Chapter 44 — REFERENCED STANDARDS
Section BE103 — REQUIREMENTS
2025 California Residential Code (Title 24, Part 2.5) · 2025 edition · ingested 2026-07-07 · California
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BE103.1 General. ¶
BE103.1 General. The following construction techniques are intended to resist radon entry and prepare the building for postconstruction radon mitigation, if necessary (see Figure BE103.1). These techniques are required in areas where designated by the jurisdiction. APPENDIX BE-4 2025 CALIFORNIA RESIDENTIAL CODE on Jul 18, 2025 11:14 AM (CDT) THEREUNDER. APPENDIX BE — RADON CONTROL METHODS TABLE BE101.1—HIGH RADON-POTENTIAL (ZONE 1) COUNTIES [a] on Jul 18, 2025 11:14 AM (CDT) THEREUNDER. APPENDIX BE — RADON CONTROL METHODS TABLE BE101.1—HIGH RADON-POTENTIAL (ZONE 1) COUNTIES [a] —continued…
BE103.2 Subfloor preparation. ¶
BE103.2 Subfloor preparation. A layer of gas-permeable material shall be placed under all concrete slabs and other floor systems that directly contact the ground and are within the walls of the living spaces of the building, to facilitate future installation of a subslab depressurization system, if needed. The gas-permeable layer shall consist of one of the following: 1. A uniform layer of clean aggregate, not less than 4 inches (102 mm) thick. The aggregate shall consist of material that will pass through a 2-inch (51 mm) sieve and be retained by a [1] / 4 -inch (6.4 mm) sieve. 2. A uniform…
BE103.3 Soil-gas-retarder. ¶
BE103.3 Soil-gas-retarder. Flexible sheeting material complying with Section R506.3.3 shall be placed on top of the gas-permeable layer prior to casting the slab or placing the floor assembly to serve as a soil-gas-retarder by bridging any cracks that develop in the slab or floor assembly, and to prevent concrete from entering the void spaces in the aggregate base material. The sheeting shall cover the entire floor area with separate sections of sheeting lapped not less than 12 inches (305 mm). The sheeting shall fit closely around any pipe, wire or other penetrations of the material.…
BE103.4 Entry routes. ¶
BE103.4 Entry routes. Potential radon entry routes shall be closed in accordance with Sections BE103.4.1 through BE103.4.10. on Jul 18, 2025 11:14 AM (CDT) THEREUNDER. APPENDIX BE — RADON CONTROL METHODS BE103.4.1 Floor openings. Openings around bathtubs, showers, water closets, pipes, wires or other objects that penetrate concrete slabs, or other floor assemblies, shall be filled with a polyurethane caulk or equivalent sealant applied in accordance with the manufacturer’s recommendations. BE103.4.2 Concrete joints. Control joints, isolation joints, construction joints, and any other joints…
BE103.5 Passive submembrane depressurization system. ¶
BE103.5 Passive submembrane depressurization system. In buildings with crawl space foundations, the following components of a passive submembrane depressurization system shall be installed during construction. Exception: Buildings in which an approved mechanical crawl space ventilation system or other equivalent system is installed. BE103.5.1 Ventilation. Crawl spaces shall be provided with vents to the exterior of the building. The minimum net area of ventilation openings shall comply with Section R408.1. BE103.5.2 Soil-gas-retarder. The soil in crawl spaces shall be covered with a…
BE103.6 Passive subslab depressurization system. ¶
BE103.6 Passive subslab depressurization system. In basement or slab-on-grade buildings, the following components of a passive subslab depressurization system shall be installed during construction. BE103.6.1 Vent pipe. A minimum 3-inch-diameter (76 mm) ABS, PVC or equivalent gastight pipe shall be embedded vertically into the subslab aggregate or other permeable material before the slab is cast. A “T” fitting or equivalent method shall be used to ensure that the pipe opening remains within the subslab permeable material. Alternatively, the 3-inch (76 mm) pipe shall be inserted directly into…
BE103.7 Vent pipe drainage. ¶
BE103.7 Vent pipe drainage. Components of the radon vent pipe system shall be installed to provide positive drainage to the ground beneath the slab or soil-gas-retarder.
BE103.8 Vent pipe accessibility. ¶
BE103.8 Vent pipe accessibility. Radon vent pipes shall be accessible for future fan installation through an attic or other area outside the habitable space. Exception: The radon vent pipe need not be accessible in an attic space where an approved roof-top electrical supply is provided for future use.
BE103.9 Vent pipe identification. ¶
BE103.9 Vent pipe identification. Exposed and visible interior radon vent pipes shall be identified with not less than one label on each floor and in accessible attics. The label shall read: “Radon Reduction System.”
BE103.10 Combination foundations. ¶
BE103.10 Combination foundations. Combination basement/crawl space or slab-on-grade/crawl space foundations shall have separate radon vent pipes installed in each type of foundation area. Each radon vent pipe shall terminate above the roof or shall be connected to a single vent that terminates above the roof.
BE103.11 Building depressurization. ¶
BE103.11 Building depressurization. Joints in air ducts and plenums in unconditioned spaces shall meet the requirements of Section M1601. Thermal envelope air infiltration requirements shall comply with the energy conservation provisions in Chapter 11. Fireblocking shall meet the requirements contained in Section R302.11.
BE103.12 Power source. ¶
BE103.12 Power source. To provide for future installation of an active submembrane or subslab depressurization system, an electrical circuit terminated in an approved box shall be installed during construction in the attic or other anticipated location of vent pipe fans. An electrical supply shall be accessible in anticipated locations of system failure alarms.