For steep-sloped roofing systems, aesthetics plays a major role in roofing decisions such as whether to use tile, slate, painted metal, asphalt, or wood shingles or shakes. However, for commercial low-slope roofing, aesthetics is much less important than these more critical issues:
- Keeping water out of the building
- Prolonging roof life
- Protecting roof warranties
- Meeting building codes for fire, R-value, wind and drainage
- Serving as a platform for rooftop equipment
In recent years, additional criteria such as reflectivity (albedo), emissivity, revised energy codes, and recyclability have gained more importance.
Roughly two-thirds of commercial roof activity today consists of re-covering or re-roofing existing buildings. While periodic inspection and routine maintenance are the best investment a building owner can make, far too often the roof is out of sight, out of mind (until it leaks, of course).
Below, learn how to reduce leak potential and prolong roof life through routine inspections and maintenance. Important resources on this subject include Corps of Engineers publications on its computerized ROOFER program and RoofPoint, the roofing rating system by the Center for Environmental Innovation in Roofing.
Forthcoming columns will look at roof coatings and liquid membranes as important parts of sustainability and address what, where, and when coatings should be used as part of an overall roof management program.
Keeping the Building Dry
Early in the life of a low-slope roof system, leakage is often a consequence of poor workmanship, damage by other trades, or poor detailing. Address this by engaging a roof consultant to provide and review specifications and details. Later on during the construction phase, use a full-time roof observer to provide quality assurance.
A relatively new document, Standard Practice for Quality Assurance Observation of Roof Construction and Repair (ASTM D7186), can go a long way towards a successful roof launch. Also look into seminars by RCI that lead to certification as a Registered Roof Consultant (RRC) or Registered Roof Observer (RRO). Both programs will help you get a roof project off to a good start. For your reference, you may also want to order a copy of the newly released NRCA Construction Details, a supplement to AutoCAD software that contains 573 customizable details from past NRCA roofing manuals.
Poor detailing, especially of roof flashings and counterflashings, is a major source of early leakage. Often new equipment is installed after the roof has been put in service. This lapse can also void a roof warranty if the installation is not approved by the warranty supplier.