Modular Bolt-On Balconies
QA inspection checklist

Offsite — Frame & Welds

1. 1.

   Frame material grade matches structural design
   What to look forSteel sections or aluminium extrusions stamped/marked with grade. Mill certs (EN 10204 3.1) or supplier delivery notes traceable to the cast/heat. Section sizes match the structural drawing. No mixed grades across the same load path.
   Acceptable whenSteel to BS EN 10025 — typically S275 or S355 per design. Aluminium to BS EN 755 — typically 6082-T6 for structural extrusions. EN 10204 3.1 certificates required for structural members. Designer to confirm grade interchange not permitted.
   StandardBS EN 1090-2:2018 (steel) / BS EN 1090-3:2019 (aluminium). BS EN 10025. BS EN 755. NSSS 7th Edition. SCI P427 — Modular construction guidance.
   Common defectsS275 substituted for S355 to save cost — capacity shortAluminium temper wrong (T4 vs T6) — strength deficitMill certificates cover wrong heat — not the steel deliveredCarbon steel cleats welded to aluminium frame — galvanic corrosion pathMixed grades across same load path — unpredictable failure mode
2. 2.

   Weld procedure record (WPS/WPQR) available and welder qualified
   What to look forWPS for each joint type signed off by a responsible welding coordinator (RWC). Welders hold current BS EN ISO 9606-1 (steel) or 9606-2 (aluminium) qualification covering the position and process used. Welder ID matches stamp on the finished joint.
   Acceptable whenFabricator must hold BS EN 1090-1 FPC certificate at execution class EXC2 minimum. WPS qualified to BS EN ISO 15614. Welder qualifications valid (renewed every 3 years or per work continuity rules). Responsible welding coordinator at IWE/IWT level for EXC2+.
   StandardBS EN 1090-1:2009+A1 — Conformity assessment. BS EN ISO 15614 — WPS qualification. BS EN ISO 9606-1/-2 — Welder qualification. BS EN ISO 14731 — Welding coordination.
   Common defectsNo WPS on the shop floor — welders working from memoryWelder qualification expired or wrong process (MIG vs TIG)No welder ID stamp on the joint — traceability goneEXC1 fabricator producing EXC2 work — no FPC for structuralAluminium welded by a steel-qualified welder — wrong process knowledge
3. 3.

   Welds visually compliant — no undercut, porosity, lack of fusion
   What to look forWelds smooth and consistent profile, no spatter on the visible face, no obvious undercut along the toe. Fillet legs match the WPS. Cap reinforcement on butt welds within tolerance — not piled or sunk. NDT records (MPI/PT/UT) on file for critical joints per design.
   Acceptable whenVisual acceptance to BS EN ISO 5817 quality level B (for EXC3) or C (for EXC2). Aluminium to BS EN ISO 10042. Undercut ≤ 0.5 mm. Fillet weld throat ±10% of design. NDT extent per BS EN 1090-2 Table 24 (typically 5% MPI on transverse fillets for EXC2).
   StandardBS EN ISO 5817 (steel) / BS EN ISO 10042 (aluminium) — Quality levels. BS EN 1090-2 Table 24 — NDT extent. BS EN ISO 17637 — Visual testing of welds.
   Common defectsUndercut at the weld toe — stress raiser, fatigue startPorosity visible on the surface — also present internallyLack of fusion at the root — load path discontinuousCap reinforcement piled too high — fatigue notchAluminium weld looks "dirty" — oxide not cleaned before welding
4. 4.

   Frame dimensions, diagonals and squareness within tolerance

   Record: Diagonal difference (mm)
   What to look forMeasured length, width and diagonals against the GA drawing. Diagonal difference indicates squareness. Frame sits flat on the jig with no rocking. No twist along the length (sighted from corner to corner).
   Acceptable whenLength tolerance ±3 mm up to 5 m, ±5 mm over 5 m per BS EN 1090-2. Diagonal difference ≤ 5 mm for nominal 2 m × 4 m module. Twist ≤ 1 mm per metre. Flatness within ±3 mm under self-weight.
   StandardBS EN 1090-2:2018 Section 11 — Geometrical tolerances. BS EN 1090-3 Annex for aluminium. NSSS cl.4.5.
   Common defectsDiagonal difference > 10 mm — frame is parallelogrammed, will not fit on siteTwist visible — module rocks on jig, will not sit flat on buildingLength short — gap at the building face after installDistortion from welding sequence — restraints not used during weld outHoles drilled before final weld-out — go out of position
5. 5.

