How is steel deck capacity determined for roof and floor applications?

Steel deck capacity is determined by three limit states: bending, shear, and deflection, with bending typically governing for standard roof deck spans. The Steel Deck Institute (SDI) publishes load tables based on full-scale testing and the effective width method of AISI S100 (North American Specification for Cold-Formed Steel Structural Members). The bending capacity depends on: (1) Deck profile — deeper decks carry more load at longer spans because section modulus increases with depth². A 3-inch deep deck has approximately 4× the bending capacity of a 1.5-inch deck of the same gauge. (2) Gauge (thickness) — moving from 22 ga (0.0295 in) to 20 ga (0.0358 in) increases capacity by approximately 40% because moment of inertia is proportional to t. (3) Span condition — multi-span (3+) decks carry 20-40% more load than single-span because the positive moment coefficient reduces from wL²/8 to wL²/11.4 (a 42% reduction), while the negative moment over interior supports (wL²/8 for 2-span, wL²/11.4 for 3+ span) governs at the support. (4) Yield strength — standard deck steel is 33-50 ksi yield (typically ASTM A653 SS Grade 33 or Grade 50). Grade 50 deck provides 50/33 = 52% more bending capacity. The SDI Diaphragm Design Manual provides the shear diaphragm capacity, which is a function of the weld or screw pattern connecting the deck to the supporting steel. A typical 1.5B 22-gauge roof deck spanning 5 ft (3-span) with Grade 33 steel carries approximately 70 psf total load (bending-controlled), with shear capacity typically exceeding 300 plf (not controlling). For composite floor deck (deck + concrete slab acting compositely via embossments), the deck serves dual purposes: permanent formwork during construction (must support wet concrete weight, typically 50-60 psf for 4.5-inch slab), and tensile reinforcement for the composite slab in the final condition.

What is the difference between composite and non-composite steel floor deck?

Non-composite steel floor deck (form deck) functions only as permanent formwork to support the wet concrete during construction. After the concrete cures, the deck contributes nothing to the slab's flexural strength — the reinforced concrete slab carries all loads. Non-composite deck is typically 2-3 inches deep, 22-26 gauge, with a simple trapezoidal or re-entrant profile. The deck is designed for the wet concrete load (typically 0.75-1.0× wet concrete weight plus construction live load of 20 psf per AISC 360 and OSHA). After curing, the slab is reinforced with welded wire fabric (WWF) or rebar for temperature and shrinkage plus any required flexural reinforcement. Composite steel floor deck has embossments (raised deformations) rolled into the deck profile that mechanically interlock with the cured concrete, enabling composite action: the concrete slab carries compression and the steel deck carries tension, acting as external tensile reinforcement. Composite deck eliminates most bottom slab reinforcement (except for fire rating requirements and negative moment regions over girders). The composite slab strength depends on the shear bond capacity between the deck embossments and the concrete — this is determined by full-scale bending tests per SDI T-CD and ANSI/SDI C-2017, not by calculation from first principles. Key differences in design: composite deck can span 10-18 ft (vs 5-10 ft for non-composite), composite slab thickness is typically 4.5-6.5 inches total (3-4.5 inches concrete above deck), composite slabs have longer fire ratings (1-3 hours unprotected), and composite slabs are 15-25% heavier but eliminate the bottom rebar cage entirely. The yield strength of composite deck steel is typically 50-80 ksi to maximize the tensile contribution, vs 33-50 ksi for non-composite form deck.

How does the number of spans affect steel deck load capacity?

The number of continuous spans significantly affects deck load capacity because the bending moment coefficients change. Per SDI and AISI S100: Single span: M_max = wL²/8 (positive moment only, midspan). The deck acts as a simply-supported beam. Two-span: M_max (positive) = wL²/8 (at 0.375L from exterior support in each span); M_max (negative) = wL²/8 (over the interior support). The negative moment over the interior support governs design because the deck profile is not optimized for negative bending — the compression flange is the unbraced flat bottom of the deck, which may locally buckle. Three or more spans: M_max (positive) ≈ wL²/11.4 (at approximately 0.4L from exterior supports); M_max (negative) ≈ wL²/11.4 (over the first interior support), reducing to wL²/12 at interior supports away from the ends. The positive moment coefficient decreases from wL²/8 to wL²/11.4, a 42% reduction, which translates directly to ~42% more load capacity for the same deck section. However, SDI load tables account for the controlling condition at each span — for 3-span conditions, the controlling check is often the exterior span positive moment (wL²/11.4) or the first interior support negative moment (also wL²/11.4). The interior span positive moment (wL²/16) and interior supports (wL²/12) are not controlling. Practical design: most deck is installed as 3+ continuous spans because the cost of splicing at each support is offset by 30-40% longer span capability, reducing the number of support beams by 25-30%. Single-span deck is used only for short filler areas (skylights, openings, odd bay sizes). Two-span conditions should be avoided when possible because they give the worst of both worlds — negative moment governs at the support with wL²/8 (same as single span), but without the multi-span redistribution benefit of 3+ spans.

