N.Y.C. Admin. Code § 27-623: § 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