Thermal imaging has made a huge impact and has been of enormous benefit for surveyors investigating damp problems. Britannia Preservation are among the first to use new technologies and thermal imaging has the ability to identify those areas where problems are occurring.
Thermal imaging cameras do not actually see heat; instead, they detect the infrared radiation emitting from the surface of a material or object. Areas that are affected by moisture respond differently to heat than drier areas and this, as well as evaporative cooling, allows these locations to be seen by an infrared camera.
If your house has not been insulated correctly, or even at all, then heat from inside the building will pass more easily to the outside. These locations can be readily identified in a thermal image and are often referred to as cold bridges. In order to produce good images, there must be differences in temperature between the inside and outside of a building, which is why thermal cameras tend to be more useful over the colder months. Temperature differentials can be created by operating the heating system at high levels during other months or through evaporative cooling utilising forced ventilation.
The thermal image of this wall reveals rising damp. |
The thermal image of this skirting board reveals a plumbing leak. |
The dark blue strip in the corner of this Victorian terrace house indicates the location of a significant cold bridge. These areas can be prone to condensation. |
Thermal imaging is a very useful technique for highlighting cooler surfaces that are prone to condensation. In the following series of images taken on the ceiling of a common hall in a block of contemporary apartments, a 'cold bridge' can be seen that precisely corresponds with the location of mould growth.
Mould growth caused by condensation can be seen on the ceiling. |
The thermal image, overlaid on the visible light image, has been faded to indicate the location of the mould relative to the joists above the ceiling. |
Here, the thermal image is shown in full contrast, and it is quite clear that the thermal properties of this ceiling are significantly different. |
Thermal imaging can be used to identify areas where insulation is missing. This technique is also useful to highlight locations in cavity walls where debris is present. During colder weather, a thermal camera used from outside a heated building will highlight areas of missing cavity insulation. Because of heat loss from inside, these locations will appear warmer than areas where insulation is present. Where such areas are located at the base of a wall, and perhaps correspond with dampness internally, it is a very good indication that debris is present in the cavity and the insulation is missing. This assumption can then be confirmed by opening up and inspecting the cavity.
Britannia Preservation's surveyors have been involved with a number of projects where dampness suspected to be rising damp had been caused by debris in the cavity and an absence of insulation. Importantly, the client then knew that the correct solution was to have the debris removed and insulation reinstated, and did not require the installation of a full damp proof course.
Thermal imaging can reveal some surprising conditions that are not otherwise apparent during a standard visual inspection. Britannia Preservation were engaged to advise on the cause of dampness affecting the ground floor walls of a room in a large detached house, built around 1925. The walls had previously been treated for rising damp by a contractor who had since ceased training. Careful diagnosis revealed that the walls were affected by dampness but that this was a result of condensation rather than a reoccurrence of rising damp. Thermal imaging clearly indicated that the base of the affected walls was much cooler than other parts and that this was encouraging condensation to form on the internal surface.
The contractor who had carried out the original works applied a strong cement render to both the internal and external sides of the affected walls. Dense materials are good conductors of heat and subsequent heat loss from inside resulted in the creation of a 'cold bridge' on the area of the wall where the cement render had been applied.
Strong cement renders inhibit evaporation of moisture and are not suitable for application to the external faces of walls. The client was advised to remove this render and replace it with a lime mix to match the existing pebbledash and to insulate the internal face of the walls. This incident clearly indicates the risk when remedial works such as the application of strong cement renders are undertaken without due consideration of the structure and site conditions.
Thermal imaging can also be useful for tracing ingress of ground water into below ground rooms. Britannia Preservation was engaged to investigate damp penetration into the basement of a newly built house in South Yorkshire. Visual evidence and readings obtained with an electronic moisture meter indicated the probable location of water entry, but the basement walls had been dry lined in plasterboard and this hampered the investigation. The client assumed the below ground waterproofing had failed and was expecting major disruptive works.
Rather than exposing the site, which would have involved removing plasterboards and damaging internal finishes and decoration, a thermal imaging camera was used to trace the water seepage. The images suggested that the water source was near a soil stack that extended upwards from the basement to serve the bathrooms on the upper floors. Further investigation was carried out, concentrating on the location of the stack. The defect was subsequently found to be a plumbing leak which was easily repaired, saving the client significant costs that would have been incurred in unnecessary exposure works or waterproofing repairs.
It is easy to assume that damp problems are going to be a ‘worst case scenario’ but in our experience they rarely are. If you want to get to the bottom of your damp problems, contact us now and we will help find the underlying cause.
© Britannia Preservation 2011