How are steel deck diaphragm loads transferred to the lateral force resisting system?

Steel roof and floor deck functions as a structural diaphragm, transferring lateral loads (wind, seismic) from the building's exterior to the lateral force resisting system (braced frames, shear walls, or moment frames). The diaphragm acts as a deep horizontal beam: the deck is the web resisting shear, and the perimeter steel members (edge angles, spandrel beams, or chord members) act as flanges resisting tension and compression. The diaphragm shear capacity is governed by the deck-to-structure connections — typically puddle welds (arc spot welds through the deck to the supporting steel below) or mechanical fasteners (screws, power-actuated fasteners). Per SDI Diaphragm Design Manual (DDM04): the nominal diaphragm shear strength S_n depends on the weld pattern. Common patterns: 36/7 pattern — welds at every support (36 inches spacing) and every other flute at the panel side laps (7 fasteners per panel width at each support). This gives S_n ≈ 2,000-4,000 plf for 22-gauge deck depending on panel profile and support thickness. 36/4 pattern (welds at every support, every third flute at side laps) — S_n ≈ 1,500-2,500 plf. The controlling diaphragm failure modes: (1) Weld shear failure — the puddle weld shears through the deck at the support (weld pull-out). (2) Panel buckling — the deck buckles in shear (similar to web shear buckling in a plate girder). This is typically the controlling mode for thin-gauge decks (26-24 ga) at longer spans. (3) Side-lap fastener failure — the screws or button punches connecting adjacent panels slip or tear, reducing the diaphragm's in-plane shear stiffness before ultimate failure. (4) Chord failure — the perimeter chord member yields in tension or buckles in compression. For seismic design (ASCE 7 Section 12.10), the diaphragm must remain elastic under the design seismic force, and the diaphragm deflection must not exceed 2× the allowable story drift. For a typical 200 ft × 300 ft roof, the diaphragm shear near the perimeter braced frames is approximately V/L = (wind pressure × building width/2) / building length = (30 psf × 150 ft) / 2 / 300 ft = 7.5 kip/ft (375 plf), well within the capacity of 22-gauge deck with 36/7 welds (~2,000 plf).

What are typical steel deck deflection limits and how are they checked?

Steel deck deflection limits are governed by the SDI and the IBC: (1) Roof deck under total load (dead + live/snow): L/240 maximum for decks supporting flexible finishes, L/180 for decks without brittle finishes. For a 6 ft span: L/240 = 0.30 in, L/180 = 0.40 in. (2) Roof deck under live load only (for ponding check): L/240, with an additional requirement that the deck slope must be at least 1/4 inch per foot (2%) after deflection to ensure positive drainage. Ponding is a progressive failure mode — water accumulates in the deflected bay, adding weight, causing more deflection, accumulating more water, until the deck collapses. Per IBC 1611, the deck must have adequate stiffness to prevent ponding instability, typically checked by ensuring the deck stiffness parameter exceeds a critical value. (3) Floor deck under live load: L/360 to avoid perceptible vibration. For a 10 ft span: L/360 = 0.33 in. (4) Floor deck under total load: L/240 per IBC Table 1604.3. (5) Construction-stage deflection (wet concrete on form deck): L/180, or the lesser of 3/4 inch per AISC 360, to avoid excessive concrete ponding during placement. The deck moment of inertia I_e (effective) may be reduced for deflection calculation because the deck may be partially yielded at service loads. SDI load tables use the gross moment of inertia I_g multiplied by a serviceability factor to account for this. For roof deck, ponding instability is the most dangerous failure mode — it caused the Hartford Civic Center roof collapse (1978). The deck must have enough stiffness such that the deflection from a unit water load does not exceed the incremental depth that accumulates from that deflection — essentially, the deck must be steeper after deflection than the water that accumulates.

