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Storm-water enters your roof system through the waterproofing membrane(s) by tears, cuts, poorly sealed penetrations, failed flashings and caps. The insulation below the membrane becomes laden with water that cannot easily evaporate due to the presence of the roof membrane above and the supporting deck below. If left unrepaired, the concrete deck absorbs or traps water, the wood deck rots or the metal deck rusts and water may intrude into the building’s interior. The point at which the water actually shows up inside is not necessarily near the point of original entry but more likely a place where the roof deck is penetrated and not well sealed. Intruding water may also not show up inside until the insulation above the deck is fully saturated and cannot hold more.
Several hours after sunset, areas of the roof that are of a higher mass (wet) retain the absorbed solar heat longer than that of the lower mass (dry) areas. Infrared imagers can detect this heat and “see” or distinguish the warmer, higher mass areas, during a time “window” as thermal patterns of uneven heat dissipation over the roof surface. Eventually, these thermal patterns equalize and the “window” is closed. Heat loss evaluations and other IR services can be performed at the same time.
There are three types of survey instrumentation that are used to either locate or confirm areas of probable moisture in roof systems. The Nuclear gauge which counts moisture slowed neutrons and is the only non-intrusive method for conductive membranes like EPDM, Galvanometric meters (Tramex Compact or Delmhorst) which intrusively measures conductive moisture and Capacitance Meters (Tramex RWS or Moisture Encounter Plus) which are non-intrusive and measure the electrical insulating capacity of the underlying media. The Nuclear gauge is typically used as a confirming technique for infrared imaging or as a stand-alone method with spot readings on a 5’ X 5’ or 10′ X 10′ grid. Due to the need for grid layout, this type of mapping is more labor-intensive as compared to the infrared survey process. Capacitance-style meters are used to provide partial confirmation where infrared images indicate that moisture may be present (see video).
Thermal Imagers distinguish thermal patterns across the surface of a roof membrane that indicate the possible presence of moisture. Likewise, the readings from Nuclear and Capacitance type instrumentation are of the possible presence of moisture although with nuclear, the probability is high. As an example, capacitance readings can be thrown off by surface or sub-surface conductive conditions unknown to the user.
In every case, intrusive membrane penetration must be performed to truly confirm the presence of moisture. In built-up or single membrane rubber systems, small holes (1/4”dia) may be made for thin galvanometer probes that are sensitive to the presence of conductive moisture. The ultimate test is core sampling when the entire cross section of the roof is observed and tested with a core cut from the assembly. The test holes are plugged and repaired (with approved materials) and noted on the roof and drawing for later permanent repair by the servicing roof contractor.
Our Roof Inspections utilize the following instrumentation for imaging and image confirmation: click here to see our Tools of the Trade
The Armco Roof Inspection process incorporates the following methods:
Generally speaking, at least two persons are required for an on-roof survey for safety reasons and according to OSHA, Infraspection and ASTM inspections standards. In some cases where the building owner or facility personnel require independent confirmation, a roof professional may accompany the survey team.
Yes! Checkout this article by Chris Seffrin of the Infraspection Institute about a 22 year old 360,000 square foot built-up roof – many dollars saved over 6 years through precisely applied repairs guided by infrared survey results. See also the slideshow for Existing Roofs.
