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 Roof Restoration Sydney 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 . 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.
Areas of the roof that are wet retain heat longer than dry areas.
Some roofs and insulation types or combinations do not absorb any water. These roofs leak straight into the building. Even roofs, which have insulation types that do absorb water, some do not exhibit a good infrared signal, primarily for two reasons. 1) The surface is too reflective, and the roof’s ballast is so thick (or dense), that daylight radiation is not absorbed into the substrate (insulation), therefore it cannot be emitted back into the atmosphere at night. Even with a strong infrared signal, factors on the roof can affect the analysis and interpretation of the data. Some of these factors: water between multiple layers, old patches, heavy flood coats, reflective coatings, heat-producing equipment under the roof –or heat blowing down onto the roof, stains, ponding water on the roof, heavy build-up of ballast at parapet walls and along edges, etc. These roofs should be inspected by other methods as described above.