Roof–Ceiling Construction

Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:

• CRC § 8-31 High relevance — show source text

  R804.3 Roof construction. Cold-formed steel roof systems constructed in accordance with the provisions of this section shall consist of both ceiling joists and rafters in accordance with Figure R804.3 and fastened in accordance with Table R804.3.

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  ROOF-CEILING CONSTRUCTION

  FIGURE R804.3—COLD-FORMED STEEL ROOF CONSTRUCTION

  Col1	Col2
  CEILING JOIST ½ IN. GYPSUM BOARD LOAD-BEARING WALL WHEN INSTALLED RAFTER SUPPORT BRACE SHALL BE A MINIMUM OF 350s162-33 MIL C-SECTION, CONNECTED TO EACH CEILING JOIST AND RAFTER WITH 4 SCREWS AT EACH END (COPE FLANGES OF BAR AT CEILING JOIST CONNECTION OR USE GUSSET PLATE)	6 IN. MAX. TO CENTER OF SCREW PATTERN EAVE OVERHANG 2 FT. MAX. CEILING JOIST SPAN LOAD-BEARING WALL SHALL BE INSTALLED WHEN RAFTER BRACE IS USED LOAD-BEARING WALL

  For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mil = 0.0254 mm.

  TABLE R804.3—ROOF FRAMING FASTENING SCHEDULEa, b	Col2	Col3	Col4	Col5	Col6	Col7	Col8
  ** DESCRIPTION OF BUILDING ELEMENTS**	** DESCRIPTION OF BUILDING ELEMENTS**	** DESCRIPTION OF BUILDING ELEMENTS**	** NUMBER AND SIZE OF FASTENERSa**	** NUMBER AND SIZE OF FASTENERSa**	** NUMBER AND SIZE OF FASTENERSa**	** NUMBER AND SIZE OF FASTENERSa**	** SPACING OF FASTENERS**
  Roof sheathing (oriented strand board or plywood) to rafter	Roof sheathing (oriented strand board or plywood) to rafter	Roof sheathing (oriented strand board or plywood) to rafter	No. 8 screws	No. 8 screws	No. 8 screws	No. 8 screws	6″ o.c. on edges and 12″ o.c. at interior supports. 6″ o.c. at gable end truss.
  Gypsum board to ceiling joists	Gypsum board to ceiling joists	Gypsum board to ceiling joists	No. 6 screws	No. 6 screws	No. 6 screws	No. 6 screws	12″ o.c.
  Gable end truss to endwall top track	Gable end truss to endwall top track	Gable end truss to endwall top track	No. 10 screws	No. 10 screws	No. 10 screws	No. 10 screws	12″ o.c.
  Rafter to ceiling joist and to ridge member	Rafter to ceiling joist and to ridge member	Rafter to ceiling joist and to ridge member	Minimum No. 10 screws, in accordance with Table R804.3.1.1(3)	Minimum No. 10 screws, in accordance with Table R804.3.1.1(3)	Minimum No.

• CRC § 2025 High relevance — show source text

  Chapter 6 also regulates exterior windows and doors installed in walls. This chapter contains criteria for the performance of exterior windows and doors and includes provisions for testing and labeling, garage doors, windborne debris protection and anchorage details.

  Chapter 7 Wall Covering.

  Chapter 7 contains provisions for the design and construction of interior and exterior wall coverings. This chapter establishes the various types of materials, materials standards and methods of application permitted for use as interior coverings, including interior plaster, gypsum board, ceramic tile, wood veneer paneling, hardboard paneling, wood shakes and wood shingles. Chapter 7 also contains requirements for the use of vapor retarders for moisture control in walls.

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  Exterior wall coverings provide the weather-resistant exterior envelope that protects the building’s interior from the elements. Chapter 7 provides the requirements for wind resistance and water-resistive barrier for exterior wall coverings. This chapter prescribes the exterior wall coverings as well as the water-resistive barrier required beneath the exterior materials. Exterior wall coverings regulated by this section include aluminum, stone and masonry veneer, wood, hardboard, particleboard, wood structural panel siding, wood shakes and shingles, exterior plaster, steel, vinyl, fiber cement and exterior insulation finish systems.

