IR scans of tar and gravel roofs

[prospexcom]

How effective are IR scans of tar and gravel roofs this time of year in the cold NE (Washington DC)? Can you gather reliable information on this type of roofing system, and in these cold temperatures. The building was built in 1936, all brick, with a 5,000 sf foot print. Thanks

 

[David Andersen]

There are a few things that are a hindrance; The condition of an old roof often has piles of detached gravel piled up from the wind. This holds solar heat and also cools off slowly. Also bare spots from missing gravel is exposed to solar loading and make the roof hotter in those locations. These two conditions create significant thermal exceptions which are false positives and may hide real exceptions.

Gravel piles often collect in roof depressions which is often associated with roof moisture damage and become hidden.

As for cold weather scans, weather may shorten the window of opportunity where the roof can be scanned, but provides sharp contrast during that time of opportunity.