   Building connection cleats positioned and drilled correctly
   What to look forCleats located at the correct height and centres for the supporting structure (steel beam, concrete edge slab, masonry padstone). Bolt hole pattern matches the design — diameter, pitch, edge distance. Cleat plate thickness as drawn. Slotted holes used where movement is allowed.
   Acceptable whenCleat position ±5 mm of GA. Hole pitch ±2 mm. Edge distance ≥ 1.2d for standard, ≥ 1.5d for slotted. Plate thickness ±0.5 mm. Slot length per design (not over-slotted to "make it fit").
   StandardBS EN 1090-2 cl.6.6 — Holes. SCI P358 — Joints in steel construction: simple joints. SCI P398 — Moment connections.
   Common defectsCleats positioned by tape from frame end — accumulated errorSlotted holes opened up further on site to make it fit — connection capacity compromisedEdge distance < 1.2d — bolt tears through plate edge under loadCleat plate thickness reduced — engineer not consultedNo slot where thermal movement is required — connection cracks first winter
6. 6.

   Powder coat / paint finish to specification

   Record: DFT (μm)
   What to look forCoating even across all surfaces, no runs, sags or orange peel. Coating reaches into corners and bolt-holes (or holes are touched up). DFT readings consistent. Edges (typical failure point) at full thickness. Pre-treatment (chromate/chrome-free for ali, blast/etch prime for steel) per spec.
   Acceptable whenTotal DFT 60-120 μm for architectural powder coat (typical QUALICOAT class). Edge DFT ≥ 90% of nominal. Adhesion to BS EN ISO 2409 cross-hatch class 0-1. Pre-treatment per BS EN 12206-1 (aluminium) or BS EN ISO 12944 (steel). Marine/coastal: seaside grade powder coat or 2-coat system.
   StandardBS EN 12206-1 — Coating of aluminium. BS EN ISO 12944-5 — Steel paint systems. QUALICOAT specification (architectural ali). QUALANOD (anodised). BS EN ISO 2360 — DFT measurement.
   Common defectsDFT thin at edges — coating fails first at the most exposed lineOrange peel or pinholes — application or cure temperature wrongAdhesion failure — pre-treatment skipped or contaminated substrateStandard polyester used in coastal zone — chalks and fades within 5 yearsTouch-up paint mismatched — visible patches across the run

Offsite — Aluminium Cladding (Soffits, Fascias, Sides)

1. 7.

   Aluminium grade and thickness match specification
   What to look forSheet/extrusion stamped with EN designation. Thickness gauged at multiple points — not just the visible edge. Soffit panels typically 2-3 mm, fascia panels 2-4 mm. Tray panels formed with sharp corners and no cracking at the bend.
   Acceptable whenSheet alloy typically 5005 (H22/H24 temper) or 3003 for formed panels. Extrusions 6063-T6. Thickness tolerance per BS EN 485-4 (sheet) — typically ±10%. Tray edge folds without cracking at the bend radius (2T minimum).
   StandardBS EN 485-1 to 4 — Aluminium sheet and strip. BS EN 755-1 to 9 — Extruded rod, bar and profiles. BS EN 12206-1 — Coating.
   Common defectsSheet under-gauge — supplier substituted thinner stockCracking at tray fold — wrong alloy or temper for formingMixed alloys across visually identical panels — different weathering responseExtrusion temper wrong — soft, deflects in service
2. 8.

   Fixings stainless steel — no carbon steel into aluminium
   What to look forScrews, rivets, bolts visibly stainless. Heads not painted-over carbon steel. Where carbon steel is unavoidable (e.g. into the main steel frame), isolation washers/sleeves are fitted to break the galvanic couple. No black ferrous swarf inside the panels.
   Acceptable whenFixings to A2 (1.4301) minimum for inland, A4 (1.4401) for coastal/marine per BS EN ISO 3506. Carbon steel only with full galvanic isolation. Rivet mandrel material matches body. Fixing centres per cladding designer (typically 250-400 mm on edges, 400-600 mm in field).
   StandardBS EN ISO 3506 — Stainless steel fasteners. BS EN ISO 14713-1 — Corrosion protection. CWCT TN66 — Bimetallic corrosion in metal panels.
   Common defectsCarbon steel screws into aluminium soffit — orange streaks within 12 monthsA2 stainless used in coastal zone — pitting and tea-stainingRivet body stainless but mandrel mild steel — bleeds rust from the centreFixing centres opened up to save fixings — panels rattle in wind
3. 9.

   Panel alignment, joint width and edge straightness

   Record: Joint width (mm)
   What to look forPanel edges line up across the run — sighted along the length. Joint widths consistent. Reveals at corners square. Cassettes pulled into clips fully — no panels sitting proud. Visual face free of "oil canning" (centre dishing).
   Acceptable whenJoint width ±1 mm of nominal across a 6 m run. Edge alignment ±2 mm. Reveal squareness ±1 mm. Oil canning acceptable only where designer has reviewed against MCRMA panel flatness criteria (typically T or U for premium facades).
   StandardCWCT Standard for Systemised Building Envelopes Section 8. MCRMA Technical Paper 18 — Conventions for assessing flatness. BS 8298 — Code of practice for cladding.
   Common defectsStepped joints — clips not pulled or panel tabs offJoint width varies 4-12 mm — setting-out drift across the runOil canning visible across the soffit — sheet too thin or fixing pattern wrongCorner reveals out of square — short of trim or wrong mitre
4. 10.

