CAG - Construction Analytics Group

Great thermography does not just rely upon temperature differential between interior and exterior, but also what is referred to as "rate of change of temperature".

Think about it - assuming a warm, sunny day, roof temperature gradually increases, along with underlying substrate layers. At some point, roofing materials will arrive at a relatively similar temperature. Even if an interior/exterior temperate differential still exists at this point, the differential occurs vertically, e.g. colder inside and warmer outside. Likewise, temperature gradient in the roof assembly occurs vertically. Conducting thermography at this time is not effective.

While vertical temperature differential is important, horizontal temperature differential occurs during a "rate of change of temperature".

"Rate of change of temperature" predominantly occurs during dawn and dusk. However, cooling rates are more constant across the roof surface a minimum of one hour after sunset, in part due to solar radiation exposure being eliminated. Conversely, when the sun comes up in the morning, uneven heating of the roof surface and reflectivity of solar radiation is problematic for thermographers.

In Colorado, we have an added benefit of large temperature swings (especially in fall, winter, and spring months).

If an exterior temperature drops from 67 degrees Fahrenheit at 6:00pm to 55 degrees Fahrenheit one hour after sunset, a sharp "rate of change of temperature" occurs. This is the prime time to conduct thermography surveys.

"Rate of change of temperature" results in thermal contrasts between dry and wet materials. Thermal contrasts provide great imagery.

Next step - destructive testing.

Roofing professionals need to be able to properly distinguish between minimum height requirements as they relate to rooftop mechanical equipment versus minimum flashing height requirements specific to roofing.

For example, certain building codes, such as the 2022 Denver Building & Fire Code (which amends the 2021 International Codes) states that "Mechanical equipment placed or reset on roofing shall be supported on a minimum 8-inch (203-mm) curbs, platforms, or legs bearing on the decking and made watertight. The 8-inch (203-mm) raised height shall be measured from the top of the installed roofing assembly to the top of the curb, platforms, or legs." (see Section 1503.2.2)

This specific requirement relates to mechanical equipment, not roofing. A quick solution to inadequate curb height is commonly to install curb adapters, which increases the height of the rooftop mechanical unit from the finished roof surface (Photograph 1). However, this configuration overlooks the importance of the minimum roof flashing height, which is also commonly 8-inches (203-mm).

For example, "Extend all flashings a minimum of 8" (20.32 cm) above the roof level." (See: JM TPO Installation Guide, p. 6)

Photograph 2 shows TPO base flashing having a height of less than 3-inches from the finished roof surface.

We are excited to announce that Sean O'Malley, RRO® successfully obtained his IICRC WRT (Water Damage Restoration Technician) certification! Well done!