Many buildings today have multiple-construction roofs, in which a newer single-ply membrane roof has been installed over an older roof, typically of traditional “built-up” construction. Such structures pose special challenges to the professional nondestructive technician.

In most cases, neither thermography nor nuclear testing can by themselves adequately gauge the moisture in the total roof system. The heat loss patterns detected by the infrared camera must be supplemented by the ability of the nuclear gauge to probe underlying sections of the roof system.

After overlaying the data from the two testing methods, we can perform a comparative analysis to determine the moisture status of both the newer roof and the older roof beneath it.