Wood

NYC Admin. Code tit. 27, ch. 1, subch. 10, art. 7

in effect

NYC Admin. Code § 27-617 General requirements.

§ 27-617 General requirements. Materials (other than non-stress grade lumber), design, and construction methods shall meet the requirements of the following reference standards: (a) Lumber and timber. Reference standard RS 10-8. (b) Plywood. Reference standard RS 10-9. (c) Structural glued-laminated lumber. Reference standard RS 10-18.

NYC Admin. Code § 27-618 Identification.

§ 27-618 Identification. Except as provided for in subdivisions (a) and (c) of this section, all wood used for structural elements shall be identified as to grade and shall bear an identifying mark of an approved bureau or agency performing the grading, or the official grade mark and trade mark of the bureau or association under whose rules the wood was graded, in accordance with the following: (a) Lumber and timber. All lumber and timber, including non-stress grade lumber, shall be identified by the grade mark of a lumber grading or inspection bureau or agency approved by the commissioner, except that pre-cut material and rough-sawn lumber may be covered by a certificate of inspection issued by a lumber grading or inspection agency approved by the commissioner in lieu of grade marking. (b) Plywood. Plywood used structurally shall bear identification as to grade, type, and species group, or identification index. Such identification shall be affixed by and identified by the trademarks of a testing and grading agency approved by the commissioner. (c) Glued-laminated. Glued-laminated structural members shall bear identification and/or shall be accompanied by certification in accordance with the provisions of reference standard RS 10-18. (d) Resawn lumber. Resawn (or reused) lumber shall be marked in accordance with its regraded status.

NYC Admin. Code § 27-619 Use of non-stress grade wood.

§ 27-619 Use of non-stress grade wood. The use of non-stress grade wood in structural elements shall be limited to the following conditions: (a) Studs, joists, and rafters proportioned on the basis of the empirical provisions of section 27-622 of this article. (b) The architect or engineer responsible for the design may assign an allowable stress value for the proposed material based on the provisions of reference standard RS 10-8 relating to "other species and grade". Under such condition, the required species and grade of wood, together with the assigned stress value, shall be conspicuously indicated on the plans.

NYC Admin. Code § 27-620 Quality control.

§ 27-620 Quality control. Inspection of the fabrication of glued-laminated assemblies, as stipulated in table 10-2, shall include a check of sizes of members, of fit, and of gluing operations.

NYC Admin. Code § 27-621 General construction requirements.

§ 27-621 General construction requirements. The provisions of this section shall be considered as supplemental to the provisions of the applicable reference standards. (a) Firecutting. The ends of wood beams, joists, and rafters resting on masonry or concrete walls shall be firecut to a bevel of three inches in their depth. (b) Protection of members. (1) Positive drainage shall be provided for all areas under the building not occupied by basements or cellars. (2) All loose wood and debris and all wood forms shall be removed from spaces under the building. All stumps and roots shall be grubbed to a minimum depth of twelve inches. (3) Wood members embedded in the ground and used for the support of buildings shall be treated. (4) Wood joists or wood structural floors closer than eighteen inches, wood girders closer than twelve inches, or sills closer than eight inches to an exposed ground surface within or without the building shall be treated or shall be of an equivalent resistant species. (5) Sleepers, sills, columns, and posts supported on concrete or masonry piers shall be treated or shall be of an equivalent resistant species unless isolated from the ground as specified in paragraph four of this subdivision or by a concrete slab. Where the isolation consists of a concrete slab-on-grade, the sleepers, sills, columns, or posts shall be raised at least three inches above the top of such slab. (6) Ends of wood girders entering masonry or concrete walls shall be provided with a minimum one-half inch air space on top, sides, and at the end, unless the girder is treated or is of an equivalent resistant species. (7) Wood or plywood used as siding or a combination of siding and sheathing shall be isolated from exposed ground by at least six inches. (8) Crawl spaces shall be ventilated as required in subchapter twelve of this chapter. (9) Where treated timber is required, the preservative treatment shall comply with reference standards RS 10-20 and RS 10-22. Treatment of wood poles shall comply with reference standard RS 10-28. All treated wood shall be handled in accordance with the provisions of reference standard RS 10-29.

NYC Admin. Code § 27-622 Empirical provisions in lieu of design.

