Structural · 11 checks

Metal Decking & Shear Studs
QA inspection checklist

Metal decking and through-deck stud welding quality audit.

Every check below carries what good looks like, when it passes, the standard it comes from and the defects that usually fail it. That guidance is what turns a tick-box into an inspection.

Decking Installation

  1. 1.
    Deck gauge, profile and material match the drawing
    What to look forDeck profile (e.g. re-entrant or trapezoidal) and gauge thickness match the structural drawing and decking schedule. Material certificate confirms coating (galvanised) and grade.
    Acceptable whenDeck profile and gauge per the decking layout drawing, tolerance per BS EN 1090-4. Galvanising coating mass per BS EN 10346, minimum Z275 typical for internal use.
    StandardBS EN 1090-4:2018, Technical requirements for steel and aluminium structural components, cold-formed. BS EN 10346, Continuously hot-dip coated steel.
    Common defectsWrong gauge delivered, thinner than specifiedProfile depth does not match the drawingCoating mass certificate missingDeck damaged in transit, dented pans
  2. 2.
    Minimum bearing onto supporting steelwork achieved
    Record: Bearing (mm)
    What to look forDeck ends land on the supporting beam or wall with the minimum bearing shown on the drawing, typically 50 mm end bearing. No deck end unsupported or bearing on a damaged flange.
    Acceptable whenBearing per the decking manufacturer's design and BS EN 1090-4, typically minimum 50 mm at end supports. No gap between deck soffit and beam flange greater than manufacturer tolerance.
    StandardBS EN 1090-4:2018. SCI P300, Composite Slabs and Beams using Steel Decking.
    Common defectsBearing less than the minimum at an end supportDeck sitting on distorted or out-of-tolerance steelworkGap under deck packed incorrectly or not at allBearing measured only at one point, not checked along the run
  3. 3.
    Deck fixed to supports with correct fixing type and spacing
    What to look forShot-fired pins, self-drilling screws or welded studs used as specified, at the centres shown on the fixing schedule. Fixing type matches the steel thickness, avoiding under- or over-penetration on shot-fired pins.
    Acceptable whenFixing type, size and spacing per the decking manufacturer's fixing schedule and BS EN 1090-4. Pull-out/shear capacity of the fixing matches the diaphragm design.
    StandardBS EN 1090-4:2018. Manufacturer fixing schedule. SCI P300.
    Common defectsFixing centres wider than the scheduleWrong cartridge strength for shot-fired pins causing under- or over-driveFixings missed at deck endsFixing type substituted without checking capacity
  4. 4.
    Side laps and end laps correctly nested and fixed
    What to look forSide laps of adjacent sheets correctly nested, interlocking profile engaged, along the full length. Fixed at the centres on the schedule, typically screwed or crimped at intervals.
    Acceptable whenSide lap fixing per manufacturer spacing, full engagement of the interlocking profile along the lap. No gap in the lap that would allow wet concrete to leak through during the pour.
    StandardSCI P300. Manufacturer installation guide.
    Common defectsSide lap not fully engaged, gap along the joinLap fixings missed or too widely spacedEnd laps not overlapping the minimum distanceConcrete leakage through an unclosed lap during the pour
  5. 5.
    Edge trim installed at all open edges and penetrations
    What to look forEdge trim fitted at slab perimeters and upstands, fixed at the centres specified, joints lapped and sealed to prevent concrete loss during the pour.
    Acceptable whenEdge trim per the decking layout drawing, fixed per manufacturer spacing, capable of retaining wet concrete without deflection or leakage during the pour.
    StandardSCI P300. Manufacturer installation guide.
    Common defectsEdge trim missing at a penetrationTrim joints not lapped, concrete leaks throughTrim under-fixed and deflects under pour pressureTrim height insufficient for the slab depth
  6. 6.
    Temporary propping installed where the design requires it
    What to look forProps under the deck at the centres and locations shown on the design where the deck span exceeds the unpropped capacity. Props on sole plates on a stable surface.
    Acceptable whenPropping per the decking design where spans exceed the unpropped span table for the deck profile and gauge. Props not struck until the concrete has reached the specified strength.
    StandardSCI P300. BS EN 1994-1-1 (Eurocode 4, composite construction).
    Common defectsPropping omitted where the span requires itProps not on a stable baseProps struck before concrete reaches design strengthProp spacing wider than the design

