Section 2508 — GYPSUM CONSTRUCTION — 2025 California Building Code (Title 24, Part 2)

2508.1 General. ¶

2508.1 General. Gypsum panel products and gypsum plaster construction shall be of the materials listed in Tables 2506.2 and 2507.2. These materials shall be assembled and installed in compliance with the appropriate standards listed in Tables 2508.1 and 2511.1.1 and Chapter 35. TABLE 2508.1—INSTALLATION OF GYPSUM CONSTRUCTIONCol2 ------ MATERIALSTANDARD Gypsum panel productsGA-216; ASTM C840 Gypsum sheathing and gypsum panel productsASTM C1280; GA-253 Gypsum veneer baseASTM C844 Interior lathing and furringASTM C841 Steel framing for gypsum panel productsASTM C754; C1007

provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling

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2508.2 Limitations. ¶

2508.2 Limitations. Gypsum wallboard or gypsum plaster shall not be used in any exterior surface where such gypsum construction will be exposed directly to the weather. Gypsum wallboard shall not be used where there will be direct exposure to water or continuous high humidity conditions. Gypsum sheathing shall be installed on exterior surfaces in accordance with ASTM C1280 or GA-253. 2508.2.1 Weather protection. Gypsum wallboard, gypsum lath or gypsum plaster shall not be installed until weather protection for the installation is provided.

provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot

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2508.3 Single-ply application. ¶

2508.3 Single-ply application. Edges and ends of gypsum panel products shall occur on the framing members, except those edges and ends that are perpendicular to the framing members. Edges and ends of gypsum panel products shall be in moderate contact except in concealed spaces where fire-resistance-rated construction, shear resistance or diaphragm action is not required. 2508.3.1 Floating angles. Fasteners at the top and bottom plates of vertical assemblies, or the edges and ends of horizontal assemblies perpendicular to supports, and at the wall line are permitted to be omitted except on…

provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted

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2508.4 Adhesives. ¶

2508.4 Adhesives. Gypsum panel products secured to framing with adhesives in ceiling assemblies shall be attached using an approved fastening schedule. Expandable foam adhesives for fastening gypsum wallboard shall conform to ASTM D6464. Other adhesives for the installation of gypsum wallboard shall conform to ASTM C557.

provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision

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2508.5 Joint treatment. ¶

2508.5 Joint treatment. Gypsum panel product fire-resistance-rated assemblies shall have joints and fasteners treated. Exceptions: Joint and fastener treatment need not be provided where any of the following conditions occur: 1. Where the gypsum panel product is to receive a decorative finish such as wood paneling, battens, acoustical finishes or any similar application that would be equivalent to joint treatment. 2. On single-layer systems where joints occur over wood framing members. 3. Square edge or tongue-and-groove edge gypsum board (V-edge), gypsum panel products, gypsum backing board…

provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance

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2508.6 Horizontal gypsum panel product diaphragm ceilings. ¶

2508.6 Horizontal gypsum panel product diaphragm ceilings. Gypsum panel products shall be permitted to be used on wood joists to create a horizontal diaphragm ceiling in accordance with Table 2508.6. 25-6 2025 CALIFORNIA BUILDING CODE on Jul 18, 2025 11:14 AM (CDT) THEREUNDER. GYPSUM PANEL PRODUCTS AND PLASTER TABLE 2508.6—SHEAR CAPACITY FOR HORIZONTAL WOOD-FRAME GYPSUM PANEL PRODUCT DIAPHRAGM CEILING ASSEMBLIESCol2Col3Col4Col5 --------------- MATERIALTHICKNESS OF<brMATERIAL<br(MINIMUM) (inches)SPACING OF<brFRAMING MEMBERS<br(inches)SHEAR VALUEa, b <br(PLF OF CEILING)MIMIMUM FASTENER SIZE…

provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use provision permitted lot commission district approval parking minimum height dwelling application requirement review coverage subject setback occupancy development standard accessory yard section structure compliance use

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