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Reroofing and code compliance

Reroofing existing buildings presents unique and increasingly complex challenges relating to code compliance. Although a building being reroofed may have been constructed according to the code applicable during original construction, reroofing projects typically trigger at least a partial upgrade to the currently applicable code(s). Scope and applicability Model building codes, including the International Building Code (IBC) and International Residential Code (IRC), are developed and maintained with the general intent of applying to buildings at the time of original construction. One exception is IBC and IRC also address reroofing— re-covering and replacing existing roof coverings on existing buildings. In IBC 2015, roof assemblies are addressed in Chapter 15— Roof Assemblies and Rooftop Structures. Within IBC 2015, Chapter 15, Section 1511—Reroofing addresses reroofing. Previous editions of IBC addressed reroofing in Section 1510—Reroofing. The addition of a new section in IBC 2015 addressing radiant barriers above roof decks resulted in renumbering IBC 2015’s subsequent Chapter 15 sections. Also, IBC 2015’s Section 1511—Reroofing is reformatted from previous IBC editions; however, reroofing requirements are generally similar among the various editions. In IRC 2015 and its previous editions, roof assemblies are addressed in Chapter 9—Roof Assemblies. Within IRC’s Chapter 9, Section R908—Reroofing addresses reroofing. IRC’s reroofing requirements generally are consistent with those of the same edition of IBC. Reroofing requirements IBC 2015’s Section 1511.1—General indicates: “Materials and methods of application used for recovering or replacing an existing roof covering shall comply with the requirements of Chapter 15.” This statement generally is interpreted to indicate that during reroofing operations, the new roof system itself needs to comply with the currently adopted code edition. However, other roof assembly components, such as the roof deck and attic ventilation, generally are not required as part of a typical reroofing project to be upgraded to the currently adopted code edition. There are two notable exceptions to IBC 2015’s Section 1511.1. In the first exception, roof coverings installed in roof system replacement and roof re-covering projects are not required to comply with the code’s ¼-inch-per-foot minimum slope requirement for new construction projects provided the roof system allows for positive drainage. The code defines the term “positive drainage” similarly to NRCA, providing for drainage of the roof within 48 hours of precipitation. A second exception applies to existing buildings that do not have secondary roof drainage provisions, such as overflow drains and overflow scuppers. In these instances, new secondary drainage does not need to be installed if the existing roof system provides for positive drainage. IBC’s secondary roof drainage requirement first was added in IBC 2009; secondary drainage was not required with IBC’s previous editions. Using IBC 2009 or IBC 2012, it could be interpreted the addition of secondary drainage may be required during reroofing—this was not the intent of the 2009 code change. IBC 2015’s Section 1511.3—Roof Replacement addresses when roof system replacement (tear-off) is s exist: • The existing roof has two or more applications of any type of roof covering. • The existing roof is water-soaked or deteriorated to the point it will not provide an adequate substrate for roof re-covering. • The existing roof covering is slate, clay, cement or asbestoscement tile. Where the code requires roof replacement, tear-off of all layers of roofing down to the deck is required. Peeling off the topmost roof layer and re-covering an underlying roof layer is not permitted. When the existing roof assembly includes an existing ice dam protection membrane, the existing ice dam protection membrane is permitted to remain in place provided it is covered with an additional layer of ice dam protection. IRC 2015’s requirements for reroofing generally are the same as IBC 2015’s requirements. Two legacy model building codes (Building Officials and Code Administrators National Building Code and Standard [Southern] Building Code), IBC 2000 and IRC 2000 contained a provision This provision exempted reroofing projects limited to 25 percent or less of a building’s roof area from needing to comply with the currently applicable code’s reroofing requirements. It is important to note this provision was removed in IBC 2003, IRC 2003 and subsequent editions and no longer applies to reroofing. It generally is interpreted any roof system replacement or roof re-covering project regardless of its size or scope now is required to comply with the code’s reroofing requirements. Roof repairs (small patches) typically are interpreted as being exempt for code upgrades provided the repair is of like material and application method to the surface being repaired.

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