Roof Design Code and Regulation Changes

by Jeff Evans, RRC, Senior Consultant and Vice President, Benchmark Inc., a roof consulting firm headquartered in Cedar Rapids, IA.

One of the challenges in our industry is to stay current with the rules and regulations that govern roof design. The model building codes are revised every three years. This is one element that requires a designer’s diligence, as states and local governments then modify the codes to suit their needs. Regulations requiring “cool roofing” and restrictions on the use of VOC’s (volatile organic compounds) can make old ways of doing things (that worked just fine last year) obsolete and at odds with the rules.

The constant innovation in roofing products also challenges roof designers, as old standby roofing products leave the marketplace or are modified by the manufacturer and new products enter the roofing arena.

Finally, new technologies such as “green” or vegetative roofing and solar energy change the way we use our roofs. In the case of vegetative roofing, the industry is scrambling to figure out how to comply with building code fire and wind requirements.

Building Codes
Local building codes are a moving target and change the landscape of roof design. A short list of notable changes follow.

California Building Code
California’s Title 24 3008 Building Energy Efficiency Standards becomes effective August 1, 2009. Included in this update of the 2005 standard is the need to use a cool roof product with a three-year aged solar reflectance value greater than 0.55. This has caused several previously approved cool roof products to be delisted.

Title 24 does allow several exceptions to the use of cool roof rated products:

• Wood framed roofs in climate zones 3 and 5, if the insulation value is 25.6 or greater
• Metal building roofs in climate zones 3 and 5, if the insulation value is 20.8 or greater
• Roofs covered with photovoltaic panels
• Roofs with a thermal mass (gravel or pavers) over the roof of 25 pounds per square foot

Minnesota State Building Code
Beginning June 1, 2009, Minnesota’s Energy Code is based on ASHRAE Standard 90.1 – 2004. This increases the minimum levels of insulation on most roof assemblies. Commercial roofs with continuous layers of insulation above deck will now be required to have an R value of 23.0.

City of Chicago Building Code
Chicago has embraced energy efficiency and has made cool roofing for low sloped roofs the prescriptive standard. There are exceptions for:

• Green roofing (must cover 33% of roof surface)
• Roofs with solar photovoltaic or solar thermal
• Gravel surface ballasted roofs (ballast weight must be greater than 15 psf)
• Built-up roofing with gravel (not more than 5% of black material showing)

The 2009 International Building Code (IBC) is in print, and states and local governments will begin the process of adopting and amending this model code to suit their local needs. Scanning the list of code adoptions, the version of IBC could be 2000, 2003, or 2006, depending on where your project is.

Ozone Transport Commission
The OTC is an organization of 13 Northeastern and Mid-Atlantic States whose mission is to develop rules to reduce the formation of ozone or smog to meet EPA requirements.

One of the contributors to ozone is volatile organic compounds or VOC’s. The roofing industry commonly uses adhesives, primers, coatings, and sealants that are VOC’s. The OTC Model Rule regulates the seasonal use of certain VOC’s, with the intent of eliminating these products by 2012. In the meantime, restrictions on the use of VOC products are in place for 2009 to 2011 for Connecticut, Washington D.C., Maryland, New Jersey, and Rhode Island (at the time of this writing). Briefly, solvent-based bonding adhesives, roof cements, primers, and the like will not be able to be used in June through August in 2009, and May through September in 2010 and 2011. This phasing-in of the restrictions is intended to allow the manufacturers to develop VOC-compliant alternatives.

Some VOC substitutes now exist, but are mostly water-based products that cannot be used below 40 degrees F. VOC-compliant components are also likely more expensive than their non-compliant counterparts. This will cause heartburn in those areas that adopt the OTC Model Rule.

Other Standards
Many areas of the building code refer to consensus standards, such as ANSI or ASTM. The Single Ply Roofing Institute (SPRI) is one of the promulgators of roofing standards, where its membership recognizes the need to fill the gap between the building code’s language and available design and testing standards. Currently, SPRI is working on revisions to:

ANSI/SPRI RD-1   Roof drain standard
ANSI/SPRI ES-1    Edge metal standard
                       (IBC code requirement)

In addition, SPRI is working on these new roofing standards:

GD-1   Gutter Design Standard
VF-1    Vegetative Roof Fire Standard
RP-14  Vegetative Roof Wind Standard
VR-1    Vegetative Roof Barrier Standard

The last three are all related to vegetative roofing, and are intended to provide guidance for the safe and proper design of these systems.

Conclusion
I can think of no other construction trade that has the level of product innovation and change than that which is present in the field of commercial low-slope roofing. Designers need to stay current with this innovation and change by studying and understanding the standards. Finally, the designer must distill these standards and make them part of a cohesive, constructible, and code-compliant roof design.

[Reprinted from Benchmark Perspectives, Volume 64: May 2009.]