Infrared Roof Inspection Standards

About ASTM C-1153

• Infrared was first used to test roofs in the 1960s. The American Society for Testing and Materials, which sets international standards for building materials, originally formulated ASTM C-1153 in the 1980s. The organization is now called ASTM International. The standard lists the minimal conditions under which an accurate test can be conducted.

ASTM C-1153 Standards

• The roof should not have standing water, and there can be no rain for two days before a test is conducted. The wind must be less than 15 miles per hour and the temperature above 50 degrees Fahrenheit. If the inspection is conducted during the day, there should be no direct sunshine on the roof, and there should be 18 degrees Fahrenheit difference between the inside and the outside of the roof.

Related Issues

• RCI, an international association of architects, engineers and consultants who design exterior walls and roofs, lists additional considerations. Infrared testing results are more accurate if the bottom of the deck is coated, painted or fireproofed. A bare steel underdeck yields the worst results. Roofing membranes are sometimes held in place by ballast of small river rocks or concrete pavers. If the ballast is heavy, a successful infrared inspection is likely impossible. If the inspection is conducted during the day, the bottom of the roof should be directly visible.

Roof Types, Insulation

• The sun warms a roof and water that has leaked under the roof at different rates. According to RCI, there is a greater difference in temperature between leaked water in so-called “rubber” roofs than roofs covered with bitumen. Bitumen, also called asphalt, is distilled from petroleum. Rubber roofs include bitumen modified with ethylene propylene diene monomer, or EPDM, and butadiene styrene or atactic polypropylene. Wet fiberglass insulation shows temperature differences sooner but for a shorter duration than other kinds of insulation.