   No transit damage on visible faces
   What to look forVisible faces inspected under raking light. Scratches, dents, gouges, witness marks from packaging. Protective film/peel-off coat still in place where retained. Edges (most vulnerable to chip) intact.
   Acceptable whenNo scratches > 25 mm visible at 2 m viewing distance per CWCT Section 8.4. No dents deeper than 0.5 mm. Touch-up acceptable only by manufacturer-supplied repair pen — paint matching from a tin is rejected on architectural finishes.
   StandardCWCT Standard Section 8.4 — Visual acceptance. Manufacturer surface defect classifications.
   Common defectsForklift gouge on the edge from yard handlingChain marks across the face — module lifted without spreader barStrap witness on powder coat — straps not protectedTouch-up by tinned paint — colour and gloss mismatch obvious on the buildingScratches from stacking without interleaving
5. 11.

   Colour match across all panels — same batch / RAL
   What to look forPanels viewed together under daylight or daylight-balanced lamps. RAL number and powder batch number stamped on the back of each panel — all match. No "shaded" run between two batches across a single elevation.
   Acceptable whenSingle batch for any one elevation where possible. Where multi-batch unavoidable, ΔE ≤ 1.0 between batches measured at 60° gloss per QUALICOAT class 1 architectural. Powder supplier batch numbers recorded in the project pack.
   StandardQUALICOAT specification class 1 (architectural). BS EN ISO 11664 — Colour metrology. RAL Design System.
   Common defectsTop row panels visibly different shade — second batch run halfway throughPowder coater used a substitute supplier — same RAL number, different chemistryNo batch traceability — colour issue cannot be resolved without recoating everythingTouch-up paint different gloss to powder coat — patchy under raking light
6. 12.

   Bird / vermin mesh fitted to soffit perforations or vents
   What to look forStainless steel mesh fitted behind any perforated panel, drip slot or open vent in the soffit. Mesh aperture small enough to exclude insects where required. Mesh secured properly — no gaps at edges.
   Acceptable whenMesh aperture ≤ 10 mm for birds (NHBC), ≤ 4 mm for rodent exclusion, ≤ 1.5 mm where insect exclusion required. Material stainless A2 minimum. Continuous behind the perforated zone with no unmeshed gaps at edges or fixings.
   StandardNHBC Standards Chapter 7.2 — Pitched roofs and soffits. BS EN 13501-1 — Mesh must not compromise fire performance.
   Common defectsNo mesh fitted — birds nest in the soffit void within monthsPlastic mesh used — fails fire reaction class requirementGaps at the mesh edge — pest entry routeMesh fixed only at top — sags away from the panel underside

Offsite — Balustrade & Infill

1. 13.

   Top rail / handrail height correct for occupancy

   Record: Height (mm)
   What to look forHeight measured from finished floor (decking) to top of rail. Consistent across the full run. Continuous at corners — no drops at returns. Profile graspable per Approved Document M for accessibility where required.
   Acceptable when1100 mm minimum on balconies above 600 mm fall height per Approved Document K1. Domestic balcony alternative 900 mm at stair pitch line. 1100 mm for non-domestic. Handrail grip profile per Approved Document M cl.1.36 where M is in scope.
   StandardApproved Document K (England) — Protection from falling. Approved Document M — Access. BS 6180:2011 — Barriers in and about buildings. BS 8579:2020 — Design of balconies and terraces.
   Common defectsTop rail set to 1000 mm — fails Approved Document K on a non-domestic balconyDrop at corner where two runs meet — continuity lostHandrail profile not graspable — fails accessibilityDecking thicker than allowed for in the fabrication — effective height short of 1100 mm after install
2. 14.

   Infill spacing — no 100mm sphere passes

   Record: Max gap (mm)
   What to look forGap between vertical bars, between bottom rail and decking, between glass panels and surrounding frame — all checked with a 100 mm sphere gauge (or 99 mm test bar). No combination of rails creates a foothold step at child-reachable height.
   Acceptable whenNo 100 mm sphere shall pass any gap in a barrier protecting children per Approved Document K cl.3.2 and BS 6180 cl.6.2.1. Bottom rail to decking ≤ 100 mm. No horizontal rails or features between 150-760 mm that could be climbed.
   StandardApproved Document K cl.3.2 — Protection from falling. BS 6180:2011 cl.6.2 — Construction. BS 8579:2020.
   Common defectsBottom rail set 110 mm above decking — sphere passesHorizontal mid-rail at child-climb height — creates a ladderGlass panel installed with > 100 mm gap at top — sphere passes over the panelMesh aperture > 100 mm at the diagonal
3. 15.

