Because of our current litigious environment, many roofing professionals are careful to follow building code requirements exactly lest they face legal challenges. However, there may be instances when strictly adhering to the prescriptive code without engineering analysis and evaluation does more harm than good.
For example, the 2006 International Building Code's® (IBC's) roof ventilation requirements do not distinguish between low- and steep-slope roof assemblies. In fact, the language suggests the ventilation requirements are for steep-slope assemblies only. However, some roof system designers and code officials have interpreted the code literally and designed or required roof ventilation systems for low-slope assemblies, which can be more deleterious than beneficial.
2006 prescriptive requirement
Roofing professionals who look to IBC 2006 for ventilation requirements for low-slope roof assemblies will find Chapter 15, Roof Assemblies and Rooftop Structures, Section 1503 Weather Protection, 1503.5 Roof Ventilation, which reads: "1503.5 Roof ventilation. Intake and exhaust vents shall be provided in accordance with Section 1203.2 and the manufacturer's installation instructions."