Rising Damp to Listed Building?

Rising Damp to Historic Listed Building?
Rising Damp to Historic Listed Building?
Rising Damp to Historic Listed Building?

I recently attended this beautiful old listed building to investigate alleged rising damp in the ground floor hall of this building. This was a localised, as opposed to a generalised problem but my approach is broadly similar, irrespective of the age of the property… If I prove that there is moisture at depth in the masonry, then I proceed to look for the cause of that moisture, and that usually encompasses leak investigation. More specifically, we may look for drain leaks, water main leaks, leaking rainwater goods or storm drains, other internal plumbing leaks or central heating system leaks.

Moisture Testing

Visual decorative spoiling was seen to be affecting walls in the hall and testing for moisture at depth in the masonry allowed me to look at moisture profiles which aid in directing me towards the seat of the damp. Figure 1 below shows that we have a lateral moisture profile with a high reading of 11.4% total moisture content, so of course this would tend to support the view that a subfloor leak is somewhere in the region of this high reading.

Moisture profiles point to the seat of the damp
Figure 1. Moisture profiles point to the seat of the damp

Floor Construction

Unusually, the floor construction in the hall varied, with one section of the hall floor being of floating timber construction, whilst another section was solid concrete. The walls affected by decorative spoiling and damp were located to the solid floored area. Interestingly, I could access a service hatch in the timber floor and could clearly see how moisture was affecting the joists ends where they were supported in the solid floor. This provided further visual evidence in support of a sub-floor leak.

Moisture to joist end
Moisture to joist end

Further Evidence of Sub-Floor Leak

It was notable that we recorded increased scan readings for moisture to a section of solid floor closest to the highest wall reading of 11.4%. However, thermal imaging can often be incredibly useful in locating leaks to central heating pipework when the pipes are hot, as it was in this case and I was able to be very specific as to where the client should excavate the floor to repair the pipework.

Thermal Imaging highlights a leak to a heating pipe
Thermal Imaging highlights a leak to a heating pipe

What would a Damp Proofer Have Done?

I have used this blog as something of a case study to illustrate that whilst these walls were affected by rising damp, it was not naturally occurring, and it rarely is. The answer is to locate and rectify the leak that has driven up local ground moisture, which in turn has driven up wall base damp. Had a local damp proofing company been called in then the likely outcome would be that the property would have been subjected to damaging retrofit DPC injection, which would have masked the problem for a very short time before this leak got completely out of hand.

One response to “Rising Damp to Listed Building?”

  1. A avatar
    A

    Hi,

    Great website. What is the best way forward here please?

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