What is Steel Deck Calculator — Metal Deck Design?

Steel roof and floor deck design checks per SDI standards. Bending, shear, and deflection for composite and non-composite metal deck configurations.

Steel Deck Calculator

Quick answer: A 1.5-inch deep, 22-gauge (0.0295 in) galvanized roof deck spanning 5 ft in a 3-span condition can carry approximately 70 psf total load (bending governs). Switching to 20-gauge (0.0358 in) increases capacity to about 100 psf. A 2-inch composite floor deck (22 ga) with 4.5 inches of lightweight concrete spanning 10 ft typically achieves 140-200 psf allowable superimposed load. Use the calculator below for exact capacities per SDI standards.

Common Steel Deck Profiles

Profile	Depth (in)	Type	Typical Gage	Typical Span Range
1.5B (narrow rib)	1.5	Roof deck	22-26	4-8 ft
1.5W (wide rib)	1.5	Roof deck	22-26	4-8 ft
2.0N	2.0	Floor form deck	22-26	5-10 ft
3.0N	3.0	Composite floor deck	18-22	8-15 ft
1.5 inch composite	1.5	Floor deck w/ re-entrants	22-26	6-12 ft
2 inch composite	2.0	Floor deck w/ re-entrants	22-26	7-14 ft
3 inch composite	3.0	Deep composite deck	18-22	10-18 ft

Gage Thickness Reference

Gage	Thickness (in)	Weight (psf, bare)	Relative Cost
26	0.0179	0.75	Lowest
24	0.0239	1.00	Low
22	0.0295	1.23	Medium
20	0.0358	1.49	Medium-High
18	0.0474	1.98	High

Span Condition Effect on Capacity

The number of continuous spans significantly affects deck capacity:

Span Condition	Moment Coefficient	Relative Capacity vs Single Span
Single span	wL^2/8	1.0x (baseline)
Double span	wL^2/8 (negative at support)	~1.0x (negative moment governs)
Triple span (3+)	wL^2/11.4 (positive)	~1.4x (positive moment governs)

Multi-span (3+) conditions carry about 20-40% more load than single span due to reduced positive moment. However, negative moment at interior supports must also be checked.

Composite vs. Non-Composite Deck

Composite deck has embossments that bond to the concrete, so the deck acts as bottom reinforcement. Eliminates bottom rebar. Used for floor systems.

Non-composite (form) deck is permanent formwork only. Concrete slab is designed as reinforced concrete with conventional rebar. Used where fire rating requires minimum concrete cover over the deck.

Deflection Limits

Construction (before concrete): L/180 or 3/4 inch, whichever is less (SDI/IBC)
Floor composite slab (live load): L/360
Roof deck (total load): L/240
Roof deck (live load): L/360

How the Calculator Works

The calculator uses effective section properties per AISI S100 for the specified deck profile. Positive and negative moment capacities are checked for multi-span conditions. Shear capacity includes web shear and web crippling at supports. Deflection is computed using standard beam formulas.

Worked Example — Roof Deck Selection

Problem: Select a roof deck for a 6 ft span in a 3-span continuous condition. Total load = 50 psf (dead + live). Deflection limit: L/240.

Step 1 — Required moment capacity

Span: L = 6 ft = 72 in
Load: w = 50 psf × 1 ft tributary = 50 lb/ft per foot of width

For 3-span continuous, positive moment coefficient = wL²/11.4:
Mu = 50 × 6² / 11.4 = 158 lb-ft/ft = 1,894 lb-in/ft

With LRFD factored load (1.2D + 1.6L), assume D = 10 psf, L = 40 psf:
wu = 1.2 × 10 + 1.6 × 40 = 76 psf
Mu = 76 × 36 / 11.4 = 240 lb-ft/ft = 2,880 lb-in/ft

Step 2 — Select deck profile

Try 1.5B (narrow rib), 22 gauge (t = 0.0295 in)
Effective section properties (from manufacturer's table):
  Positive Ma (allowable) ≈ 2,500 lb-in/ft for 22 ga, 3-span
  Negative Ma ≈ 2,200 lb-in/ft

Service moment: 1,894 lb-in/ft < 2,500 → OK (positive)
Negative moment = wL²/9 = 50 × 36 / 9 = 200 lb-ft/ft = 2,400 lb-in/ft
2,400 < 2,500 → Need to check... 2,400 > 2,200 negative capacity → MARGINAL

