For instance,
infrared thermography can be a very effective tool for roof asset management. IR roof moisture surveys are performed on roofs to quantify the extent of roof moisture (water) that is inside the roof system. Infrared thermography is not leak management. No matter how the water got into the substrate, the purpose of this type of survey is simply to find and document where the water is located. Extending the life of a roof will save the owner the expense and aggravation of re-roofing or re-covering. Re-roofing means that the roof is taken down to the decking and replaced completely. Re-covering means that the waterproofing layer(s) are removed, the wet insulation is removed and replaced and a new waterproofing layer is put down. The cost of an infrared roof moisture survey is three to five CENTS per square foot. It cost between three and five DOLLARS per square foot to repair/replace roofs, so knowing the exact location of the subsurface water is extremely useful information, since only those areas that are damaged need to be repaired. This information is used to plan budgets and when needed, as a bid document for contracting repairs and/or replacement of the roof.
Keywords: Infrared, Thermography, Roof, Roof Asset Management, Infrared Roof Moisture Survey.
ROOF MAINTENANCE IN GENERAL
The ravages of sun, wind, rain, snow, chemicals, leakage, rapid changes in temperature and time – will eventually cause every roof to fail. Some roofs last 40-50 years…when they are well maintained. Owners may believe that a roof warranty will somehow protect them from having to do maintenance. Not so, as roof warranties are written by roofing manufacturers for the purpose of protecting themselves from liability. For example, often a warranty is written so that if improperly installed or defective roofing materials are used on a roof and water leaks into the electrical switchgear room causing an explosion, the roofing manufacturer will replace the materials, the roofer will reinstall the materials, but the building owner has to pay for the replacement of the switchgear and any downtime that resulted from the failure. Also, the roofer’s and roofing manufacturer’s liability, in the case of roof failures are also reduced by vaguely written roof warranties, which do not define words like “regular” or “routine” maintenance. Not accepting the roof warranty is not the answer, since the roof will not be installed unless the owner agrees to the warranty. To eliminate these problems, the building owner should have an agreement with a qualified roofer or roof consultant to inspect and maintain the roof (in accordance with the terms of the warranty) at least once a year.
Waterproofing problems manifest themselves in two ways: Leakage and entrained moisture contamination. Leakage is pretty simple, although the leak inside the building rarely directly relates to the exact spot on the roof, since the water flows down the slope of the roof to a spot that is not sealed and into the building at that point. Most leaks occur where the waterproofing is sealed or where there is a penetration of the roof. Since most types of roof systems absorb some amount of water, it is harder to find the exact spot of water contamination in the insulation because it may not leak into the building until it has absorbed all the water it can hold. There are three types of surveys that are used to find water in a roof. Nuclear gauges-which count neutrons, capacitance meters-which measure resistance, and infrared-which measures heat. Both nuclear gauges and capacitance meters are used to take spot readings on a 10′ X 10′ or 20′ X 20′ grid on the roof. These measurements are used to extrapolate where the water is from the readings obtained from the gauge. They are good for types of roofs that do not gain or lose much solar energy and therefore, do not lend themselves to infrared.
BASICS OF INFRARED ROOF MOISTURE SURVEYS
During the day, the sun radiates energy onto the roof and into the roof substrate, and then at night, the roof radiates the heat back into outer space (See Figure 1). This is called radiational cooling. Areas of the roof that are of a higher mass (wet) retain this heat longer than that of the lower mass (dry) areas. Infrared imagers can detect this heat and “see” the warmer, higher mass areas, during the “window” of uneven heat dissipation. roof cleaning in southampton