Adopting agency | BSC | BSC-CG | SFM | HCD | DSA | OSHPD | BSCC | DPH | AGR | DWR | CEC | CA | SL | SLC | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 1/AC | AC | SS | SS/CC | 1 | 1R | 2 | 3 | 4 | 5 | ||||||||||||
Adopt entire chapter | X | X | X | ||||||||||||||||||||
Adopt entire chapter as amended (amended sections listed below) | X | X | X | X | X | X | X | ||||||||||||||||
Adopt only those sections that are listed below | |||||||||||||||||||||||
Chapter / Section | |||||||||||||||||||||||
2501.1.1 | X | X | X | X | X | X | X | ||||||||||||||||
2501.1.2 | X | X | X | X | X | X | X | ||||||||||||||||
2501.1.3 | X | X | X | X | X | X | X | ||||||||||||||||
2503.2 | X | X | X | X | X | X | X | ||||||||||||||||
2503.2, Exception | X | ||||||||||||||||||||||
2504.2 | X | X | X | X | X | X | X | ||||||||||||||||
2504.2.1, Exception | X | ||||||||||||||||||||||
2505.3 | X | X | X | X | X | X | X | ||||||||||||||||
2505.3, Exception | X | ||||||||||||||||||||||
2507.3 | X | X | X | X | X | X | X | ||||||||||||||||
2507.3, Exception | X | ||||||||||||||||||||||
2508.6.6 | X | X | X | X | X | X | X | ||||||||||||||||
2508.6.6, Exception | X | ||||||||||||||||||||||
2514.1 Exception | X | X | X | X | X | X | |||||||||||||||||
The Office of the State Fire Marshal's adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
User notes:
About this chapter: Chapter 25 contains the provisions and referenced standards that regulate the design, construction and quality of gypsum board, gypsum panel products and plaster and, in addition, addresses reinforced gypsum concrete. These materials are some of the most commonly used interior and exterior finish materials in the building industry. This chapter primarily addresses quality-control-related issues with regard to material specifications and installation requirements. Most products are manufactured in accordance with industry standards. The building official or inspector needs to verify that the appropriate product is used and properly installed for the intended use and location. Proper design and installation of these materials are necessary to provide weather resistance and required fire protection for both structural and nonstructural building components.
Code development reminder: Code change proposals to this chapter will be considered by the IBC—Structural Code Development Committee during the 2019 (Group B) Code Development Cycle. See explanation on page ix.
- Applications listed in Sections 1.10.1, 1.10.2, 1.10.4 and 1.10.5 regulated by the Office of Statewide Health Planning and Development (OSHPD). These applications include hospitals, hospital buildings removed from general acute care service, skilled nursing facility buildings, intermediate care facility buildings, correctional treatment centers and acute psychiatric hospital buildings.
- Structures regulated by the Division of the State Architect—Structural Safety, which include those applications listed in Section 1.9.2.1 (DSA-SS), and 1.9.2.2 (DSA-SS/CC). These applications include public elementary and secondary schools, community colleges and state-owned or state-leased essential services buildings
- OSHPD amendments appear in this chapter preceded with the appropriate acronym, as follows:
[OSHPD 1] - For applications listed in Section 1.10.1.
[OSHPD 1R] - For applications listed in Section 1.10.1.
[OSHPD 2] - For applications listed in Section 1.10.2.
[OSHPD 4] - For applications listed in Section 1.10.4.
[OSHPD 5] - For applications listed in Section 1.10.5. - Division of the State Architect - Structural Safety:
[DSA-SS] - For applications listed in Section 1.9.2.1.
[DSA-SS/CC] - For applications listed in Section 1.9.2.2.
Other approved wall or ceiling coverings shall be permitted to be installed in accordance with the recommendations of the manufacturer and the conditions of approval.
- Lath, gypsum board and gypsum panel products shall be inspected in accordance with Chapter 17A and the California Administrative Code.
- No lath, gypsum board and gypsum panel products or their attachments shall be covered or finished until it has been inspected and approved by the inspector of record and/or special inspector.
- The enforcement agency may require tests in accordance with Table 2506.2 to determine compliance with the provisions of this code.
- The testing of gypsum board and gypsum panel products shall conform with standards listed in Table 2506.2
Wood supports for lath, gypsum board or gypsum panel products, as well as wood stripping or furring, shall be not less than 2 inches (51 mm) nominal thickness in the least dimension.
Exception: The minimum nominal dimension of wood furring strips installed over solid backing shall be not less than 1 inch by 2 inches (25 mm by 51 mm).
Where common wire nails are used to support horizontal wood stripping for plaster ceilings, such stripping shall be wire tied to the joists 4 feet (1219 mm) on center with two strands of No. 18 W&M gage galvanized annealed wire to an 8d common wire nail driven into each side of the joist 2 inches (51 mm) above the bottom of the joist or to each end of a 16d common wire nail driven horizontally through the joist 2 inches (51 mm) above the bottom of the joist, and the ends of the wire secured together with three twists of the wire.
