ROOF THERMOGRAPHY

OVERVIEW

Infrared thermal imaging is a proven method to find wet insulation in flat roofs and moisture in building walls. An infrared roof moisture survey can locate and document how much of your roof contains moisture. Depending on the amount of saturation found during the infrared roof survey, you may be able to make roof repairs surgically by removing only the wet areas and without the expense of replacing the entire roof. It is also possible that the thermal inspection will reveal extensive saturation, encompassing large areas of the roof, confirming and justifying the cost of a full replacement. The data from an infrared inspection will allow you and your roofing expert to make an informed repair/replace decision.

Thermographic roof inspection should be used on a periodic basis to monitor the condition of a roof so small issues can be repaired now, preventing them from becoming larger roof problems in the future. Roof thermography can be used as a quality control inspection for new roofs and to access the condition of a roof. Infrared roof inspections can provide valuable information about the

roof prior to the sale or purchase of a building, negotiating a new lease or to establish the condition of the roof prior to a lease termination.

Infrared flat roof moisture inspection is a diagnostic tool available to property managers and building owners which provides them the hard data necessary for making objective, information backed roof maintenance decisions. These decisions can support the development of more intelligent and cost effective roof asset management programs.

DETAIL

Inspecting insulated flat and low-sloped roofs, and EIFS wall (Exterior Insulation Finish System) is an application where only thermal imaging is able to detect trapped moisture in very fine detail over a large surface area with 100% coverage!

Because roofs are not exothermic and do not generate their own heat, an infrared inspection technique called “Active” thermography is employed. It is called “Active” because an external source of heat is used to drive energy into the roof. The heat energy stored in the roof then will radiate out at different rates over different time spans depending on if the roofing materials are wet or dry. It is this radiated heat, which the thermal imager is “seeing” during an infrared roof or EIFS survey.

The best available heat source for driving heat energy into a large surface area such as building roof or wall is the sun. In contrast, when using “Passive” thermography, it is the target itself self which produces the heat captured by the imager such as a termite nest in a wall, or a hot electrical connection. These items make their own heat and no external stimulus is required to image them.

For roofing and EIFS applications, we use the sun to heat up the roof or wall materials. As the sun rises and radiates onto the building or wall, wet materials having higher thermal mass warm up slowly and dry materials with lower thermal mass heat up quickly. Thermal imaging can be performed during this time of uneven heating between the wet and dry.

In practice, most roof thermal imaging takes place after sunset during the cooling off cycle when wet materials, which will retain more heat will stay warm longer than the dry materials. The temperature difference between the warmer wet and cooler dry materials is what the imager sees. Under the right conditions, the temperature difference will remain visible for several hours allowing the thermographer adequate time to complete the inspection.

For this type of infrared inspection process to be successful, it is important to have an absorbent layer of material layer such as some insulations, foams or wood based boards under the waterproofing membrane or between the wall panels to hold the trapped moisture, which in turn holds the heat. Roofs without an absorbent layer of material are not good candidates for an infrared survey.

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