§ 27-622 Empirical provisions in lieu of design. The provisions of this section may be used in lieu of structural analysis only for those buildings in occupancy group J-3 where the specific occupancies correspond to a live load requirement of forty psf, or less, and to constructions wherein the supporting framing consists of multiple, closely spaced members, such as joists, studs, platform or balloon frames. All wood structural members in other classes of construction shall be proportioned on the basis of the analysis of stresses. All requirements established in this section may be reduced when an analysis of stresses, executed in accordance with reference standard RS 10-8, indicates such reduction is feasible. Sizes of wood members stated in this section are nominal sizes. (a) Stud walls and partitions. (1) Studs shall be of equivalent or better grade than the minimum grades for the various species as established in reference standard RS 10-13. (2) Corner posts shall be 3-stud members or members of equivalent strength. (3) Load bearing studs shall be set with the larger cross section dimension perpendicular to the wall or partition. Studs in exterior walls of one story buildings of construction class II-D and II-E shall be at least two inches by three inches spaced not more than sixteen inches on center, or where studs are two inches by four inches, spaced not more than twenty-four inches on center. Studs for other classes of construction shall be at least two inches by four inches spaced not more than sixteen inches on center. (4) Stud walls resting on concrete or masonry shall have sills at least two inches in nominal thickness. Where such sills bear on concrete, they shall be fastened with minimum one-half inch bolts embedded at least six inches. Each sill piece shall have at least two anchor bolts, with one bolt located at least one inch from each end of the plate, and with intermediate spacing not more than eight feet. Where such sills bear on masonry, they shall be anchored in accordance with the applicable provisions of reference standard RS 10-1. (5) Stud partitions that rest directly over each other and are not parallel to floor joists or beams may extend down between the joists and rest on the top plate of the partition, partition girder, or foundation below, or may be constructed on sill plates running on top of the beams or joists. (6) All load bearing stud partitions shall be supported on walls, other partitions, double joists or beams, solid bridging, or on beams at least as wide as the studs. Joists supporting a partition parallel to the joists wherein the joists are spaced apart to permit the passage of piping or duct work shall be provided with solid blocking at intervals of not more than sixteen inches. (7) Load bearing partitions perpendicular to joists shall not be offset from supporting girders, walls or partitions by more than the depth of the joists unless the joists are proportioned on the basis of analysis of stress. (8) In interior walls and in bearing partitions, double studs shall be provided at the sides of openings that are greater than three feet six inches up to six feet in width, and triple-studs shall be provided at the sides of openings of greater width. (9) Headers shall be provided over each opening in exterior walls and bearing partitions. Where the opening does not exceed three feet, each end of the header shall be supported on a stud or framing anchor. Where the opening exceeds three feet in width each end of the header shall be supported on one stud and where the opening exceeds six feet each end shall be supported on two studs. (10) All studs in exterior walls and in bearing partitions shall be capped with double top plates installed to provide overlapping at corners and at intersections with other walls and bearing partitions. End joists in double top plates shall be offset at least twenty-four inches. In lieu of double top plates, a continuous header of similar dimensions may be used. For platform frame construction, studs shall rest on a single bottom plate. (b) Bracing of exterior walls. Exterior stud walls shall be braced by one inch by four inch continuous diagonal strips let into the face of the studs and into the top and bottom plates at each corner of the building. Bracing may also be provided by one of the following means: (1) Wood board sheathing of one inch nominal thickness, applied diagonally. (2) For one and two-story dwellings, plywood sheathing at least four feet by eight feet (except where cut to fit around openings and for similar purposes) and at least five-sixteenths of an inch thick on studs spaced sixteen inches or less on centers and at least three-eighths