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DISCLAIMER:

These notes and web pages are for information and general guidance only and are not to be considered as a complete technical description of the subjects covered. Furthermore, due to the nature of old constructions and the large number of variables that need to be considered it would not be possible to form a judgment based solely on these pages. The author and anyone else representing Reddock Consultancies cannot accept liability for the consequences of anyone acting on the information here given

© 2007 to 2017 Reddock Consultancies Limited. Architectural, Aerospace, Automotive & Naval Consultants

Warning :

Data and images from High Tech instruments such as IR cameras and humidity meters for detecting dampness need interpretation and in the hands of the inexperienced are dangerous. Low Tech "Conductivity Meters" sometimes called "Moisture Meters" that cost around £20 from Maplin etc. and favoured by Estate Agents and disreputable Damp Proofing Companies measure conductivity such as condensation and deposited salts and not necessarily dampness.

IR Camera :

Thermography (IR camera) is very useful in the detection of dampness. When surfaces are warmed, damp patches remain relatively cold due to evaporative cooling as moisture is lost from the surface. The situation is more complex when moisture is held at depth, as may be the case in a solid masonry structure. Evaporative cooling can only take place when water is present on or near the surface. When moisture is trapped below the surface and heating has been of sufficient intensity and duration, trapped water will show up as a hot spot. This potentially confusing effect is caused by differences in the thermal capacity of the water and the wall. Water holds heat longer than dry stone, so during cooling a mass of water inside a wall shows up as a warm patch. Whether cooling down or warming up, a wet wall will change temperature more slowly than a dry wall.

(from "Thermal Imaging in the investigation of solid masonry structures" by Maureen Young)

 

 

 

Thermography : Some areas of dampness cannot be seen by the naked eye and this were an IR camera comes in as an invaluable tool

Hygrometry : A Hygrometer measures the amount of moisture in air and it's "Dew Point" and indicates if condensation can occur on a wall. Furthermore, it can be used to accurately measure the amount of moisture in a wall to confirm or otherwise true dampness