UL 10A:2009 pdf download – Tin-Clad Fire Doors.
6.3 Boards shall not be less than 1 ft (305 mm) in length, with ends cut Square. Not more than two pieces shall be used in any continuous strip in any outside layer of a two-ply or three-ply core, nor more than three pieces in any middle layer strip ot a three-ply core, At least alternate strips in outside layers shall be full’length boards.
6.4 Outside layers in a three-ply core and one layer of a two-ply core shall be vertical, and the other layer horizontal.
6.5 The several boards in each layer and the ends of pieces of boards in strips shall make tighi jcints at edges and ends of boards.
66 When glass panels are supplied, the boards in the normally vertical layers bordering the sides of the panel opening shall be continuous from top to bottom of the door, and boards in the normally horizontal layer bordering the top or bottom of the panel opening shall be continuous from side-to-side of the door. The distance between the panel opening and the side of the door shall be not less than 7 in (178 mm), See Figure 6.2.
6.7 As an alternate to the general board arrangement described In 6.4, when glass panels are supplied and the panel opening is of such a size that the distance between the opening and the edges of the door is less than 2 ft (610 mm), all boards bordering the vertical edges of the opening have the option of being laid vertically and all boards bordering the horizontal edges of the opening have the option of being laid horizontally.
6.8 The top edge for a sliding door designed to close by gravity shall conform to an incline of 3/4 in per foot (63 mm/m).
6.9 The minimum face width of the top horizontal board of a core having the top edge Inclined shall be not less than 3 in (76 mm) at one end. See Figures 72 — 7.4.
7 NailIng of Cores
7.1 General
7,1.1 The boards shall be nailed so that the several layers are fastened tightly together, with the points of the nails turning back and clinching thoroughly in the face of the core and with no portion of the nails projecting beyond the surfaces of the core. See Figure 7.1.
8 Finished Cores
8.1 A finished three-ply core shall not be less than 2-1/4 in (57.2 mm) nor more than 2-518 in (66,7 mm) in thickness, and a finished two-ply core shall not be less than 1-1 in (38.1 mm) nor more than 1-3/4 in (44.5 mm) in thickness.
8.2 A finished three-ply core door which is less than 2-1/4 in (57.2 mm) thick as specified in 8.1 is to be marked in accordance with the schedule for two-ply doors.
8.3 The cores shall have true corners.
8.4 All edges shall be finished smooth and square. The meeting edges of swinging doors shall be square or beveled 1/4 in (6.4 mm) (not rabbeted).
9 Sizes of Steel Sections
9.1 Coated steel sections shall be not larger than 14- by 20-in (356- by 508-mm) size.
9.2 Corner sections shall not be over 14 in (356 mm) wide and of any length that avoids joints with edge sections coming under miter fold.
9.3 Edge sections (excepting cap sections) shall be of the same width as corner sections and of any convenient length.
9,4 Cap sections shall be of any convenient length and equal in wdth to thickness of core plus 3-1/2 in (89 mm).
10 Forming of Steel Sections
10.1 Turned edges of coated steel sections shall be parallel to cut edges. Turned up portions of all sections shall be of uniform width,
10.2 Face sections, exceptIng the face sections used In the row forming the closure, shall have one vertical edge turned 5/8 in (15.9 mm) and the other vertical edge doubled under 1-3/16 in (30 mm), and the doubled edge then turned up 5/8 in (15.9 mm) from cut edge as shown in Figure 10.1. Section A-B.
10.3 Face sections. excepting face sections forming top horizontal seams, shall have both horizontal edges turned 5/8 inch (15.9 mm) to lock with edge and other face sections shown in Figure 10.1. Section C-D.
10.4 Face sections forming top horizontal seams, excepting seams formed with a cap. shall have the lower horizontal edge turned 5/8 in (1 59 mm) to lock with other face sections. and the other horizontal edge doubled under 1-3116 In (30 mm) and the double edge then turned up 5/8 in (15.9 mm) from Cut edge.
10.5 Face sections forming top horizontal seams with a cap shall have both honzontal edges turned up 5/8 in (15.9 mm) so as to lock with cap and other face sections.