  Chapter 8 Roof-Ceiling Construction.

  Chapter 8 regulates the design and construction of roof-ceiling systems. This chapter contains two roof-ceiling framing systems: wood framing and cold-formed steel framing. Allowable span tables are provided to simplify the selection of rafter and ceiling joist size for wood roof framing and cold-formed steel framing. Chapter 8 also provides requirements for the application of ceiling finishes, the proper ventilation of concealed spaces in roofs (e.g., enclosed attics and rafter spaces), unvented attic assemblies and attic access.

  Chapter 9 Roof Assemblies.

  Chapter 9 regulates the design and construction of roof assemblies. A roof assembly includes the roof deck, vapor retarder, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings.

  The types of roof covering materials and installation regulated by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and photovoltaic shingles. Chapter 9 also provides requirements for roof drainage, flashing, above deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.

  Chapter 10 Chimneys and Fireplaces.

  Chapter 10 contains requirements for the safe construction of masonry chimneys and fireplaces and establishes the standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; the factory-built type relies on the listing and labeling method of approval. Chapter 10 provides the requirements for seismic reinforcing and anchorage of masonry fireplaces and chimneys.

  Chapter 11 [RE] Energy Efficiency.

  Chapter 11 is not adopted in California. See California Energy Code, Title 24, Part 6.

  Chapter 12 Mechanical Administration.

• CRC § 6.1 High relevance — show source text

  R802.6.1 Finished ceiling material. If the finished ceiling material is installed on the ceiling prior to the attachment of the ceiling to the walls, such as in construction at a factory, a compression strip of the same thickness as the finished ceiling material shall be installed directly above the top plate of bearing walls if the compressive strength of the finished ceiling material is less than the loads it will be required to withstand. The compression strip shall cover the entire length of such top plate and shall be not less than one-half the width of the top plate. It shall be of material capable of transmitting the loads transferred through it.

  R802.7 Cutting, drilling and notching. Structural roof members shall not be cut, bored or notched in excess of the limitations specified in this section.

  R802.7.1 Sawn lumber. Cuts, notches and holes in solid lumber joists, rafters, blocking and beams shall comply with the provisions of Section R502.8.1 except that cantilevered portions of rafters shall be permitted in accordance with Section R802.7.1.1.

  R802.7.1.1 Cantilevered portions of rafters. Notches on cantilevered portions of rafters are permitted provided the dimension of the remaining portion of the rafter is not less than 3 [1] / 2 inches (89 mm) and the length of the cantilever does not exceed 24 inches (610 mm) in accordance with Figure R802.7.1.1.

  FIGURE R802.7.1.1—RAFTER NOTCH

  DEPTH, D

  NOT LESS THAN 3-1/2 INCHES (IRC 802.7.1.1)

  For SI: 1 inch = 25.4 mm.

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  ROOF-CEILING CONSTRUCTION

  R802.7.1.2 Ceiling joist taper cut. Taper cuts at the ends of the ceiling joist shall not exceed one-fourth the depth of the member in accordance with Figure R802.7.1.2.

  FIGURE R802.7.1.2—CEILING JOIST TAPER CUT

  DEPTH OF TAPER CUT, D/4 MAX. MEASURED AT

  INSIDE FACE

  OF SUPPORT

  R802.7.2 Engineered wood products. Cuts, notches and holes bored in trusses, structural composite lumber, structural gluedlaminated members, cross-laminated timber members or I-joists are prohibited except where permitted by the manufacturer’s recommendations or where the effects of such alterations are specifically considered in the design of the member by a registered design professional.

