Infrared Thermal Imaging and Flat Roofs
Flat Roofs are often ignored as part of the building maintenance plan. The roof only gets attention when it makes itself known, and the only time that happens is when it leaks. Forty percent of all new flat roofs develop serious problems within one year of installation.
The National Roofing Contractors Association estimated that the sources of the problems are due to:
- 50%- poor workmanship
- 20%-poor design
- 10%-material failures
- 15%-poor maintenance
Infrared Advantages:
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The losses from premature flat roof failure run into billions of dollars every year. These dollars are lost, and not available to support or expand plant operation. The primary costs associated with flat roof failures include the following:
Excessive energy consumption due to reduced insulation value of wet insulation.
Losses due to water leakage into the building, resulting in problems ranging from minor nuisances to catastrophic and life-threatening situations. Leaking flat roofs can cause total building outages when water invades electrical switch gear and critical production equipment.
Damage to the flat roof membrane and the structural roof components caused by trapped moisture in the roof assembly. There are numerous accounts of people being seriously injured or killed when they fall through a flat roof because the roof lost structural integrity due to water damage.
 This infrared inspection was conducted during daylight hours, and the dark purple area reveals a central portion of the roof saturated with moisture and in need of repair. |
Loss of salvage value of the roof insulation at the time of membrane replacement because it has become wet. The cost of disposing and replacing insulation can cost $3-$5/square foot.
The average life of a new flat roof in Canada is seven years. Because some flat roofs last over 30 years, it is clear that a lot of money is being spent that could be put to better use. How can this be accomplished? The answer is easy – Maintain the Roof!!
Understand root cause of flat roof decline
When a flat roof leaks, the mission of the maintenance person is to find the leak and stop the intrusion of water. This is often not an easy task, as the leak may well have been caused by a failure in the flashing or a penetration in the membrane far from where the water is leaking into the building. When water first penetrates the membrane, it will start to be absorbed by the insulation and other roof components. If the insulation is nonabsorbent, the water may run for great distances before it finds a route to the interior.
Understand how maintaining flat roofs will result in longer roof life
The job of the infrared thermographer is not to simply find the leak, but to locate the extent of the wet insulation by its thermal difference. A visual inspection of this area will almost always locate the point of water entry.
By just plugging the leak, large quantities of water are left in the roof assembly to cause further damage as roof components rust, rot and degrade. Repairs must be made to replace the damaged insulation and patch in new membrane. Only by repairing both the membrane and the insulation can the flat roof life be extended.
Infrared roof moisture inspection surveys are far and away the easiest way to maintain a leak free roof and to extend the life of the flat roof
The brighter orange area represents moisture intrusion into the insulation
Understand the theory of IR roof inspections
Normally there is little or no water within a flat roof assembly. When a leak develops, water enters the assemble and depending on
the type of insulation system is either absorbed by the insulation or runs to the cracks between the nonabsorbent insulation. When water enters the roof assembly it is there for a long time. Accelerated testing has proved that once wet, a flat roof will not dry out during the life of the roof, even if there is never another leak.
Thermal capacitance is the physical property of a material’s ability to store heat. The materials in a roof assembly have relatively low thermal capacitance, especially when compared to water. Water requires a lot of energy to raise its temperature and likewise must release a lot of energy to cool down.
Water Penetration around roof stacks
This is the basis of thermal roof inspections: dry roof insulation will heat up quickly when heated by the sun, while wet roof insulation will heat up slowly. Later in the day, after the sun has gone down, the roof starts to cool off. The dry insulation cools down quickly while the wet insulation cools off slowly. When the dry insulation reaches a temperature cooler than the wet insulation, the thermographer can see the wet areas as warmer.