What’s required for my unfinished ICF basement?

The BuildBlock Intertek IRR1003, requires a 15 minute fire barrier for all EPS that is exposed to the interior of the building. This can be drywall, which is typically the most cost effective method, stucco, plaster, EIFS, wood paneling, or any other finish product with a 15 minute fire rating.

A stem wall or any other ICF wall below grade would not require anything as it is below a slab, however any area that is used for living space, storage, as an air transfer with the home, or is planned to be anything more than utility access, requires a 15 minute fire barrier.

 From the BuildBlock IRR1003 Code Approval Report

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4.3 Interior Finish

4.3.1 General: ICF units exposed to the building interior must be finished with an approved 15-minute thermal barrier, such as minimum ½ inch thick (12.7 mm) regular gypsum wallboard complying with ASTM C1396, installed vertically and attached to the cross-tie flanges with minimum 15/8 inch long (41 mm), No. 6, Type W, coarse-thread gypsum wallboard screws spaced 16 inches (406 mm) on center vertically and 12 inches (305 mm) on center horizontally. The screws must penetrate a minimum of ¼ inch through the flange. Gypsum board joints and screw heads must be taped and finished with joint compound in accordance with ASTM C840 or GA216. See Section 4.3.2 for installation details for crawl space applications without an ignition barrier on the interior face.

4.3.2 Attic and Crawl Space Installations: When the ICFs are used for walls of attic or crawl spaces, an ignition barrier complying with IBC Section 2603.4.1.6, or IRC Sections R316.5.3 or R316.5.4, is required, except when all of the following conditions are met: Entry to the attic or crawl space is only to service utilities, and no storage is permitted.

• There are no interconnected attic or basement areas.
• Air in the attic or crawl space is not circulated to other parts of the building.
• Under-floor (crawl space) ventilation is provided that complies with IBC Sections 1203.3 or IRC Section R408.1, as applicable.
• Attic ventilation is provided when required by IBC Section 1203.2 or IRC Section R806, as applicable.
• Combustion air is provided in accordance with IMC (International Mechanical Code) Section 701.
• The ICFs must have at least one label as described in Section 7.0 visible in every 160 square feet (15 m2) of wall area.

Read the full BuildBlock Installation & Technical Manual here.

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