Specific building code requirements apply to roof system re-cover and replacement projects. But because a large number of reroofing and re-cover projects are undertaken without a licensed design professional's involvement, it is important you know building code requirements that apply to such projects.
In the International Building Code, 2012 Edition (IBC 2012) and its previous editions, roof systems are addressed in Chapter 15Roof Assemblies and Rooftop Structures. Requirements for reroofing specifically are addressed in Section 1510Reroofing.
IBC 2012's Section 1510.1General indicates materials and application methods used for re-covering or replacing existing roof systems must comply with the same requirements as new roof systems except reroofing projects need not comply with the code's minimum 1/4:12 slope requirement for roofs that provide positive drainage. The code defines positive drainage as a condition in which consideration has been made for all loading deflections of a roof deck and additional slope has been provided to ensure roof drainage within 48 hours of precipitation.