The secret to successful flat roof surveys is……….timing!
Thermal imaging is a great tool for a technician, but it is only a tool – and it is rarely just a matter of simply turning up and pointing the camera in right direction.
Thermal imaging is a great tool for a technician, but it is only a tool - and it is rarely just a matter of simply turning up and pointing the camera in right direction. Being on the roof at a time when the buildings own heating system and the weather combine to create conditions that ensure that damp and dry areas of roofing have different thermal properties is key.
The image below shows hot spots created by damp insulation at a block of flats in Edinburgh. We marked out the roof with paint to allow further investigation. Our recommendation to the client was to take cores at a sample of areas on the roof to confirm our findings - the contractor had previously stated that they believed there was no problems with the roof. And there wasn't - not on the roof surface anyway, but there was retained moisture from previous leaks and water ingress from around the parapet walls. Our survey provided sufficient evidence to ensure that further investigation and remediation could be undertaken.
Sometimes a roof survey doesn't highlight anything, such as in the image below. Does that mean there aren't any problems, or just that the problem hasn't been picked up?! It could be either, however by having identified problems in other areas in the same weather conditions, we knew we had the timing right.
So what IS the best time to survey? In the case of this roof it was in the two to three hours after sunset and a long sunny day. Over the course of the day dry and wet areas heat up and reach equilibrium, after the sun goes down the dry bits cool down faster. Sometimes that is very immediate, sometimes it takes several hours. Sometimes the best time for a survey is in the morning, where the opposite heating rules apply.
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If you're experiencing problems with leaks, or have recently had roofing work completed and have concerns