathe" in to the room, or the room air to "breathe" through in to the wall......

 

[stuart45]

Air usually goes both ways through a wall, but with a cavity wall it will normally condense on the inside of the outer skin. If your inner walls were full of salts, then condensation would be the main issue, so maybe you drylined the walls?

 

[mrrusty]

yes, exactly. I had a conversation with my BC man once we'd stripped back to bare brick, and our consensus was internally insulate using insulated PB incorporating a VCL to create as near an air-tight barrier as possible, and then rely on the well ventilated cavity to deal with any interstitial condensation and/or penetration (it's not rendered externally).

And yes, all internal walls are salt-poisoned to a greater or lesser extent which had evidently caused most of the wetness in the original plaster. Once stripped to bare brick and not lived in, the walls dried bone dry and stayed dry proving it wasn't "rising". On internal walls without insulation I boarded using a mix of wet dabs and foam adhesive. Internal walls with dabs in what had been the wettest room showed a little salting where the dabs were once we were living there (this showed on 3-4 dabs mid to high up the wall - not around the lower level), whereas rooms boarded with foam were clear. Subsequently around fire places where salting was very evident, we have stripped back again and re-boarded with foam to isolate the salts from room air which has worked perfectly.

 

[stuart45]

This was the internal wall of a barn conversation I worked on years ago. Turned out that manure had been piled up high against the wall and the salts had penetrated the wall. The wet dabs had brought them through to the surface.

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• stuart45
• 11 Sep 2013
• 1