International Building Code (IBC) Chapter 15

The International Building Code (IBC) is a model building code published by the International Code Council (ICC), a US non-profit formed in 1994 by merging three regional code bodies (BOCA, ICBO and SBCCI). The first IBC was published in 2000, and new editions follow every three years (2003, 2006 ... 2021, 2024). Most US states and many local governments adopt it, often with amendments. It is also used or adapted in some other countries and territories.

The IBC covers all buildings except detached one- and two-family dwellings and small townhouses, which fall under the International Residential Code.

Chapter 15: Roof Assemblies and Rooftop Structures

Roofing rules sit mainly in Chapter 15. In the 2024 edition its sections include general provisions, roof drainage, weather protection (flashing, coping, crickets), performance requirements, fire classification, materials, requirements for each type of roof covering, insulation, reroofing and rooftop structures.

Key topics include:

• Performance requirements (Section 1504). Roof coverings must resist wind. Membrane roofs must be tested to UL 580, UL 1897 or FM 4474; metal panel roofs to UL 580 or equivalent. Asphalt shingles must be wind-classified under ASTM D7158 or ASTM D3161.
• Fire classification. Roofs are classified Class A, B or C under ASTM E108 or UL 790, with the required class depending on construction type and location.
• Roof coverings. Separate requirements apply to asphalt shingles, clay and concrete tile, metal panels and shingles, slate, wood shingles and shakes, built-up, modified bitumen, single-ply membranes, sprayed foam, liquid-applied coatings and photovoltaic systems. These specify minimum slopes, underlayment, fastening and referenced product standards such as ASTM D3462.
• Reroofing. Rules on when an existing roof must be removed, how many layers are allowed, and when recovering is permitted.

Related chapters

Structural loads on roofs (dead, live, snow, wind, rain) are in Chapter 16, which references ASCE 7. Energy requirements for roof insulation come from the International Energy Conservation Code or ASHRAE 90.1. Some states, notably Florida, publish their own code based on the IBC with additional hurricane provisions.

Using the code

Because the IBC is a model code, the edition and amendments in force vary by jurisdiction. Roofers and designers must check which edition the local authority has adopted.