IR inspections can be performed for flat or low slope roofs consisting of either a built up or single-ply membrane installed over, and in continuous contact with, a layer of insulation or an insulating deck. Roof may be either smooth, granule or gravel surfaced. If gravel surfaced, stones should be pea sized or smaller.
Spray applied foam roofs may also be similarly inspected.
For single ply roofs, membrane material may consist of of EPDM, modified bitumen or thermoplastic materials. While thermoplastics have a glossy surface, their emittance is still quite high.
As stated before, membrane color will not affect the inspection; however, any smooth-surfaced membrane, including black asphalt, roof can be quite reflective. This phenomena is especially noticeable during inspections conducted from rooftop level with a handheld imager. It will be even more noticeable if the roof has an aluminum coating and/or one is inspecting on a clear, cold night. Under such conditions, it is possible to miss significant quantities of moisture regardless of how careful the thermographer is.
To help offset the reflectivity of smooth membranes, I use a short wave imager whenever inspecting any smooth-surfaced roof. During the past 25 years, I have inspected millions of square feet of flat roofs and have never had a problem getting good results on TPO, PVC, EPDM, or BUR.
Unfortunately, portable SW imagers are no longer being produced on a large scale. Flir Systems does offer refurbished SW imagers with a warranty. Although SW imagers are more expensive that microbolometers, they can mean the difference between being able to perform an inspection or not.
Infrared Inspections of Smooth Surfaced Roofs is a topic I recently authored for IRINFO.ORG. Should you be interested, it can be found at the following URL:
Hope this helps.