Upgrade to 22 ga 1.5W (wide rib):
  Positive Ma ≈ 3,200 lb-in/ft
  Negative Ma ≈ 2,800 lb-in/ft
  → Both OK ✓

Step 3 — Deflection check

Service load: w = 50 psf
I_eff ≈ 0.180 in⁴/ft (typical for 1.5W, 22 ga)
E = 29,500 ksi

Δ = 5wL⁴ / (384EI) = 5 × 50/12 × 72⁴ / (384 × 29,500,000 × 0.180)
Δ = 5 × 4.17 × 26,873,856 / (2,030,400,000)
Δ = 0.276 in

L/240 = 72/240 = 0.30 in → 0.276 < 0.30 ✓

The 1.5W 22-gauge roof deck in a 3-span condition works for this 6 ft span at 50 psf total load.

Worked Example — Composite Floor Deck

Problem: A composite floor deck spans 10 ft between beams. The slab consists of 2-inch composite deck with 4.5 inches of normal-weight concrete (total slab depth = 6.5 inches). Superimposed dead load = 25 psf, live load = 100 psf. Determine the allowable span.

Step 1 — Slab weight

2" composite deck (22 ga): 1.23 psf
4.5" normal concrete: 4.5/12 × 150 = 56.25 psf
Total slab weight: 57.5 psf
Total dead load: 57.5 + 25 = 82.5 psf

Step 2 — Construction stage (before concrete cures)

Wet concrete + deck: 57.5 psf
Construction load: 20 psf (SDI minimum)
Total: 77.5 psf

For 2" deck, 22 ga, 3-span:
Construction span capacity ≈ 8-10 ft (bending governs)
→ 10 ft span is at the upper limit. May require shoring during construction.

Step 3 — Composite slab capacity (after concrete cures)

Total slab: 6.5" total depth, 2" deck acting as reinforcement
Superimposed load: 25 + 100 = 125 psf

Typical composite slab capacity (2" deck, 4.5" NW concrete, #6 mesh):
  10 ft span: 130-180 psf superimposed (varies by manufacturer)

125 psf < 140 psf (conservative estimate) → OK ✓

For the specific capacity, use the manufacturer's load table for the
exact deck profile and concrete strength.

Connection and Fastening Requirements

Deck-to-structure connections

Connection Type	Fastener	Spacing	Requirement
Deck to steel beam (arc weld)	5/8" arc spot weld	12" max at supports	Weld washer for t < 0.028 in
Deck to steel beam (screw)	#12 self-drilling screw	12" max at supports	Min 3 per sheet width
Deck to steel beam (powder actuated)	PAF pin	12" max at supports	Check diaphragm capacity
Side laps (screw)	#10 self-drilling screw	24" to 36" max	Prevents buckling
Side laps (weld)	1" seam weld	36" max	For high-diaphragm demand

Minimum support bearing

Condition	Minimum End Bearing	Minimum Interior Bearing
1.5" deck	1.5 in	3 in
2" deck	1.5 in	3 in
3" deck	2.0 in	4 in

Shear stud requirements (composite deck)

For composite beam design (AISC Chapter I):
  Number of studs = Vh / Qn

  Vh = horizontal shear force = min(0.85f'c × Ac, As × Fy)
  Qn = nominal shear strength of one stud per AISC Table 3-21

  Minimum: 1 stud per flute (per rib) for deck ribs perpendicular to beam
  Stud diameter: ≤ 2.5 × base metal thickness (unless welded through deck)

  Typical: 3/4" diameter × 4-3/8" headed studs through 2" composite deck

Steel Deck Diaphragm Capacity — Quick Reference

Diaphragm capacity depends on the deck profile, gauge, connection type, and span condition. Values below are typical ranges for seismic design.

Profile	Gauge	Arc Weld (lb/ft)	Screw (lb/ft)	Typical Application
1.5B	22	300-400	250-350	Light roof diaphragm
1.5W	22	400-550	350-500	Standard roof diaphragm
1.5W	20	500-700	450-650	Heavy roof diaphragm
2.0 composite	22	350-500	300-450	Floor diaphragm
3.0 composite	20	600-900	500-800	Heavy floor diaphragm

Values are nominal shear strength per foot of deck width. Actual capacity must be verified with manufacturer's ICC-ES report for the specific profile and connection pattern.

