Walk onto any structural steel floor system in a commercial building project and you will find two fundamentally different welding operations happening within a few feet of each other: headed shear stud welding and deck attachment arc spot welding. Both are part of the composite floor system. Both involve structural welds. But they are governed by different AWS codes, require different WPS documents, and have different inspection acceptance criteria.
Mixing them up — assuming that a WPS and inspection program written for one applies to the other — is a common QC gap that produces nonconformance findings and audit failures.
The Two Welding Codes in a Composite Floor System
AWS D1.1, Structural Welding Code — Steel covers welding of structural steel members and connections. AWS D1.1 Clause 7 specifically addresses stud welding, including the headed shear connectors that transfer horizontal shear between the steel beam and the concrete slab in a composite system. Whether the studs are welded to the bare top flange or through the corrugated deck in a through-deck welding operation, Clause 7 governs.
AWS D1.3, Structural Welding Code — Sheet Steel covers welding where one or more of the base metals is thin sheet steel (generally less than 3/16 in thick, which encompasses virtually all corrugated composite floor decking). AWS D1.3 governs the arc spot welds and arc seam welds used to fasten the deck panels to the structural framing, and the flare-groove or flare-bevel welds at deck sidelap conditions.
The composite floor system therefore sits at the intersection of both codes. Getting the boundary right — and building separate WPS and inspection programs for each domain — is the QC manager's responsibility before the deck crew arrives on site.
For background on AWS D1.3 sheet steel welding in general, see AWS D1.3 cold-formed sheet steel WPS requirements.
AWS D1.1 Clause 7: Headed Shear Stud Welding
Clause 7 of AWS D1.1 covers the welding of headed shear connectors using the stud welding process (SW). The stud welding process uses a drawn arc method where the stud is held against the base metal by a stud gun, an arc is drawn, the stud is plunged, and the molten pool solidifies into a full-base fillet.
WPS requirements under D1.1 Clause 7. The welding procedure for stud welding must be qualified. AWS D1.1 establishes stud welding as a prequalified process with defined welding parameter ranges, but the fabricator must demonstrate through pre-production testing that the stud welding system produces conforming welds before production begins. The pre-production test is typically a bend test on studs welded to representative base metal in the same position and through-deck configuration as production.
Through-deck stud welding. Many composite systems use through-deck stud welding, where the stud gun fires the stud through the deck sheet and into the beam flange below without pre-punching the deck. This configuration is within the scope of D1.1 Clause 7, but the WPS must account for the through-deck condition, and pre-production testing must replicate it. The deck profile, gauge, and coating (bare, galvanized, or painted) affect stud weld quality and must be reflected in the WPS.
Visual acceptance criteria. D1.1 Clause 7 visual criteria require that the completed stud show a full 360-degree flash around the base and that the stud can withstand a specified bend test without fracturing at the weld. A stud that is struck with a hammer and bent 30 degrees must spring back without cracking is the classic field verification.
For complete coverage of D1.1 stud welding requirements, see stud welding WPS and qualification under AWS D1.1 Clause 7.
AWS D1.3: Deck Attachment Arc Spot Welds
Once the deck sheets are laid on the framing, the deck attachment crew welds the deck to the structural steel through arc spot welds — sometimes called puddle welds in older specifications. These welds are made through the thin deck sheet (typically 20 to 22 gauge galvanized steel, roughly 0.033 to 0.036 in thick) into the thicker structural steel framing below. The resulting weld fuses the thin deck to the heavier structural member.
AWS D1.3 scope. AWS D1.3 was written specifically for this class of welding. The code addresses the fundamental challenge: one base metal is very thin (the deck) and one is significantly thicker (the beam or joist), requiring process control to avoid burning through the thin material while achieving adequate fusion in the heavier section.
WPS requirements under D1.3. A WPS is required for arc spot welds under D1.3. The WPS must document:
- The welding process (GMAW or FCAW for arc spot welds; SMAW for flare welds if used).
- The deck base metal specification, gauge, and coating type.
- The structural steel base metal specification and thickness range.
