Does a 1 x 3/16 inch stair tread meet OSHA requirements?

Yes. OSHA 1910.25 requires stairs to support 1000 lb or 5 times the anticipated load. A 36 inch welded 1 x 3/16 inch tread in 19-W-4 pattern provides about 480 lb mid-span on a single bearing bar; the full 9-bar tread delivers well above 4000 lb mid-span.

What is the standard stair tread depth?

Typical commercial depth is 9-7/8 inch (250 mm) or 11-1/8 inch (283 mm) measured nose-to-nose. Both use the same bearing bar with different bar counts.

Do I need serrated stair treads?

Serrated bearing bars are required for outdoor, wet, oily, or ADA-sensitive applications. Smooth bars are acceptable for dry indoor conditions. Checker-plate nosing is standard on both.

Can stair treads be hot-dip galvanized?

Yes. Hot-dip galvanizing per ASTM A123 is applied after welding and drilling of carrier-plate holes. Nosing and carriers are galvanized together as an assembly.

What is the maximum stair tread length Wiberg can supply?

Standard lengths up to 72 inches (1830 mm). For longer spans, consider double bearing bar arrangement or heavy-duty 1-1/2 x 3/16 inch treads; confirm with Wiberg engineering.

Home Engineering Load Tables Stair Treads

Stair Tread Load Tables

Load and span data for stair tread products.

Design basis

Material: carbon steel, ASTM A1011, F_y = 36 ksi; also available in stainless 304/316 and aluminum 6061-T6.
Pattern: welded 19-W-4 with 1-3/16" (30 mm) bearing bar centers, 4" cross bars, checker-plate or serrated top.
Nosing: integral checker-plate (2" or 2-1/2" deep) welded across front edge for slip resistance and ADA / OSHA compliance.
Support: two end brackets / carrier plates, bolt or weld to stringers.
Design loads (IBC / OSHA 1910.25): 300 lb (1.33 kN) concentrated at mid-span and 100 psf (4.8 kPa) uniform — whichever governs.

Allowable concentrated midspan load — welded 19-W-4, 3/16" bar

Maximum allowable concentrated load (lb) applied at mid-span of a welded steel stair tread, per AISC ASD.
Bearing bar depth	24" (610 mm)	30" (760 mm)	36" (915 mm)	42" (1065 mm)	48" (1220 mm)
1" × 3/16"	720	580	480	410	360
1-1/4" × 3/16"	1120	900	750	640	560
1-1/2" × 3/16"	1620	1300	1080	925	810
1-3/4" × 3/16"	2200	1760	1470	1260	1100
2" × 3/16"	2880	2300	1920	1645	1440

Concentrated load applied at mid-span across a 4" × 4" contact area. All values exceed the 300 lb IBC / OSHA minimum by a wide margin; standard 1" × 3/16" treads are adequate for almost every commercial staircase.

Allowable uniform load — stair tread

Maximum allowable uniform load (psf) on a welded steel stair tread.
Bearing bar depth	24" (610 mm)	30" (760 mm)	36" (915 mm)	42" (1065 mm)	48" (1220 mm)
1" × 3/16"	440	280	195	143	110
1-1/4" × 3/16"	665	425	295	217	165
1-1/2" × 3/16"	930	595	415	305	235

Standard tread dimensions

Common stair tread depths (nose-to-nose) and typical bearing bar specification.
Tread depth (walk)	Typical bar & series	Nosing
8-3/4" (222 mm)	1" × 3/16" 19-W-4	1-1/2" checker-plate
9-7/8" (250 mm)	1" × 3/16" 19-W-4	1-1/2" checker-plate
11-1/8" (283 mm)	1-1/4" × 3/16" 19-W-4	2" checker-plate
11-15/16" (305 mm)	1-1/4" × 3/16" 19-W-4	2" checker-plate

FAQ — stair tread load tables

Does a 1" × 3/16" stair tread meet OSHA?: Yes. OSHA 1910.25 requires stairs to support 1,000 lb or 5× anticipated load. A 36" long 1" × 3/16" tread in 19-W-4 pattern provides ~480 lb mid-span on a single bearing bar; the full tread (9 bars) delivers well above 4,000 lb mid-span.
What is the standard stair tread width (depth)?: Typical commercial depth is 9-7/8" (250 mm) or 11-1/8" (283 mm) measured nose-to-nose. Both depths use the same bearing bar, different number of bearing bars.
Do I need serrated or smooth bearing bars?: Serrated (notched top edge) is required for outdoor, wet, oily, or ADA-sensitive applications. Smooth bars are acceptable for dry, indoor conditions. Checker-plate nosing is standard on both.
Can treads be galvanized after fabrication?: Yes. Hot-dip galvanizing per ASTM A123 is applied after welding and drilling of carrier-plate holes. Nosing and carriers are galvanized as an assembly.
What is the maximum tread length I can supply?: Standard lengths up to 72" (1830 mm). For longer spans consider double bearing bar arrangement or heavy-duty 1-1/2" × 3/16" treads; confirm with engineering.

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