Common Deck-to-Beam Connection Details

The following table summarizes the standard connection details for attaching steel deck to supporting steel framing. Proper selection depends on the deck profile, gauge, loading, and diaphragm shear requirements.

Connection Detail	Fastener Type	Deck Gauge Range	Fastener Size	Weld Time (sec)	Typical Capacity (lb/fastener)	Best Use
Arc spot weld, no washer	Weld stud	22 ga and thicker	5/8" dia minimum	3-5	1,800-2,500	Standard roof and floor deck
Arc spot weld, weld washer	Weld stud + washer	24 ga and thinner	5/8" dia minimum	5-8	1,200-1,800	Thin deck (26 ga, 24 ga)
Fillet weld (perimeter)	Shielded arc weld	20 ga and thicker	1" min length	8-12 per weld	1,500-2,200	Heavy floor deck, seismic
Self-drilling screw	#12 hex-head screw	22-26 ga	#12 x 1-1/4"	N/A	600-1,000	Screw-down roof deck
Self-drilling screw	#14 hex-head screw	18-22 ga	#14 x 1"	N/A	800-1,200	Heavy floor deck
Powder-actuated fastener	PAF drive pin	22-26 ga	0.145" dia pin	N/A	400-700	Concrete-filled deck, retrofit
Side lap screw	#10 pancake-head	All gauges	#10 x 3/4"	N/A	200-400 (shear)	Side lap stitch, all profiles
Side lap weld	1" seam weld	20 ga+	1" long	4-6 per weld	400-600 (shear)	High-diaphragm-demand applications

Key notes on connection details:

Arc spot welds are the most common and economical connection for deck-to-steel-beam attachment. They require access to the top flange and are not suitable for deck over concrete or wood supports.
Weld washers (also called "ferrule washers" or "burn-through washers") are required when the deck thickness is less than 0.028 inches (thinner than 22 gauge) to prevent burn-through during welding.
Screw attachments allow installation from the top side without welding equipment, making them preferred for field modifications and small projects.
Powder-actuated fasteners are used primarily for retrofit or when welding is impractical. Their capacity is lower than arc spot welds, so closer spacing may be required.
Side lap connections (screws or welds) connect adjacent deck sheets along their longitudinal edges. They are critical for diaphragm shear transfer and preventing panel separation under load. Typical spacing is 24 to 36 inches on center, but may need to be as tight as 12 inches for high seismic or wind diaphragm demands.

Frequently Asked Questions

What is the difference between composite and non-composite metal deck? Composite metal deck has embossments or other shear transfer features that bond the deck to the concrete fill, creating a reinforced composite slab where the deck acts as the bottom reinforcement. Non-composite (form) deck serves only as formwork for the concrete during construction; after the concrete cures, the slab strength is determined by conventional reinforced concrete design. Composite deck is more economical for floor systems because it eliminates the need for bottom reinforcement bars.

How does the number of spans affect deck capacity? Multi-span (continuous) deck has higher load capacity than single-span deck because the negative moment at interior supports partially offsets the positive moment at midspan, resulting in lower maximum moment for the same load. A three-span condition typically carries about 20% more load than a single span of the same length. However, the negative moment at supports may govern for certain load patterns, so the design must check all critical sections.

What deflection limits apply to metal deck? SDI and IBC typically limit the deflection of metal deck under construction loads (before concrete is placed) to L/180 or 3/4 inch, whichever is less. For composite floor deck under service loads, the concrete slab deflection limit is typically L/360 for live load. For roof deck, the deflection limit is typically L/240 for total load. These limits prevent ponding on roofs and ensure adequate flatness for floor finishes.

What is the difference between narrow rib and wide rib deck? Narrow rib (NR or B) profiles have shorter flutes (about 1.5 inch width) providing more bearing surface for the concrete but less space for reinforcement and services. Wide rib (WR or W) profiles have wider flutes (about 2.5 inch width) allowing more room for reinforcing bars, electrical conduit, and mechanical penetrations. Wide rib profiles generally have higher moment capacity due to the wider compression flange, but may require more concrete fill to achieve the same fire rating.