Stud Welding & Testing

  1. 7.
    Stud welding set correctly configured for the stud size and deck thickness
    What to look forWeld current, time and lift set per the stud manufacturer's parameters for the stud diameter and combined steel/deck thickness. Set calibrated and log of settings kept.
    Acceptable whenParameters per manufacturer data sheet for the stud diameter and total thickness being welded through. Settings verified at the start of the shift and after any equipment change.
    StandardBS EN ISO 14555:2017, Arc stud welding of metallic materials. Manufacturer welding parameters.
    Common defectsParameters not adjusted for a deck thickness changeNo record of settings usedWrong ferrule for the stud diameterWelding through excessive galvanising without adjustment
  2. 8.
    Stud welding operative trained and competent on the equipment
    What to look forOperative holds evidence of training on the specific stud welding equipment and process being used. Toolbox talk covers the parameters for the job.
    Acceptable whenOperative competence recorded per BS EN ISO 14555 requirements for the welding procedure. Training current and specific to through-deck stud welding, not just general welding.
    StandardBS EN ISO 14555:2017. Project quality plan.
    Common defectsNo training record for the specific processOperative unfamiliar with the parameter settingsNo supervision for a newly trained operativeTraining record out of date
  3. 9.
    Bend test carried out at the start of the shift and after parameter changes
    Record: Bend angle (degrees)
    What to look forSample stud bent to the specified angle using a hammer or bend tool without fracture at the weld. Test carried out on a stud representative of the day's production before welding proceeds at scale.
    Acceptable whenPer BS EN ISO 14555: bend test stud deflected to 15° (or per project specification) without weld fracture. Test repeated after every change of parameters, deck thickness or stud batch, and recorded on the stud weld log.
    StandardBS EN ISO 14555:2017 Annex A, Bend test. SCI P300.
    Common defectsBend test skipped at the start of a shiftFracture at the weld not identified and acted onTest not repeated after a parameter changeNo record of the test kept
  4. 10.
    Full 360° weld collar (ring) visually inspected on each stud
    What to look forWeld collar visible around the full circumference of the stud base, even fillet, no undercutting, porosity or excessive spatter. Studs with an incomplete collar identified and re-welded or replaced.
    Acceptable whenPer BS EN ISO 14555: full weld collar required around the stud, no more than minor gaps per the acceptance criteria in the standard. Any stud failing the visual check re-welded adjacent to the original position.
    StandardBS EN ISO 14555:2017. Manufacturer inspection criteria.
    Common defectsIncomplete collar not identifiedStud re-welded in exactly the same hole rather than adjacentPorosity or spatter masking a poor weldNo systematic visual check of every stud
  5. 11.
    Stud layout, spacing and total count match the composite design drawing
    What to look forStuds positioned at the centres and rows shown on the composite beam design drawing. Total count per beam matches the schedule, no studs omitted at beam ends or around penetrations.
    Acceptable whenStud position and count per the composite design drawing. Any deviation, for example a stud omitted due to an obstruction, referred to the design engineer before the pour, per BS EN 1994-1-1.
    StandardBS EN 1994-1-1:2004 (Eurocode 4). SCI P300. Composite design drawing.
    Common defectsStuds missed at beam endsFewer studs than the schedule requiresStuds welded through a deck lap rather than clear materialNo record of an approved deviation from the drawing

Questions people ask

What is a metal decking & shear studs QA inspection for?

To record that the work was checked against the specification before it was covered up or handed over: a pass or fail against each item, a measurement where one matters, and a photo where it failed. It is the evidence a client's quantity surveyor or clerk of works asks for, and the thing that settles the argument at final account.

What standards does this checklist check against?

Each item names its reference. On this checklist that includes BS EN 1090-4:2018, BS EN 1090-4:2018. SCI P300, BS EN 1090-4:2018. Manufacturer fixing schedule. SCI P300., SCI P300. Manufacturer installation guide., SCI P300. BS EN 1994-1-1 (Eurocode 4, BS EN ISO 14555:2017. The contract specification and the approved drawings always take precedence over a general standard; where they say something stricter, inspect to that.

Who signs a QA inspection off?

The person who carried out the check, named and dated, and where the contract calls for it the client's representative as a witness. The signature records that the check was done and what was found. It is not a warranty of the work.

How many items are on it, and do I have to use them all?

11 checks across 2 sections. Delete what does not apply to the job and add anything the specification asks for that is not here. A checklist that has plainly been thought about carries more weight than a long one nobody read.

Is this useful for a subcontractor as well as a main contractor?

More so. The subcontractor is the one who gets asked to come back and open something up. A signed inspection sheet with photos at the time is the cheapest insurance on a construction site.

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