Gypsum board and gypsum panel products shall conform to the appropriate standards listed in Table 2506.2 and Chapter 35 and, where required for fire protection, shall conform to the provisions of Chapter 7.
GYPSUM BOARD AND GYPSUM PANEL PRODUCTS MATERIALS AND ACCESSORIES
MATERIAL | STANDARD |
Accessories for gypsum board | ASTM C1047 |
Adhesives for fastening gypsum board | ASTM C557 |
Cold-formed steel studs and track, structural | AISI S240 |
Cold-formed steel studs and track, nonstructural | AISI S220 |
Elastomeric joint sealants | ASTM C920 |
Expandable foam adhesives for fastening gypsum wallboard | ASTM D6464 |
Factory-laminated gypsum panel products | ASTM C1766 |
Fiber-reinforced gypsum panels | ASTM C1278 |
Glass mat gypsum backing panel | ASTM C1178 |
Glass mat gypsum panel 5 | ASTM C1658 |
Glass mat gypsum substrate | ASTM C1177 |
Joint reinforcing tape and compound | ASTM C474; C475 |
Nails for gypsum boards | ASTM C514, F547, F1667 |
Steel screws | ASTM C954; C1002 |
Standard specification for gypsum board | ASTM C1396 |
Testing gypsum and gypsum products | ASTM C22; C472; C473 |
Lathing and plastering materials shall conform to the standards listed in Table 2507.2 and Chapter 35 and, where required for fire protection, shall conform to the provisions of Chapter 7.
LATH, PLASTERING MATERIALS AND ACCESSORIES
MATERIAL | STANDARD |
Accessories for gypsum veneer base | ASTM C1047 |
Blended cement | ASTM C595 |
Cold-formed steel studs and track, structural | AISI S240 |
Cold-formed steel studs and track, nonstructural | AISI S220 |
Exterior plaster bonding compounds | ASTM C932 |
Hydraulic cement | ASTM C1157; C1600 |
Gypsum casting and molding plaster | ASTM C59 |
Gypsum Keene's cement | ASTM C61 |
Gypsum plaster | ASTM C28 |
Gypsum veneer plaster | ASTM C587 |
Interior bonding compounds, gypsum | ASTM C631 |
Lime plasters | ASTM C5; C206 |
Masonry cement | ASTM C91 |
Metal lath | ASTM C847 |
Plaster aggregates Sand Perlite | ASTM C35; C897 ASTM C35 ASTM C35 |
Plastic cement | ASTM C1328 |
Portland cement | ASTM C150 |
Steel screws | ASTM C1002; C954 |
Welded wire lath | ASTM C933 |
Woven wire plaster base | ASTM C1032 |
- Secure lath to alternate supports with ties consisting of a double strand of No. 18 W & M gage galvanized annealed wire at one edge of each sheet of lath. Wire ties shall be installed not less than 3 inches (76 mm) back from the edge of each sheet and shall be looped around stripping, or attached to an 8d common wire nail driven into each side of the joist 2 inches (51 mm) above the bottom of the joist or to each end of a 16d common wire nail driven horizontally through the joist 2 inches (51 mm) above the bottom of the joist and the ends of the wire secured together with three twists of the wire.
- Secure lath to each support with 1/2-inch-wide (12.7 mm), 11/2-inch-long (38mm) No. 9 W & M gage, ring shank, hook staple placed around a 10d common nail laid flat under the surface of the lath not more than 3 inches (76 mm) from edge of each sheet. Such staples may be placed over ribs of 3/8-inch (9.5 mm) rib lath or over back wire of welded wire fabric or other approved lath, omitting the 10d nails.
Gypsum board, 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.
INSTALLATION OF GYPSUM CONSTRUCTION
MATERIAL | STANDARD |
Gypsum board and gypsum panel products | GA-216; ASTM C840 |
Gypsum sheathing and gypsum panel products | ASTM C1280 |
Gypsum veneer base | ASTM C844 |
Interior lathing and furring | ASTM C841 |
Steel framing for gypsum board and gypsum panel products | ASTM C754; C1007 |
Gypsum board and gypsum panel product fire-resistance-rated assemblies shall have joints and fasteners treated.
Exception: Joint and fastener treatment need not be provided where any of the following conditions occur:
- Where the gypsum board or 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.
- On single-layer systems where joints occur over wood framing members.
- Square edge or tongue-and-groove edge gypsum board (V-edge), gypsum panel products, gypsum backing board or gypsum sheathing.
- On multilayer systems where the joints of adjacent layers are offset.
- Assemblies tested without joint treatment.
Gypsum board or gypsum panel products shall be permitted to be used on wood joists to create a horizontal diaphragm ceiling in accordance with Table 2508.6.
