A blog post

How many DPC’s does one House need?

Posted on the 15 May, 2015 at 10:38 am Written by in Case Studies, Damp

Earlier this year Premier Heritage carried out a full damp investigation of a semi-detached Cottage in North Wiltshire following concerns by its owner relating to damp walls in the main Sitting Room. The property which was constructed around 1898 was built with walls of 228mm solid brick and from a stone foundation.

In discussion with the client she confirmed that following her purchase of the property and within a few months, mould and damp patches started to appear along the bottom of the north and east facing walls, she also mentioned that on occasions she could actually see ‘water droplets’ in the corners.

As a result of her concern she contacted a local damp proofing company who diagnosed Rising Damp and recommended a chemical injection damp proof course (DPC). She was advised that given the plasterwork was in good condition and to save her some money and mess within the sitting room, the DPC could be installed from the exterior of the building, thus eliminating the need to hack off and replaster, although he did state that if the walls didn’t dry out with 6- 9 months, then replastering may well be necessary.

Damp wall caused by seasonal Condensation, note traces of mould to corner

Damp wall caused by seasonal Condensation, note traces of mould to corner

The occupant of some 3 years was concerned that the walls within the Sitting Room were repeatedly being affected by Rising Damp, as they were incredible wet, particularly in the corners and always evidently during the winter months!

Following our extensive investigation of not only the internal walls, but also the exterior of the building, the most astonishing feature of this survey was that this Cottage had 3 damp proof courses (DPC’s), the original slate course, a (badly installed) Ceramic Syphon Tube System (circa 1970’s) and the chemical injected system installed by the owners contractor.

Silicone Injection System, with slate course clearly visible below

 

Silicone Injection System, with slate course clearly visible below.

Ceramic Syphon Tube System
Ceramic Syphon Tube System

However from our own investigation and the readings taken and other data recorded at that time, there was no evidence whatsoever to suggest that the Sitting Room (or indeed nay other walls) were affected by Rising Damp, but the walls were in-fact suffering from severe seasonal condensation, and in our opinion this was always the case, given that the walls had a low Thermal Rating (solid brick) and were north facing.

Given that there was no evidence to suggest that the slate damp proof course had failed, it has to be assumed that the two further systems installed, were recommended on the basis of misdiagnosis, ignorance or mis-selling, call it what you like. Unfortunately this is an all so common problem and our client told us that she “had fully intended to call back the original damp proof contractor (who incidentally was not a PCA Member) but found he was no longer trading” as such therefore his guarantee was absolutely worthless.

Interestingly, when we asked if she had a Full Building Survey undertaken prior to her purchase, she confirmed yes, although that no damp was reported; obviously not given that the survey was undertaken in May.

Having confirmed our investigation and diagnosis in writing we were able to provide our client with practical advice and guidance on dealing with the condensation issue, which didn’t on this occasion involve another damp proofing system!!

Note: Premier Heritage undertake specialist damp investigations using a variety of detection systems and instruments, including Digital Hygrometers/ Thermometers, Thermal Imaging and Carbide Masonry Testing for a quick ‘non-destructive’ evaluation of masonry in a building. But one should not rely on these instruments alone, but should be more reliant on the users experience, eyes (visual observations) and more importantly common sense, all of which will tell you far more than moisture measuring instrument’s alone. However these instruments are there to support and aid in the diagnosis of dampness (if used correctly) and as such their importance should not be overlooked.

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