IR Inspections of Roofs with Insulating Decks
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IR Inspections of Roofs with Insulating Decks
Tip written by: Infraspection Institute
Thermography is a proven technique for inspecting insulated, low-slope roofing systems. Under the proper conditions, thermography may also be used to inspect uninsulated roofs that are constructed with an insulating deck.
Flat or low slope roofs, also known as insulated roofs, are a common feature found in commercial construction. Applicable construction includes smooth, gravel, or granule-surfaced membranes having a layer of insulation located between the deck and the membrane and in continuous contact with the underside of the membrane.
As an alternative, some roof membranes may be installed without insulation directly over insulating roof decks. Common insulating deck materials include gypsum and lightweight concrete. Typically, these materials are mixed to produce a liquid slurry which is poured and formed in place during construction. After solidifying and drying sufficiently, the roof membrane is laid directly over the insulating deck.
Because wet-applied decks can retain significant quantities of construction water, thermographically inspecting these roofs can be a challenge. In some cases, it may take several months for construction water to dry out making it difficult or impossible to detect thermal patterns associated with water ingress. In other cases, water entering these systems due to a leak may diffuse or dry out quickly.
Selecting optimal site and weather conditions is of paramount importance when performing infrared inspections of uninsulated roofs with gypsum or lightweight concrete decks. Among these are:
- Rainfall within previous 48 hours
- Completely dry roof surface at sunrise
- Daytime high temperatures above 40ºF and little or no wind
- Mostly sunny day followed by clear evening with no wind and temperatures above 32ºF
Infrared inspections should be conducted by walking over the subject roof(s) after sunset. The inspection should be methodically conducted and no inexplicable anomaly should be overlooked. All thermal data should be verified by invasive moisture meter readings and core samples. Core samples should be gravimetrically analyzed to ascertain that moisture content is acceptable even if the roof appears to be uniformly dry.
Infrared inspection of flat roofs and proper equipment selection are two of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or to register for a course, visit Infraspection Institute online or call us at 609-239-4788.
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