  R802.8 Lateral support. Roof framing members and ceiling joists having a depth-to-thickness ratio exceeding 5 to 1 based on nominal dimensions shall be provided with lateral support at points of bearing to prevent rotation. For roof rafters with ceiling joists attached in accordance with Table R602.3(1), the depth-to-thickness ratio for the total assembly shall be determined using the combined thickness of the rafter plus the attached ceiling joist.

  Exception: Roof trusses shall be braced in accordance with Section R802.10.3.

• CRC § 0.35 High relevance — show source text

  Ceiling diaphragm is composed of1/2-inch gypsum board (min. thickness) secured with screws spaced at 6 inches o.c. at panel edges and 12 inches o.c. infield. Use No. 8
  screws (min.) where framing members have a designation thickness of 54 mils or less and No. 10 screws (min.) where framing members have a designation thickness greater
  than 54 mils.
  b. Maximum aspect ratio (length/width) of diaphragms is 2:1.
  c. Building width is in the direction of horizontal framing members supported by the wall studs.
  d. Required diaphragm lengths are to be provided at each end of the structure.
  e. Multiplying required diaphragm lengths by 0.35 is permitted if all panel edges are blocked.
  f. Multiplying required diaphragm lengths by 0.9 is permitted if all panel edges are secured with screws spaced at 4 inches o.c.
  g. To determine the minimum diaphragm length for buildings with ceiling heights of 9 feet or 10 feet values in this table shall be multiplied by 1.15.|

  FIGURE R804.3.7.1(1)—CEILING DIAPHRAGM TO GABLE ENDWALL DETAIL

  CEILING JOISTS

  FLAT STUD OR TRACK BLOCKING AT 48 IN. O.C. AT FIRST TWO JOIST SPACES

  3 NO. 8 SCREWS AT EACH STUD

  STUD BLOCKING AT CEILING ELEVATION

  GABLE

  ENDWALL

  STUDS

  For SI: 1 inch = 25.4 mm.

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  FIGURE R804.3.7.1(2)—CEILING DIAPHRAGM TO SIDEWALL DETAIL

  ROOF-CEILING CONSTRUCTION

  ROOF RAFTER (OR TRUSS TOP CHORD)

  CEILING JOIST (OR TRUSS BOTTOM CHORD)

  WOOD STRUCTURAL

  PANEL OR GYPSUM

  BOARD DIAPHRAGM

  350T125-33 TRACK

  ROOF SHEATHING

  ROOF BLOCKING

  NO. 8 SCREWS AT 6 IN. O.C.

  STRUCTURAL WALL

  For SI: 1 inch = 25.4 mm.

  R804.3.7.2 Roof diaphragm. A roof diaphragm shall be provided by attaching not less than [3] / 8 -inch (9.5 mm) wood structural panel that complies with Section R803 to roof rafters or truss top chords in accordance with Table R804.3. Buildings with 3:1 or larger plan aspect ratio and with roof rafter slope (pitch) of 9:12 or larger shall have the roof rafters and ceiling joists blocked in accordance with Figure R804.3.7.2.

  FIGURE R804.3.7.2—ROOF BLOCKING DETAIL

  BE ATTACHED TO OUTSIDE FACE OF SHEATHING OR PREFERABLY DIRECTLY TO TRACK FLANGE PRIOR TO SHEATHING PLACEMENT AS SHOWN

  For SI: 1 mil = 0.0254 mm, 1 inch = 25.4 mm, 1 foot = 304.8 mm.

  2025 CALIFORNIA RESIDENTIAL CODE 8-43

• CRC § 5.2.1 High relevance — show source text

  ROOF-CEILING CONSTRUCTION

  R802.5.2.1 Ceiling joists lapped. Ends of ceiling joists shall be lapped not less than 3 inches (76 mm) or butted over bearing partitions or beams and toenailed to the bearing member. Where ceiling joists are used to provide the continuous tie across the building, lapped joists shall be nailed together in accordance with Table R802.5.2(1) and butted joists shall be tied together with a connection of equivalent capacity. Laps in joists that do not provide the continuous tie across the building shall be permitted to be nailed in accordance with Table R602.3(1).

