Infrared Thermography is particularly well suited to find the thermal
anomalies created by trapped moisture under roofing membrane.
How it Works
All flat roofing systems have several inches of insulation material
sandwiched between the membrane and roof deck. When a leak
develops, this insulating material absorbs some of the water that
penetrates the membrane. The added water in this material increases
the thermal mass as compared to dry insulating material.
During daylight hours the radiant heat of the sun heats the combined
roof structure. After sunset, the roof begins to shed this accumulated
heat back to the atmosphere. The added thermal mass of the moist
insulation holds this heat longer. During this time there is a window of
opportunity when a skilled thermographer will be able to image these
warmer areas. The results can be quite dramatic.
Thermography measures temperatures in materials and creates an
image based on these temperatures. The images can then be saved
by the technician and inspected for anomalies which might indicate
moisture, overheating, leakage and heat loss in buildings and many
other applications. All materials have different thermal properties which
allow for measurement of those differences. As heat travels to cold, the
temperatures equalize, this is called “thermal equilibrium”. This is why
most surveys must be performed during thermal windows (time
periods). This is usually 1-3 hours after sunset and 1-2 hours after
sunrise. It is during these specific thermal windows that the most useful
information can be gathered using non-contact methods.
During our infrared roof surveys we follow guidelines described in
ASTM C1153-90, “Standard Practice for the Location of Wet Insulation
in Roofing Systems Using Infrared Imaging”. This includes scanning the
roof, verifying anomalies using core samples and/or electronic
moisture detection, marking of suspect areas for contractors to repair
and finally working with contractor to verify the success of repair work.
The ASTM Standard outlines the minimum criteria for infrared imaging
systems, conditions for performing surveys, verification procedures
and other important issues. The company you choose to perform such
operations should be fully aware of special conditions and limitations
which could affect the outcome of such surveys. Performed properly,
infrared roof survey’s can be an excellent tool in maintaining, repairing
and deciding the proper corrective action for your roofing system.
:: Infra Red Sanning ::