Bituminous roofing systems: Multiple layers and field assembly mean that blisters between layers can occur. Avoid traffic over blisters and promptly repair broken blisters. Neither asphalt nor coal tar pitch weathers well if its opaque surfacing has eroded away. Simple repairs can be done with asphalt mastic and fabric such as woven glass fiber mesh or non-woven polyester.

Polymer-modified bituminous systems: SBS is generally installed as a base sheet and mineral-surfaced cap sheet combo. These sheets can be installed and patched with hot asphalt. APP has a higher melt point, so torch application is used instead of mopping because it permits localized patching. Both APP and SBS systems require trained applicators and tools.

Elastomeric roofing systems: Large prefabricated panels of EPDM have extraordinary weather resistance but rely upon relatively narrow seams for water-tightness. Surface cleaning, priming, and application of target pieces of new membrane or flashing are needed. Many repair materials have a short shelf life, so the roofing contractor that installed and/or one that is approved by the roof warrantor may be needed.

Thermoplastic roofing systems: These sheets are generally light-colored and internally reinforced with scrim or fabric. Subcategories include PVC, TPO, KEE, and CSPE. Repairs depend upon weldability, which, in turn, may require surface preparation and hot-air fusion. Expect erosion down to the scrim. Special techniques for resurfacing depend upon the chemical make-up of the original membrane.

All roofing systems: All roofing systems should be visually inspected for deficiencies and failures, but some components are hidden from view. Depending upon the design of the system (when a vapor retarder is in place, for example), design may actually hide damage from water intrusion. Click here for a sample visual inspection sheet.

Periodically, or when water intrusion is expected, consider bringing in an expert to look for water in roof insulation using infrared scanning, capacitance, or neutron backscattering techniques and recommend how to deal with moisture before utility expenses soar and structural and interior damage result. Quest Construction Products details how to recognize damage patterns and perform field tests in a presentation from the International Roof Coatings Conference here.

A note on spray foam insulation: Sprayed polyurethane foam consists of expanded two-component polyurethane foam followed by an opaque coating of liquid urethane, acrylic, or silicone elastomer. It generally requires recoating before the surfacing erodes away because the underlying foam is not UV-resistant. Typical recoating will be required within 7-10 years. Field repairs are generally needed for punctures using a compatible caulk to fill in voids.

5) Improve Safety
Designate a single employee as the in-house roof overseer with reliance upon qualified outside experts as required. Roofing conventions and webinars are available, as well as training programs conducted by material manufacturers. These training programs should focus expressly on the roof systems in place on your building complex. Extend the training to any other personnel who need to access a roof surface and make sure the MSDS is available and understood.

Richard (Dick) L. Fricklas was technical director emeritus of the Roofing Industry Educational Institute prior to his retirement. He is co-author of The Manual of Low Slope Roofing Systems and continues to participate in seminars for the University of Wisconsin and RCI Inc., the Institute of Roofing, Waterproofing, and Building Envelope Professionals. His honors include the William C. Cullen Award and Walter C. Voss Award from ASTM, the J. A. Piper Award from NRCA, the William C. Correll award from RCI, and the James Q. McCawley Award from the MRCA. Dick holds honorary memberships in both ASTM and RCI Inc.

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