  R802.5.2.2 Rafter ties. Wood rafter ties shall be not less than 2 inches by 4 inches (51 mm × 102 mm) installed in accordance with Table R802.5.2(1) at a maximum of 24 inches (610 mm) on center. Other approved rafter tie methods shall be permitted.

  R802.5.2.3 Blocking. Blocking shall be not less than utility grade lumber. R802.6 Bearing. The ends of each rafter or ceiling joist shall have not less than 1 [1] / 2 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete. The bearing on masonry or concrete shall be direct, or a sill plate of 2-inch (51 mm) minimum nominal thickness shall be provided under the rafter or ceiling joist. The sill plate shall provide a minimum nominal bearing area of 48 square inches (30 968 mm [2] ). Where the roof pitch is greater than or equal to 3 units vertical in 12 units horizontal (25-percent slope), and ceiling joists or rafter ties are connected to rafters to provide a continuous tension tie in accordance with Section R802.5.2, vertical bearing of the top of the rafter against the ridge board shall satisfy this bearing requirement.

  R802.6.1 Finished ceiling material. If the finished ceiling material is installed on the ceiling prior to the attachment of the ceiling to the walls, such as in construction at a factory, a compression strip of the same thickness as the finished ceiling material shall be installed directly above the top plate of bearing walls if the compressive strength of the finished ceiling material is less than the loads it will be required to withstand. The compression strip shall cover the entire length of such top plate and shall be not less than one-half the width of the top plate. It shall be of material capable of transmitting the loads transferred through it.

  R802.7 Cutting, drilling and notching. Structural roof members shall not be cut, bored or notched in excess of the limitations specified in this section.

  R802.7.1 Sawn lumber. Cuts, notches and holes in solid lumber joists, rafters, blocking and beams shall comply with the provisions of Section R502.8.1 except that cantilevered portions of rafters shall be permitted in accordance with Section R802.7.1.1.

  R802.7.1.1 Cantilevered portions of rafters. Notches on cantilevered portions of rafters are permitted provided the dimension of the remaining portion of the rafter is not less than 3 [1] / 2 inches (89 mm) and the length of the cantilever does not exceed 24 inches (610 mm) in accordance with Figure R802.7.1.1.

• CRC § 1.1 High relevance — show source text

  1.1 Note||||X|||||||||||||||||||| |R802.10.2||||X|||||||||||||||||||| |R803.2.1.2|||X||||||||||||||||||||| |R806 Note||||||||||||||||||||X|||| |R806.1.1|||X|X|||||||||||||||||||| |R807.1||||X||||||||||||||||||||

  The state agency does not adopt sections identified with the following symbol: †

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  8-2 2025 CALIFORNIA RESIDENTIAL CODE

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  8 ROOF-CEILING CONSTRUCTION

  User notes:

  About this chapter: Chapter 8 addresses the design and construction of roof-ceiling systems. This chapter contains two roof-ceiling framing systems: wood framing and cold-formed steel framing. Allowable span tables are provided to simplify the selection of rafter and ceiling joist size for wood roof framing and cold-formed steel framing. Chapter 8 also provides requirements for the application of ceiling finishes, the proper ventilation of concealed spaces in roofs (for example, enclosed attics and rafter spaces), unvented attic assemblies and attic access.

  SECTION R801—GENERAL

  R801.1 Application. The provisions of this chapter shall control the design and construction of the roof-ceiling system for buildings.

  R801.2 Requirements. Roof and ceiling construction shall be capable of accommodating all loads imposed in accordance with Section R301 and of transmitting the resulting loads to the supporting structural elements.

  R801.3 Roof drainage. In areas where expansive soils or collapsible soils are known to exist, all dwellings and townhouses shall have a controlled method of water disposal from roofs that will collect and discharge roof drainage to the ground surface not less than 5 feet (1524 mm) from foundation walls or to an approved drainage system.

  SECTION R802—WOOD ROOF FRAMING

  R802.1 General. Wood and wood-based products used for load-supporting purposes shall conform to the applicable provisions of this section.

