Today’s re-roofing market is going strong, making up 62% of all roofing work versus 38% for new construction. While most specifiers and roofers know the requirements for re-roofing to meet current building and energy codes, 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 consisting of a complete tear-off is considered an Alteration – Level 1 for the International Existing Building Code (IEBC) 2015 and 2018 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”.
Descriptions of the code requirements for Alteration – Level 1 are in Chapter 7 and include Section 707 – Structural, which describes two additional structural requirements for roof replacement:
1. (707.3.1) 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. (707.3.2) 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.
These requirements will not affect all buildings. Checking with a structural engineer to determine the existing building’s seismic design category or evaluating wind uplift potential of existing structural components will increase the project’s cost. Additionally, more costs 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 [email protected]