Key Takeaways:
Two kinds of calls come across my desk. The first is the good one: A roof has served its building well for years. It is time to plan the replacement, and we celebrate a successful design that has stood the test of time. The second is not good. Something has gone wrong — either during a difficult installation or years before the warranty was up — and the maintenance and engineering manager needs to know the reason.
After more than 30 years as an architect and building enclosure specialist, I have noticed that the roofs in the first category tend to have something in common. Someone insisted the designer — contractor, consultant, architect or whoever owns the roof design — work directly with the manufacturer while the system was still on paper.
That strategy sounds obvious but isn’t. The collaboration I mean goes well past a designer checking in with a manufacturer’s rep or a contractor pulling stocking reports. Here is the reason it matters to facility managers and building owners.
Maybe you or someone on your team have the background to manage a reroofing project. If not, start here. Nearly every U.S. jurisdiction sets minimum code performance requirements for low-slope membrane roofs. For two of the requirements, confirming a design complies means working directly with the manufacturer:
Fire classification. Most roof systems must be at least Class B, and occasionally Class A. Fire classification measures how well a roof resists fire on its own surface, such as rooftop equipment or solar panels igniting or embers landing from a nearby fire.
Most jurisdictions require testing to ASTM E108 or UL 790, equivalent standards both titled, Standard Test Methods for Fire Tests of Roof Coverings. Systems earn Class A — the most resistant — Class B, Class C or no rating. Ratings apply to the whole assembly, not individual products. Testing covers every layer — membrane, cover board, insulation and vapor retarder — as well as the deck. A system rated over concrete might rate differently over steel. Some classifications also carry limits on slope or insulation thickness.
Manufacturers run ASTM E108 or UL 790 tests to determine which product combinations earn which classifications. Careful designers work with manufacturers to confirm that a design achieves the classification a given building requires. Because every component contributes, any substitution can change the rating, and manufacturers can confirm their test data whether a particular system achieves the required classification on a particular deck type.
Wind pressure uplift resistance. Like fire classification, wind pressure uplift resistance is tested on components installed as complete systems. Most jurisdictions require mechanically attached or adhered systems to be tested per FM 4474, UL 580 or UL 1897. Manufacturers run these tests and can provide attachment criteria that achieve a given uplift resistance in pounds per square foot. That tested pressure must generally exceed the minimum design uplift pressure the designer calculates under code. Code compliance does not guarantee performance, but it is worth verifying that roof systems meet minimum safety standards for fire classification and wind uplift resistance. Many problematic roofs are found to be under-designed in these areas.
Beyond code compliance, maintaining relationships with roof system manufacturers offers additional advantages:
Start with a phone call. Look up the manufacturer's main number, ask for the regional representative covering your project location, and start the conversation before the design is finished. The best designers keep those relationships going for years across many projects. Do that, and the call you get 30 years from now is the good one — a roof that served its building well and an owner ready to plan the next.
Jason Wilen, AIA, NCARB, CDT, RRO, is a board-certified architect licensed in 11 states and a specialist in building enclosures with over 30 years of experience. He is a principal at Klein & Hoffman's Chicago office, where he leads the firm's roof system and waterproofing rehabilitation projects. He has also authored more than 25 feature articles for local and national trade journals and magazines. He will be a regular columnist for FacilitiesNet on roofing topics.