  R802.1.1 Sawn lumber. Sawn lumber shall be identified by a grade mark of an accredited lumber grading or inspection agency and have design values certified by an accreditation body that complies with DOC PS 20. In lieu of a grade mark, a certificate of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted.

  Note: See Section R301.1.1.1 for limited-density owner- built rural dwellings.

  R802.1.1.1 End-jointed lumber. Approved end-jointed lumber identified by a grade mark conforming to Section R802.1.1 shall be permitted to be used interchangeably with solid-sawn members of the same species and grade. End-jointed lumber used in an assembly required elsewhere in this code to have a fire-resistance rating shall have the designation “Heat-Resistant Adhesive” or “HRA” included in its grade mark.

  R802.1.2 Structural glued-laminated timbers. Glued-laminated timbers shall be manufactured and identified as required in ANSI A190.1, ANSI 117 and ASTM D3737.

  R802.1.3 Structural log members. Structural log members shall comply with the provisions of ICC 400.

• CRC § 5.2 High relevance — show source text

  Tabulated requirements are based on 10 psf roof dead load in combination with the specified roof snow load and roof live load.|

  TABLE R802.5.2(2)—HEEL JOINT CONNECTION ADJUSTMENT FACTORS	Col2
  HC/HR a, b	HEEL JOINT CONNECTION ADJUSTMENT FACTOR
  1/3	1.5
  1/4	1.33
  1/5	1.25
  1/6	1.2
  1/10 or less	1.11
  a.HC = Height of ceiling joists or rafter ties measured vertically from the top of the rafter support walls to the bottom of the ceiling joists or rafter ties;HR = Height of roof ridge measured vertically from the top of the rafter support walls to the bottom of the roof ridge. b. Where_HC/HR_ exceeds 1/3, connections shall be designed in accordance with accepted engineering practice.	a.HC = Height of ceiling joists or rafter ties measured vertically from the top of the rafter support walls to the bottom of the ceiling joists or rafter ties;HR = Height of roof ridge measured vertically from the top of the rafter support walls to the bottom of the roof ridge. b. Where_HC/HR_ exceeds 1/3, connections shall be designed in accordance with accepted engineering practice.

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  ROOF-CEILING CONSTRUCTION

  R802.5.2.1 Ceiling joists lapped. Ends of ceiling joists shall be lapped not less than 3 inches (76 mm) or butted over bearing partitions or beams and toenailed to the bearing member. Where ceiling joists are used to provide the continuous tie across the building, lapped joists shall be nailed together in accordance with Table R802.5.2(1) and butted joists shall be tied together with a connection of equivalent capacity. Laps in joists that do not provide the continuous tie across the building shall be permitted to be nailed in accordance with Table R602.3(1).

  R802.5.2.2 Rafter ties. Wood rafter ties shall be not less than 2 inches by 4 inches (51 mm × 102 mm) installed in accordance with Table R802.5.2(1) at a maximum of 24 inches (610 mm) on center. Other approved rafter tie methods shall be permitted.

  R802.5.2.3 Blocking. Blocking shall be not less than utility grade lumber. R802.6 Bearing. The ends of each rafter or ceiling joist shall have not less than 1 [1] / 2 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete. The bearing on masonry or concrete shall be direct, or a sill plate of 2-inch (51 mm) minimum nominal thickness shall be provided under the rafter or ceiling joist. The sill plate shall provide a minimum nominal bearing area of 48 square inches (30 968 mm [2] ).

