IBC Chapter 14 provides general product and installation requirements for cladding in multifamily and commercial use.
Product Requirements (1403)
Products must be certified and labeled to show they conform to their established ASTM standard:
Insulated vinyl siding is not addressed in the 2021 IBC, however it was added to the 2024 IBC. Building officials may rely on code compliance reports for verification based on the established standard for the product category, ASTM D7793.
Insulated Vinyl Siding
ASTM D7793—Code Compliance Reports
Table 1404.3(3) counts vinyl siding and polypropylene siding as vented claddings and allows the elimination of vapor retarders because of its strong moisture management characteristics.
In general, vinyl siding and insulated vinyl siding are installed 16" on center using roofing nails, although variations can be done including other approved fasteners like staples and screws. Prescriptive requirements for vinyl siding installation include that non-corrosive roofing nails that can penetrate the nailable substrate at least 1 1/4" must be spaced no more than 16" for horizontal siding and 12" for vertical siding and according to the manufactured installation instructions. (IBC 1404.14)
Polypropylene siding panels range in size and are unique. Manufacturer’s installation instructions should be reviewed because in many cases it may be less than 16" on center. It must be installed over some type of wood sheathing.
When installing polypropylene siding in high-density settings (less than 5 feet to property line), the product must have a certified E84 test report.
Considerations and Conditions for use in High-density Developments with Noncombustible Construction
In general, polymeric cladding is allowed in all types of construction, including noncombustible construction. If the polymeric cladding is used with noncombustible construction, certain test results are demonstrated according to 1405.
Specific information on the use of insulated vinyl siding will be listed in the code compliance report.
Table 601 and 705.5 place certain fire resistance ratings on walls depending on the occupancy, type, density (distance to lot line) and size of the building based on ASTM E119 tests.
Polymeric cladding is a part of many E119-rated assemblies. In addition, vinyl siding specifically is allowed to be part of 722’s calculated fire resistance approach through Table 722.6.2(3).
1405 provides the use of polymeric cladding (and other combustible cladding) with noncombustible construction (Types I, II, III, IV).
If polymeric cladding is used with noncombustible construction (Types I, II, III, IV) it must be tested according to NFPA 268 (1405.1) and perform to certain levels depending on the building’s fire separation distance. This test method demonstrates the ability of other combustible materials to not ignite under certain radiant heat conditions.
Code at a Glance
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