of an inch thick on studs spaced more than sixteen inches but not exceeding twenty-four inches on centers. (3) For one story dwellings and for the upper story of two story dwellings, fiberboard sheathing applied vertically in panels at least four feet by eight feet (except where cut to fit around openings and for similar purposes). Fiberboard sheathing shall be at least one-half inch thick and shall conform to the provisions of reference standard RS 10-27. (4) For one story dwellings and for the upper story of two story dwellings, gypsum board sheathing applied horizontally in panels at least two feet by eight feet (except where cut to fit around openings and for similar purposes). Gypsum boards shall be at least one-half inch thick and shall conform to the provisions of reference standard RS 10-19. (c) Floor and roof framing. (1) SPAN TABLES. Joists and rafters may be used in accordance with reference standard RS 10-13. (2) BRIDGING. In all floor and roof and roof framing, there shall be at least one line of bridging for each eight feet of span. The bridging shall consist of at least one inch by three inch lumber or equivalent metal bracing. A line of bridging or solid blocking shall also be required at supports unless lateral support is provided by nailing to a beam, header, or to the studs. Midspan bridging is not required for floor or roof framing in one- and two-family dwellings where joist depth does not exceed twelve inches. Bridging shall bear securely against and be anchored to the members to be braced. (3) NOTCHES. Notches in the ends of joists and rafters shall not exceed one-fourth the depth unless adequate reinforcement is provided or analysis of stresses indicates that larger openings are feasible without the necessity for reinforcement. Notches in joists or rafters, located in the span shall not exceed one-sixth the depth and shall not be located in the middle third of the span. Bored holes shall not be within two inches of the top or bottom of the joists or rafter and the diameter of any such hole shall not exceed one-third the depth. For stair stringers, the minimum effective depth of the wood at any notch shall be three and one-half inches unless the stringer is continuously supported on a wall or partition. (4) SUPPORT. a. Floor or roof framing may be supported on stud partitions. b. Tail beams over twelve feet long and all header and trimmer beams over six feet long shall be hung in metal stirrups having anchors, or by other methods providing adequate support. Trimmers and headers shall be doubled where the header is four feet or more in length. c. Except where supported on a one inch by four inch ribbon strip and nailed to the adjoining stud, the ends of floor joists shall have at least one and one-half inches of bearing on wood or metal, nor less than four inches on masonry. d. Joists framing from opposite sides of and supported on a beam, girder, or partition shall be lapped at least four inches and fastened, butted end-to-end and tied by metal straps or dogs, or otherwise tied together in a manner providing adequate support. e. Joists framing into the side of a wood girder shall be supported by framing anchors, on ledger strips at least two inches by two inches, or by equivalent methods. f. Wood joists and rafters bearing on masonry walls shall be anchored to such walls in accordance with the applicable provisions of reference standard RS 10-1. (5) RAFTERS AND CEILING JOISTS. a. Where rafters meet to form a ridge, they shall be placed directly opposite each other and nailed to a ridge board at least one inch thick, and not less than the cut end of the rafters in depth. b. Provisions shall be made to resist the thrust from inclined rafters by connection of collar beams at least one inch by six inches, by connection to joists, or by equivalent means. c. Where ceiling joists are not parallel to rafters, subflooring or metal straps attached to the ends of the rafters shall be installed in a manner to provide a continuous tie across the building. d. Ceiling joists shall be continuous, or where they meet over interior partitions, shall be securely joined to provide a continuous tie across the building. e. Valley rafters shall be double members. Hip rafters may be single members. Valley and hip rafters shall be two inches deeper than jack rafters. f. Trussed rafters shall be designed in accordance with the provisions of reference standard RS 10-8. (6) Built-up members shall be securely spiked or bolted together and provision shall be made to resist the horizontal shear between laminations. (d) Nailing schedule. The size and number of nails for connections shall be in accordance with table 10-4.