SHEAR CAPACITY FOR HORIZONTAL WOOD-FRAME GYPSUM BOARD DIAPHRAGM CEILING ASSEMBLIES
MATERIAL | THICKNESS OF MATERIAL (MINIMUM) (inches) | SPACING OF FRAMING MEMBERS (inches) | SHEAR VALUEa, b (PLF OF CEILING) | MIMIMUM FASTENER SIZE |
Gypsum board or gypsum panel product | 1/2 | 16 o.c. | 90 | 5d cooler or wallboard nail; 15/8-inch long; 0.086-inch shank; 15/64-inch headc |
Gypsum board or gypsum panel product | 1/2 | 24 o.c. | 70 | 5d cooler or wallboard nail; 15/8-inch long; 0.086-inch shank; 15/64-inch headc |
For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.59 N/m.
- Values are not cumulative with other horizontal diaphragm values and are for short-term wind or seismic loading. Values shall be reduced 25 percent for normal loading.
- Values shall be reduced 50 percent in Seismic Design Categories D, E and F.
- 11/4-inch, No. 6 Type S or W screws are permitted to be substituted for the listed nails.
Materials used as a base for wall tile in tub and shower areas and wall and ceiling panels in shower areas shall be of materials listed in Table 2509.2 and installed in accordance with the manufacturer's recommendations. Water-resistant gypsum backing board shall be used as a base for tile in water closet compartment walls when installed in accordance with GA-216 or ASTM C840 and the manufacturer's recommendations. Regular gypsum wallboard is permitted under tile or wall panels in other wall and ceiling areas when installed in accordance with GA-216 or ASTM C840.
Water-resistant gypsum backing board shall not be used in the following locations:
- Over a vapor retarder in shower or bathtub compartments.
- Where there will be direct exposure to water or in areas subject to continuous high humidity.
Gypsum lath or gypsum wallboard shall not be used as a backing for cement plaster.
Exception: Gypsum lath or gypsum wallboard is permitted, with a water-resistive barrier, as a backing for self-furred metal lath or self-furred wire fabric lath and cement plaster where either of the following conditions occur:
- On horizontal supports of ceilings or roof soffits.
- On interior walls.
Water-resistive barriers shall be installed as required in Section 1403.2 and, where applied over wood-based sheathing, shall include a water-resistive vapor-permeable barrier with a performance at least equivalent to two layers of water-resistive barrier complying with ASTM E2556, Type I. The individual layers shall be installed independently such that each layer provides a separate continuous plane and any flashing (installed in accordance with Section 1404.4) intended to drain to the water-resistive barrier is directed between the layers.
Exceptions:
- Where the water-resistive barrier that is applied over wood-based sheathing has a water resistance equal to or greater than that of a water-resistive barrier complying with ASTM E2556, Type II and is separated from the stucco by an intervening, substantially nonwater-absorbing layer or drainage space.
- Where the water-resistive barrier is applied over wood-based sheathing in Climate Zone 1A, 2A or 3A, a ventilated air space shall be provided between the stucco and water-resistive barrier.
Plastering gypsum plaster or cement plaster shall be not less than three coats where applied over metal lath or wire fabric lath and not less than two coats where applied over other bases permitted by this chapter.
Exception: Gypsum veneer plaster and cement plaster specifically designed and approved for one-coat applications.
Installation of lathing and plaster materials shall conform to Table 2511.1.1 and Section 2507.
INSTALLATION OF PLASTER CONSTRUCTION
MATERIAL | STANDARD |
Cement plaster | ASTM C926 |
Gypsum plaster | ASTM C842 |
Gypsum veneer plaster | ASTM C843 |
Interior lathing and furring | ASTM C841 |
Lathing and furring (cement plaster) | ASTM C1063 |
Steel framing | ASTM C754; C1007 |
First and second coats of cement plaster shall be applied and moist cured as set forth in ASTM C926 and Table 2512.6.
COAT | MINIMUM PERIOD MOIST CURING | MINIMUM INTERVAL BETWEEN COATS |
First | 48 hoursa | 48 hoursb |
Second | 48 hours | 7 daysc |
Finish | — | Note c |
- The first two coats shall be as required for the first coats of exterior plaster, except that the moist-curing time period between the first and second coats shall be not less than 24 hours. Moist curing shall not be required where job and weather conditions are favorable to the retention of moisture in the cement plaster for the required time period.
- Twenty-four-hour minimum interval between coats of interior cement plaster. For alternative method of application, see Section 2512.8.
- Finish coat plaster is permitted to be applied to interior cement plaster base coats after a 48-hour period.
The minimum thickness of reinforced gypsum concrete shall be 2 inches (51 mm) except the minimum required thickness shall be reduced to 11/2 inches (38 mm), provided that the following conditions are satisfied: