SpecTopics: Re-roofing and Structural Concerns

Do Building Codes Require Structural Enhancement for Re-roofing Work?

Today’s re-roofing market is going strong, with 62% of roofing work versus 38% for new construction. While most specifiers and roofers know the requirements for re-roofing to meet current building and energy code, there is always a level of uncertainty when it comes to the structure of the roof itself. Can I tear off the old roof and start my new roof application with the existing deck? Or is something more required?

Re-roofing work which consists of a complete tear-off is considered an Alteration – Level 1 for the International Existing Building Code (IEBC) 2018 and 2021 editions. In Chapter 5, an Alteration Level 1 is described as “includes the removal and replacement or the covering of existing materials, elements, equipment, or fixtures using new materials, elements, equipment, or fixtures that serve the same purpose.”

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Descriptions for the code requirements for Alteration – Level 1 are in Chapter 7 and include Section 706 – Structural, which describes two additional structural requirements for roof replacement:

1. (706.3.1) Where the re-roofing work is more than 25% of the roof area, and the building is assigned a seismic design category of D, E, or F (Chapter 20 of ASCE 7), unreinforced masonry wall parapets must be braced according to 301.1.4.2 of the International Building Code (IBC).
2. (706.3.2) If the existing roofing system is removed and the deck is exposed for more than 50% of the roof area and the building is located where the ultimate design wind speed is greater than 115 mph OR the project is located in a special wind region, all structural roof connections must be evaluated for the wind uplift and if unable to support 75% of the wind load, they must be strengthened or replaced as defined in Chapter 16 of the IBC.

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These requirements will not affect all buildings. Checking with a structural engineer for determining the existing building’s seismic design category or evaluating wind uplift potential of existing structural components will add cost to the project. Additionally, more cost could be added if structural remediation is required.

Always check with the Authority Having Jurisdiction (AHJ) for local requirements before proceeding with re-roofing work. Contact Craig Tyler at with further questions.