- Electrode classification and diameter.
- Shielding gas type and flow rate for GMAW.
- Current, voltage, and dwell time (for arc spot welding, dwell time controls the weld nugget size and penetration).
- Position (arc spot welds are typically made in the flat position; deck may also require overhead welds at underside conditions).
The prequalified path under AWS D1.3 is available for certain combinations, but the qualifier criteria — including base metal specifications, process, and electrode — must all be satisfied.
Acceptance criteria for arc spot welds. Visual acceptance under D1.3 requires a minimum visible weld diameter and a maximum amount of undercut or cracks. Unlike D1.1 stud welding, D1.3 arc spot welds are not typically subjected to destructive pull tests in routine production (though proof testing can be specified). The CWI performing D1.3 inspection must be calibrated to the D1.3 acceptance criteria, which differ from D1.1 visual criteria for groove or fillet welds.
Sidelap welds. At the longitudinal sidelaps where two deck sheets overlap, a flare-bevel groove weld is commonly used to stitch adjacent panels. These welds also fall under AWS D1.3. The WPS must cover this joint configuration separately from the arc spot weld WPS if the process or parameters differ.
Galvanized Deck: A WPS Complication for Both Codes
Virtually all floor decking is galvanized — coated with zinc for corrosion protection during construction. Zinc burns off during welding, producing zinc oxide fumes that are toxic and that can cause porosity in the weld if not managed. The WPS must acknowledge the galvanized condition of the deck.
Under D1.3, the galvanized coating on the deck is a known and expected base metal condition. The code addresses it, and the WPS parameters should be selected to account for the coating burn-off and the potential for porosity beneath the weld surface.
Under D1.1 Clause 7 for through-deck stud welding, the through-deck condition with a galvanized deck requires that the welding parameters and pre-production testing reflect the actual galvanized deck condition in production. Running pre-production tests on bare steel or a different deck gauge than what is used in production is a common and costly mistake.
For broader coverage of welding through coated steel, the considerations in welding through zinc-coated and primer-coated steel apply to both D1.1 and D1.3 applications.
Inspection Authority and QC Documentation
Special inspection requirements. Under IBC and most project specifications, stud welding (D1.1 Clause 7) is a special inspection item. The special inspector must observe stud installation and conduct or witness the pre-production testing. Deck attachment arc spot welds under D1.3 may or may not be designated as special inspection depending on the project structural notes and local building department requirements.
Separate inspection programs. Because D1.1 and D1.3 have different acceptance criteria, different test requirements, and different documentation formats, the CWI managing floor deck should maintain separate inspection records for:
- D1.1 stud welding: pre-production test results, production observation logs, bend test records.
- D1.3 deck attachment: WPS documentation, production observation, visual inspection results for arc spot and sidelap welds.
CWI scope. A CWI certified by AWS is generally qualified to inspect under both codes, but must be familiar with the specific criteria in each. The acceptance criteria for a D1.3 arc spot weld are not the same as the fillet weld criteria from D1.1, and applying the wrong standard is an inspection error. Before deploying a CWI to inspect floor deck, confirm they have reviewed the relevant D1.3 acceptance criteria.
For NDE and inspection method selection across multi-code projects, see NDE method selection across structural welding applications.
Building a Compliant WPS Program for Composite Floor Systems
A practical WPS program for a composite floor system includes at minimum:
- D1.1 Clause 7 stud welding WPS — listing stud diameter, base metal specifications, deck gauge and profile for through-deck conditions, pre-production test requirements.
- D1.3 arc spot weld WPS — covering the deck gauge, structural steel thickness range, electrode, position, and dwell time for the flat puddle weld.
- D1.3 sidelap/flare-bevel weld WPS — if sidelap welds are specified by the structural engineer.
Getting this separation correct before pre-construction QC meetings, and ensuring the special inspection program references both codes accurately, prevents the kind of submittal revisions and nonconformance reports that delay a steel erection schedule.
Manage all your WPS documents — D1.1 and D1.3 — in one audit-ready system.