How do I specify metal deck on construction drawings? Deck specifications should include: (1) deck type (e.g., 1.5B22 for 1.5-inch deep, narrow rib, 22 gauge), (2) galvanized coating weight (G60 or G90), (3) span condition (single, double, or triple+), (4) connection type and spacing (arc weld, screw, or PAF), (5) side lap fastener spacing, and (6) any special requirements like diaphragm capacity or acoustic insulation. Always reference the SDI Standards and the specific manufacturer's catalog for non-standard profiles.

What is the typical cost of steel deck per square foot? As of 2026, steel roof deck costs approximately $3-6 per square foot installed (depending on gauge and profile), while composite floor deck costs approximately $4-8 per square foot. The cost of concrete fill adds $5-10 per square foot depending on slab thickness and concrete type. Total composite floor system cost (deck + concrete + reinforcement + studs) typically runs $15-25 per square foot, making it competitive with flat-plate concrete construction for spans over 20 feet.

How does galvanizing affect deck corrosion resistance, and when is G60 versus G90 required? Galvanized steel deck receives a zinc coating specified by weight: G60 means 0.60 oz/ft² of zinc (total both sides) and G90 means 0.90 oz/ft². G60 is the standard specification for most roof and floor deck applications in enclosed buildings where the deck is protected from weather. G90 provides approximately 50% more zinc and is specified for exposed or humid environments such as parking structures, industrial buildings with chemical exposure, or coastal locations within 1 mile of saltwater. For highly corrosive environments, stainless steel deck (Type 304 or 316) is used at significantly higher cost. Galvanized coating thickness is approximately 0.0008 inches per side for G60 and 0.0012 inches per side for G90. The coating adds roughly 2-4% to the bare steel weight, which is negligible for structural calculations but should be noted in material specifications.

What are acoustic deck properties, and when should acoustic metal deck be specified? Acoustic metal deck (also called acoustical deck) has perforated webs or flanges with a fiberglass or mineral wool sound-absorbing pad bonded to the interior surface. The perforations allow sound energy to enter the absorptive material, reducing sound transmission by 3-8 dB compared to solid deck of the same profile. Typical Noise Reduction Coefficient (NRC) values range from 0.60 to 0.85 for acoustic deck versus 0.05-0.10 for standard solid deck. Acoustic deck is specified in gymnasiums, auditoriums, natatoriums, open-plan offices, and mechanical equipment rooms where reverberation control is important. The acoustic perforations do not significantly reduce the structural capacity of the deck when the perforation pattern follows the manufacturer's ICC-ES evaluated pattern (typically 20-30% open area in the web only, not the flanges). Acoustic deck costs approximately 30-50% more than standard deck and is available in limited profiles (typically 1.5B, 1.5W, and 3-inch composite).

What are the side lap fastening requirements for steel deck diaphragm design? Side lap fasteners connect adjacent deck sheets along their longitudinal edges and are essential for diaphragm shear transfer and preventing panel separation. The required spacing depends on the diaphragm shear demand, deck profile, gauge, and the type of structural connection at supports. For typical roof deck diaphragms with moderate wind loads, side lap fasteners at 36 inches on center are sufficient. For high seismic or wind diaphragm demands, spacing may need to be reduced to 24 inches or even 12 inches on center. The SDI Diaphragm Design Manual provides tables relating side lap fastener spacing to diaphragm shear capacity. Side laps can be fastened with #10 self-drilling screws (most common), 1-inch seam welds (highest capacity), or proprietary clinch tools. For spans over 8 feet, side lap connections are also important for preventing visible waviness ("oil-canning") in the flat areas of the deck between flutes.

What is the typical deck installation sequence for a multi-story steel building? The steel deck installation sequence follows the steel erection sequence and is closely coordinated with safety planning. The typical sequence is: (1) Erect the steel framing for a floor, completing all moment connections, splices, and bracing for that tier. (2) Install safety cables and perimeter fall protection on the completed framing. (3) Place metal deck sheets starting at one corner, progressing across the bay. Sheets are placed with the male edge overlapping the female edge of the previously placed sheet. (4) Attach deck to the steel beams at all supports using arc spot welds or screws, typically at 12 inches on center maximum. (5) Install side lap fasteners at the specified spacing. (6) Install shear studs through the deck into the beam top flanges (for composite construction). (7) Place welded wire reinforcement (if required). (8) Pour concrete. This sequence repeats floor by floor, typically with 2-3 floors of steel erected ahead of the deck installation to maintain safe working platforms. OSHA requires that deck be installed and attached before workers can access the area, and unattached deck sheets are considered an unstable walking surface.

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