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Infrared Inspection of Ballasted Roofing Systems

Infrared inspections can help to detect latent moisture within smooth or gravel-surfaced insulated roofing systems. For roofs covered with high-density ballast or pavers, other forms of non-destructive testing such as capacitance or nuclear gauge testing may provide better results.

For infrared inspections performed during post-sunset hours from the exterior of a building, the collection of accurate infrared data is highly dependent upon roof construction. Applicable roof construction is as follows: Built-up or single-ply membrane installed over, and in continuous contact with, a layer of insulation or an insulating deck. Roof may be smooth, granule-surfaced or gravel-surfaced. If gravel-surfaced, stones should be pea sized or smaller with a thickness of less than one inch.

Roofs covered with concrete pavers or river washed ballast (walnut-sized or larger rock) are not candidates for an accurate infrared inspection. In general, the presence of ballast materials will mask the small temperature differentials associated with latent moisture since they are capable of absorbing large amounts of solar energy during daylight hours.

For some ballasted roofs, it may be possible to detect limited thermal patterns associated with latent moisture; however, this is highly dependent upon roof construction, ballast thickness and density, and local weather conditions. In most cases, the presence of ballast will prevent a thermographer from accurately detecting thermal patterns associated with latent moisture.

For ballasted roofs, it is often prudent to utilize either a capacitance or nuclear gauge instead of thermal imaging. In the hands of a competent technician, these technologies will usually provide more accurate data for detecting evidence of latent moisture within ballasted roofing systems.

Infrared inspection of flat roofs is one of the many topics covered in all Infraspection Institute Level I training courses. For more information on thermographer training or to obtain a copy of the Standard for Infrared Inspections of Insulated Roofs, visit Infraspection.com or call us at 609-239-4788.