• CRC § 6-106 High relevance — show source text

  R607 Glass Unit Masonry . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-106

  R608 Exterior Concrete Wall Construction. . . . . . . . . . . . 6-107

  R609 Exterior Windows and Doors. . . . . . . . . . . . . . . . . . . 6-172

  R610 Structural Insulated Panel Wall Construction . . . 6-175

  CHAPTER 7 WALL COVERING. . . . . . . . . . . . . . . . . . . . . . . . 7-3

  R701 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

  R702 Interior Covering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

  R703 Exterior Wall Covering . . . . . . . . . . . . . . . . . . . . . . . . . 7-10

  R704 Exterior Soffits and Fascias. . . . . . . . . . . . . . . . . . . . . 7-32

  R705 BIPV Systems for Exterior Wall Coverings and Fenestration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-35

  CHAPTER 8 ROOF-CEILING CONSTRUCTION. . . . . . . . . . . 8-3

  R801 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

  R802 Wood Roof Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

  R803 Roof Sheathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-30

  R804 Cold-Formed Steel Roof Framing . . . . . . . . . . . . . . . 8-31

  R805 Ceiling Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44

  R806 Roof Ventilation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44

  R807 Attic Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-46

  CHAPTER 9 ROOF ASSEMBLIES . . . . . . . . . . . . . . . . . . . . . .9-3

  R901 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3

  R902 Fire Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3

• CRC § 3.5 High relevance — show source text

  FIGURE R804.3.5(1)—ROOF OR CEILING OPENING

  For SI: 1 foot = 304.8 mm.

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  ROOF-CEILING CONSTRUCTION

  FIGURE R804.3.5(2)—HEADER TO TRIMMER CONNECTION

  MINIMUM 2 IN. × 2 IN. CLIP ANGLE WITH 4 NO. 8 SCREWS THROUGH EACH LEG, BOTH SIDES OF CONNECTION

  For SI: 1 inch = 25.4 mm.

  R804.3.6 Roof trusses. Cold-formed steel trusses shall be designed and installed in accordance with AISI S230, Section F6. In the absence of specific bracing requirements, trusses shall be braced in accordance with accepted industry practices, such as the SBCA Cold-Formed Steel Building Component Safety Information (CFSBCSI) Guide to Good Practice for Handling, Installing & Bracing of Cold-Formed Steel Trusses. Trusses shall be connected to the top track of the load-bearing wall in accordance with Table R804.3, either with the required number of No. 10 screws applied through the flange of the truss or by using a 54-mil (1.37 mm) clip angle with the required number of No. 10 screws in each leg.

  R804.3.7 Ceiling and roof diaphragms. Ceiling and roof diaphragms shall be in accordance with this section. R804.3.7.1 Ceiling diaphragms. At gable endwalls a ceiling diaphragm shall be provided by attaching a minimum [1] / 2 -inch (12.7 mm) gypsum board or a minimum [3] / 8 -inch (9.5 mm) wood structural panel sheathing, that complies with Section R803, to the bottom of ceiling joists or roof trusses and connected to wall framing in accordance with Figures R804.3.7.1(1) and R804.3.7.1(2), unless studs are designed as full height without bracing at the ceiling. Flat blocking shall consist of C-shaped or track section with a minimum thickness of 33 mils (0.84 mm). For a gypsum board sheathed ceiling, the diaphragm length shall be in accordance with Table R804.3.7.1. For a wood structural panel sheathed ceiling, the diaphragm length shall be not less than 12 feet (3658 mm) for building widths less than 36 feet (10 973 mm), or not less than 14 feet (4267 mm) for building widths greater than or equal to 36 feet (10 973 mm).

  The ceiling diaphragm shall be secured with screws spaced at a maximum 6 inches (152 mm) o.c. at panel edges and a maximum 12 inches (305 mm) o.c. in the field. The required lengths in Table R804.3.7.1 for gypsum board sheathed ceiling diaphragms shall be permitted to be multiplied by 0.35 if all panel edges are blocked. Multiplying the required lengths in Table R804.3.7.1 for gypsum board sheathed ceiling diaphragms by 0.9 shall be permitted if all panel edges are secured with screws spaced at 4 inches (102 mm) o.c.