NYC Admin. Code § 27-623 Heavy timber construction (construction class II-A).

§ 27-623 Heavy timber construction (construction class II-A). (a) Minimum sizes of members. To conform to the fire resistance rating requirements for heavy timber construction (construction class II-A), members shall be solid sawn or solid glue-laminated and of the following minimum dimensions: (Sizes of wood members indicated in this section are nominal sizes). (1) COLUMNS, FRAMES AND ARCHES. a. Columns shall be at least eight inches in all dimensions when supporting floor loads, and at least six inches wide and eight inches deep when supporting roof and ceiling loads only. b. Beams and girders shall be at least six inches wide and ten inches deep. c. Frames or arches that spring from grade or the floor line and support floor loads shall be at least eight inches in all dimensions. d. Timber trusses supporting floor loads shall have members at least eight inches in all dimensions. e. Frames or arches for roof construction that spring from grade or the floor line and do not support floor loads shall have members at least six inches wide and eight inches deep for the lower half of the height, and at least six inches deep for the upper half. f. Frames or arches for roof construction that spring from the top of walls or wall abutments, framed timber trusses, and other roof framing, which do not support floor loads, shall have members at least four inches wide and six inches deep. Spaced members may be composed of two or more pieces at least three inches thick when blocked solidly through their intervening spaces or when such spaces are tightly closed by a continuous wood cover plate at least two inches thick secured to the underside of the members. Splice plates shall be at least three inches thick. When protected by approved automatic sprinklers under the roof deck, framing members shall be at least three inches wide. (2) FLOORS. a. Planks shall be splined or tongue-and-groove, not less than three inches thick, covered with one inch tongue-and-groove flooring, laid crosswise or diagonally to the plank, or other surface having equivalent fire resistance; or shall be, b. At least four inches wide, set on edge close together and well spiked, and covered the same as for three inch thick plank. The planks shall be laid so that there is no continuous line of end joints except at points of support. Floors shall not extend closer than one-half inch to walls to provide an expansion joint, but the joint shall be covered at top or bottom to avoid flue action. (3) ROOF DECKS. Roof decks shall be splined or tongue-and-groove planks at least two inches thick; or tongue-and-groove plywood panels (bonded with exterior glue) at least one and one-eighth inch thick, with face grain perpendicular to supports that shall be spaced not more than forty-eight inches on center; or of planks at least three inches wide set on edge close together and laid as required for floors. (b) Construction details. Self releasing type wall plate boxes or approved hangers shall be provided where beams and girders enter masonry. Table 10-4 Nailing Schedule Building Element Nail Type Number and Distribution Stud to sole plate Common-toe-nail 4 – 8d Stud to cap plate Common-end-nail 2 – 16d Double studs Common-direct 10d 12 in. o. c. or 16d 30 in. o.c. Corner studs Common-direct 16d 30 in. o.c. Sole plate to joist or blocking Common 16d 16 in. o.c. Double cap plate Common-direct 16d 24 in. o. c. Cap plate laps Common-direct 3 – 16d Ribbon strip, 6 in. or less Common-direct 2 – 10d each bearing Ribbon strip, over 6 in. Common-direct 3 – 10d each bearing Roof rafter to plate Common-toe-nail 3 – 16d Roof rafter to ridge Common-toe-nail 2 – 16d Jack rafter to hip Common-toe-nail 3 – 10d Floor joists to studs (no ceiling joists) Common-direct 5 – 10d or 3 – 16d Floor joists to studs (with ceiling joists) Common-direct 2 – 10d Floor joists to sill or girder Common-toe-nail 2 – 16d Double-joist to joist Common-direct 10d – staggered at 16 in. Ledger strip Common-direct 3 – 16d at each joist Ceiling joists to plate Common-toe-nail 2 – 16d Ceiling joists to every rafter Common-direct (See table below) Ceiling joists (laps over partitions) Common-direct 3 – 16d Collar beam Common-direct 4 – 10d Bridging to joists and rafters Common-direct 2 – 8d each end Bridging to studs Common-direct or toe 2 – 10d each end Diagonal brace (to stud and plate) Common-direct 2 – 8d each bearing Tail beams to headers (when nailing permitted) Common-end 1 – 20d each 4 sq. ft. floor area Header beams to trimmers (when nailing permitted) Common-end 1 – 20d each 8 sq. ft. floor area 1 in. Subflooring (6 in. or less in width) Common-direct 2 – 8d each joist 1 in. Subflooring (over 6 in. in width) Common-direct 3 – 8d each joist 2 in. Subflooring Common-direct 2 – 20d each joist 1 in. Wall sheathing (8 in. or less in width) Common-direct 2 – 8d each stud 1 in. Wall sheathing (over 8 in. in width) Common-direct 3 – 8d each stud Plywood sheathing and subflooring a 1 in. Roof sheathing (6 in. or less in width) Common-direct 2 – 8d each rafter 1 in. Roof sheathing (over 6 in. in width) Common-direct 3 – 8d each rafter Shingles, wood Corrosion-resistive 2 – No. 15 B&S each bearing Weather boarding Corrosion-resistive 2 – 8d each bearing 1/2 in. Fiberboard sheathing 1 1/2 in. galvanized roofing nail 6d common nail 16 ga. galvanized staples, 1 1/8 in. long, 7/16 in. crown 3 in. c. c. on all edges and 6 in. c. c. at other bearings 25/32 in. Fiberboard sheathing 1 3/4 in. galvanized roofing nail 8d common nail 16 ga. galvanized staples, 1 1/2 in. long, 7/16 crown 3 in. c. c. on all edges and 6 in. c. c. at other bearings 1/2 in. Gypsumboard sheathing 1 1/2 in. galvanized roofing nail 11 ga., 3/8 in. to 7/16 in. head 16 ga. galvanized staples, 1 1/2 in. long, 7/16 crown 4 in. c. c. on all edges and 8 in. c. c. at other bearings Note a. For nailing of plywood, see reference standard RS 10-9. CEILING JOIST NAILING TO EVERY RAFTER (Number of 16d nails) Slope of Roof 4/12 5/12 6/12 7/12 9/12 12/12 Rafter Spacing, o.c. (in.) 16 24 16 24 16 24 16 24 16 24 16 24 Width of building Up to 24 ft. 5 8 4 7 3 5 3 4 3 3 3 3 24 to 30 ft. 7 11 6 9 4 7 3 6 3 4 3 3

NYC Admin. Code § 27-624 Construction methods.

§ 27-624 Construction methods. (a) Fabrication. All timber shall be accurately cut and framed to a close fit in such a manner that the joints will have even bearing over the contact surfaces. Mortises shall be true to size for their full depth and tenons shall fit snugly. No shimming in joints, or open joints, shall be permitted. (b) Erection. (1) ASSEMBLY. Joints shall have a tight fit. Fasteners shall be installed in a manner that will not damage the wood. End compression joints shall be brought to full bearing. All framework shall be carried up true and plumb. (2) TEMPORARY CONNECTIONS. As erection progresses, the work shall be bolted, or nailed as necessary, to resist all dead load, wind, and erection stresses. (3) ALIGNMENT. The structure shall be properly aligned before final tightening of the connections.

Source: City of New York, Charter, Administrative Code and Rules (American Legal Publishing XML export, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCadmin/0-0-0-50979Fetched: 10/24/2026