Detecting problems in buildings using infrared cameras

by Darren

Locating moisture problems in buildings before they become apparent can prevent expensive damage.

From storm damage to everyday plumbing and roof leaks, moisture damage in buildings can be very expensive. According to Comtest, the key is identifying and locating moisture problems before secondary damages escalate.

Infrared cameras, also known as thermal imagers, have become powerful tools for locating moisture problems in buildings. Instead of inspecting inch by inch with a moisture meter, an infrared camera allows one to scan an entire room in a matter of minutes. By locating the thermal changes from evaporative moisture cooling (EMC) in drywalls, carpets, ceiling tiles and more, inspectors can moisture map the entire building and isolate problems before providing an estimate for remediation.

How it works
An infrared camera can detect trapped moisture beneath multiple layers of materials without any surface indication. Different to a moisture meter, it locates unique thermal patterns created by the temperature differential caused by evaporative moisture cooling on a given surface creates.

This evaporation effect applies primarily to interior inspections where the temperature and other elements are controlled. Exceptions include certain types of roof systems, where wet material in the ceiling creates a warmer thermal pattern as the sun heats water trapped in the roof materials.

Although building interiors are usually controlled environments, inspectors must still account for several factors:

• Air temperature
Warm supply air can mask wet materials by warming the surface enough to distort or negate the thermal pattern created by evaporation. In comparison, cold air from an air-conditioning supply can create a thermal pattern similar to that of a moisture problem, thus creating a false positive.

During water loss, the drying equipment inside the structure creates an enormous amount of heat. Numerous air movers direct high-volume, high-pressure warm air to the wet surfaces, thereby increasing the chance of a false negative. The warm air from the air movers can mask the cooler thermal pattern created by EMC, giving the user the impression that the material is dry. And although the ambient air alone does not adversely affect the thermal pattern of wet to dry, placement of the equipment can have an impact.

Missing or compressed wall insulation on a warm, sunny day can cause the materials and moisture inside a wall cavity to heat up to a point where the thermal pattern becomes negated or distorted. In comparison, on a cold day it can create a cooler thermal pattern that is similar to that of wet materials. In both situations, verification of the presence of moisture must be confirmed with a moisture meter.

• Ceramic tile
Most interior building materials have high emissive values, making them perfect candidates for thermal imaging. However, locating moisture beneath ceramic tiles and certain other floor and wall coverings can be difficult. Because the moisture is in most cases actually in the subfloor and not in the floor covering itself, the temperature changes in the web subfloor may not transfer through to the surface of the floor covering. Unwanted reflections make matters worse by distorting the true thermal pattern.

• Windows, siding and exteriors
When inspecting for exterior moisture infiltration from windows, siding or other exterior components, it can take an hour or longer after wetting for a thermal pattern to become apparent on the interior.

Temperature changes from wet to dry as slight as 0,5°F to greater than 10°F can be observed. During the drying of a building, the temperature differential between wet and dry will go up or down depending on the ambient temperature of the building and moisture content of the material. For the biggest part, temperature differentials are the greatest during the first 24 to 36 hours.

Comtest highlights that the financial impact of undetected moisture problems in buildings is tremendous. While moisture meters continue to provide final confirmation, the need to locate moisture in buildings quickly and accurately remains a challenge and by using infrared technology, building inspectors and contractors can reduce liability and inspection time.

Tel: 011 608 8520
Website: www.comtest.co.za

(2 pics on the left)
Water running underneath the tile deck into the unit below.

(2 pics on the right)
Moisture in drywall is not visible (top) without the use of a thermal imager (bottom).

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