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• CRC § 3.7.1 High relevance — show source text

  FIGURE R804.3.7.1(2)—CEILING DIAPHRAGM TO SIDEWALL DETAIL

  ROOF-CEILING CONSTRUCTION

  ROOF RAFTER (OR TRUSS TOP CHORD)

  CEILING JOIST (OR TRUSS BOTTOM CHORD)

  WOOD STRUCTURAL

  PANEL OR GYPSUM

  BOARD DIAPHRAGM

  350T125-33 TRACK

  ROOF SHEATHING

  ROOF BLOCKING

  NO. 8 SCREWS AT 6 IN. O.C.

  STRUCTURAL WALL

  For SI: 1 inch = 25.4 mm.

  R804.3.7.2 Roof diaphragm. A roof diaphragm shall be provided by attaching not less than [3] / 8 -inch (9.5 mm) wood structural panel that complies with Section R803 to roof rafters or truss top chords in accordance with Table R804.3. Buildings with 3:1 or larger plan aspect ratio and with roof rafter slope (pitch) of 9:12 or larger shall have the roof rafters and ceiling joists blocked in accordance with Figure R804.3.7.2.

  FIGURE R804.3.7.2—ROOF BLOCKING DETAIL

  BE ATTACHED TO OUTSIDE FACE OF SHEATHING OR PREFERABLY DIRECTLY TO TRACK FLANGE PRIOR TO SHEATHING PLACEMENT AS SHOWN

  For SI: 1 mil = 0.0254 mm, 1 inch = 25.4 mm, 1 foot = 304.8 mm.

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  ROOF-CEILING CONSTRUCTION

  R804.3.8 Roof tie-down. Roof assemblies shall be connected to walls below in accordance with Table R804.3. A continuous load path shall be provided to transfer uplift loads to the foundation.

  SECTION R805—CEILING FINISHES

  R805.1 Ceiling installation. Ceilings shall be installed in accordance with the requirements for interior wall finishes as provided in Sections R702.1 through R702.6.

  SECTION R806—ROOF VENTILATION

  Note: The IECC climate zones used by this section differ from those used by the California Energy Code to determine applicability of energy efficiency measures. Comparison of IECC and California Energy Code climate zones is shown in Table R702.7.3.

  R806.1 Ventilation required. Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow. Ventilation openings shall have a least dimension of [1] / 16 inch (1.6 mm) minimum and [1] / 4 inch (6.4 mm) maximum. Ventilation openings having a least dimension larger than [1] / 4 inch (6.4 mm) shall be provided with corrosion-resistant wire cloth screening, hardware cloth, perforated vinyl or similar material with openings having a least dimension of [1] / 16 inch (1.6 mm) minimum and [1] / 4 inch (6.4 mm) maximum. Openings in roof framing members shall conform to the requirements of Section R802.7.

• CRC § 8-35 High relevance — show source text

  Lateral bracing shall be installed perpendicular to the ceiling joists and shall be fastened to the top flange of each joist with one No. 8 screw. Blocking shall be installed between joists in line with bracing at a maximum spacing of 12 feet (3658 mm) measured perpendicular to the joists. Ends of lateral bracing shall be attached to blocking or anchored to a stable building component with two No. 8 screws.

  2025 CALIFORNIA RESIDENTIAL CODE 8-35

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  ROOF-CEILING CONSTRUCTION

  FIGURE R804.3.1.3(1)—CEILING JOIST TOP FLANGE BRACING WITH C-SHAPED, TRACK OR COLD-ROLLED CHANNEL

  ANCHORAGE AT END IS REQUIRED.

  CEILING FRAMING MEMBERS. GYPSUM BOARD ON BOTTOM CHORD NOT SHOWN FOR CLARITY.

  BRACING. USE 1 NO. 8 SCREW TO EACH JOIST.

  FIGURE R804.3.1.3(2)—CEILING JOIST TOP FLANGE BRACING WITH CONTINUOUS STEEL STRAP AND BLOCKING

  ANCHORAGE AT END IS REQUIRED.

  SHORT SEGMENT OF

  USED AS BLOCKING: AT STRAP SPLICE LOCATIONS, AT ENDS, AND AT MAX. 12 FT O.C.

