When Codes are in Conflict: Building Science and Life Safety in Wood Framed Construction

Over time, changes in building codes have begun to challenge designers to meet life safety, indoor air quality, and energy efficiency requirements on wood-framed, mid-rise multi-family projects. When NFPA 13 sprinkler requirements are driving the design of the roof assembly, the risk of condensation often increases: While vented roof assemblies are effective in steep slope applications, the thermodynamics of a vented low-slope roof assembly make condensation more likely. To combat this many designers opt to provide a non-vented assembly with rigid insulation above the roof deck. This approach will generally trigger NFPA 13 sprinkler requirements which many developers and general contractors attempt to side-step by filling the roof cavity with a non-combustible insulation. The additional insulation within the framing requires careful consideration of vapor control strategies. It is critical for enclosure consultants to understand the code requirements that pertain to Type V construction and be able to identify the risks associated with the various compliance paths. In this presentation we will examine the various paths to code compliance while still applying building science principles to limit condensation risk. Detailed roof system examples will be provided, demonstrating how these measures can enable durable AND code compliant roofing assemblies.

Learning Objectives:

1.  Knowledge of code changes and how they impact durability in roofing assemblies.
2.  How to choose a vapor control strategy that meets the code requirements for life safety, indoor air quality, and energy efficiency.
3.  The impact of value engineering decisions related to sprinklers on roof performance.
4.  How hygrothermal modeling can inform the amount, type, and placement of insulation in a roof assembly.

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Erin Andes, PE (CA, WY), LEED AP, Director of Design Outreach, GAF

 As the Director of Design Outreach for the GAF Building and Roofing Science Team, Erin works with designers to review project designs to mitigate risk and achieve affordable, durable, watertight, and energy-efficient roof assemblies. In addition to helping design teams with roof assemblies and details, she regularly presents and publishes technical content related to building and roofing science at conferences and training events. Her background includes building enclosure consulting on new construction and enclosure rehabilitation of a range of project types such as multi-family, commercial, institutional, religious, cultural, and healthcare buildings. In addition, Erin has provided investigation and litigation support services on building enclosure and product failures giving her great perspective on what to avoid in new construction and repairs.