  For SI: 1 foot = 304.8 mm.

  R804.3.1.4 Ceiling joist splicing. Splices in ceiling joists shall be permitted, if ceiling joist splices are supported at interior bearing points and are constructed in accordance with Figure R804.3.1.4. The number of screws on each side of the splice shall be the same as required for the heel joint connection in Table R804.3.1.1(3).

  8-36 2025 CALIFORNIA RESIDENTIAL CODE

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  ROOF-CEILING CONSTRUCTION

  FIGURE R804.3.1.4—SPLICED CEILING JOISTS

  TRACK

  For SI: 1 inch = 25.4 mm.

  R804.3.2 Roof rafters. Cold-formed steel roof rafters shall be in accordance with this section.

  R804.3.2.1 Minimum roof rafter sizes. Roof rafter size and thickness shall be determined in accordance with the limits set forth in Table R804.3.2.1(1) based on the horizontal projection of the roof rafter span. For determination of roof rafter sizes, reduction of roof spans shall be permitted where a roof rafter support brace is installed in accordance with Section R804.3.2.2. The reduced roof rafter span shall be taken as the larger of the distances from the roof rafter support brace to the ridge or to the heel measured horizontally.

  For the purpose of determining roof rafter sizes in Table R804.3.2.1(1), ultimate design wind speeds shall be converted to equivalent ground snow loads in accordance with Table R804.3.2.1(2). Roof rafter sizes shall be based on the higher of the ground snow load or the equivalent snow load converted from the ultimate design wind speed.

  |TABLE R804.3.2.1(1)—ROOF RAFTER SPANSa, b, c,

• CRC § 0.292 High relevance — show source text

  Screws for attaching structural sheathing to cold-formed steel roof framing shall have a minimum head diameter of 0.292 inch (7.4 mm) with countersunk heads and shall be installed with a minimum edge distance of [3] / 8 inch (9.5 mm). Gypsum board ceilings shall be attached to cold-formed steel joists with minimum No. 6 screws conforming to ASTM C954 or ASTM C1513 with a buglehead style and shall be installed in accordance with Section R805. For all connections, screws shall extend through the steel not fewer than three exposed threads. Fasteners shall have rust-inhibitive coating suitable for the installation in which they are being used, or be manufactured from material not susceptible to corrosion.

  R804.2.6 Web holes, web hole reinforcing and web hole patching. Web holes in roof or ceiling joists shall comply with the conditions as prescribed in AISI S230, Section A4.5. Web holes not in conformance to the conditions of AISI S230, Section A4.5 shall be reinforced in accordance with the provisions of AISI S230, Section A4.6 or patched in accordance with the provisions of AISI S230, Section A4.7.

  R804.3 Roof construction. Cold-formed steel roof systems constructed in accordance with the provisions of this section shall consist of both ceiling joists and rafters in accordance with Figure R804.3 and fastened in accordance with Table R804.3.

  2025 CALIFORNIA RESIDENTIAL CODE 8-31

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  ROOF-CEILING CONSTRUCTION

  FIGURE R804.3—COLD-FORMED STEEL ROOF CONSTRUCTION

  Col1	Col2
  CEILING JOIST ½ IN. GYPSUM BOARD LOAD-BEARING WALL WHEN INSTALLED RAFTER SUPPORT BRACE SHALL BE A MINIMUM OF 350s162-33 MIL C-SECTION, CONNECTED TO EACH CEILING JOIST AND RAFTER WITH 4 SCREWS AT EACH END (COPE FLANGES OF BAR AT CEILING JOIST CONNECTION OR USE GUSSET PLATE)	6 IN. MAX. TO CENTER OF SCREW PATTERN EAVE OVERHANG 2 FT. MAX. CEILING JOIST SPAN LOAD-BEARING WALL SHALL BE INSTALLED WHEN RAFTER BRACE IS USED LOAD-BEARING WALL

  For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mil = 0.0254 mm.