   Balustrade load tested or design-verified
   What to look forTest certificate or structural calculation pack covering the balustrade for the relevant occupancy load. Connection of balustrade to deck/frame designed and fabricated to match the tested arrangement. No on-site improvisation away from the design.
   Acceptable whenDesign horizontal line load per BS 6399-1 / BS EN 1991-1-1 Table NA.8: 0.74 kN/m (domestic/balcony category A), 1.5 kN/m (assembly/category C), 3.0 kN/m (category C5/grandstand). Infill load 0.5-1.5 kN/m² depending on category. Test or calc by chartered engineer.
   StandardBS EN 1991-1-1 Table NA.8 — Imposed loads. BS 6180:2011 cl.7 — Strength and stability. BS 8579:2020. Building Safety Act 2022.
   Common defectsNo calc pack on file — design intent not documentedGlass panel clamps spaced wider than tested arrangement — capacity reducedTest arrangement used a different post centre to the production unitConnection to the deck not assessed — balustrade tested, fixing not
4. 16.

   Glass infill specification and lamination correct
   What to look forGlass etching/stamp visible on the edge — type, thickness, manufacturer. Laminated build with PVB or SGP interlayer per spec. Edge condition (polished or seamed) per design. No edge chips that could propagate. Toughened glass heat-soak tested where specified to mitigate nickel sulphide failure.
   Acceptable whenLaminated to BS EN ISO 12543. Toughened to BS EN 12150. Heat-soak test to BS EN 14179 where used as overhead or to mitigate spontaneous failure. Pendulum impact class to BS EN 12600 — typically class 1(B)1 for balustrade infill. Interlayer thickness ≥ 1.52 mm PVB or 1.52 mm SGP per design.
   StandardBS EN ISO 12543 — Laminated glass. BS EN 12150 — Toughened glass. BS EN 14179 — Heat-soaked toughened. BS EN 12600 — Pendulum impact. BS 6180 cl.6.5. BS 8579.
   Common defectsSingle-pane toughened used in a balustrade — fails on retain-the-load criterion if it breaksPVB used where SGP specified — different post-breakage capacityNo heat-soak — nickel sulphide failures over timeEdge chip from poor handling — propagation pointInterlayer thickness reduced to save cost — no longer meets impact class
5. 17.

   Gate / leaf opening (if fitted) — latch and self-close operate
   What to look forGate self-closes from any open position. Latch engages without forcing. Catch holds against typical wind load. Gate fully matches the balustrade in height and infill spacing — no shortcuts at the swing edge. Pinch points designed out.
   Acceptable whenSelf-closing from 90° open per BS 6180 and Building Regs where the gate protects a fall hazard. Latch action one-handed. Gate gap from latch post ≤ 100 mm sphere when closed. Closer adjustable for wind exposure.
   StandardBS 6180:2011 cl.10 — Doors and gates. Approved Document K. Approved Document M (accessibility).
   Common defectsGate hangs open — closer not adjusted or removed altogetherLatch sticks — needs two hands or a lift to operateGap at swing edge > 100 mm — sphere passesPinch point at the hinge — finger trap

Offsite — Decking & Fire Performance

1. 18.

   Decking fire reaction class A1 or A2-s1,d0
   What to look forDecking plank stamped with manufacturer, batch and fire classification. Classification certificate (BS EN 13501-1) for the exact product code on the project pack. Where building height > 11 m or relevant building scope under BSA 2022, A2-s1,d0 minimum is mandatory.
   Acceptable whenBS EN 13501-1 classification A1 (non-combustible, no test required for some materials) or A2-s1,d0 (limited combustibility). Mandatory A2-s1,d0 or better on external walls of relevant buildings ≥ 11 m under Building Regulations Schedule 1 Reg 7(2). Manufacturer certificate cross-referenced to product code on the delivery note.
   StandardBS EN 13501-1:2018+A1:2019 — Fire classification. Building Regulations Approved Document B Volume 2. Building Safety Act 2022. Building (Amendment) Regulations 2018 (Reg 7).
   Common defectsClass B or C decking installed on a relevant building — non-compliant under Reg 7"Fire retardant" timber claimed — but BS EN 13501-1 cert is for a different product codeCertificate covers a different colour/finish — class not transferableDecking specified by trade name only — no traceable fire classSubstituted on site without checking — buyer assumed equivalence
2. 19.

   Decking secured per fixing schedule, no movement under load
   What to look forWalked the full deck — no rock, no rattle, no creak. Fixings at every joist per the fixing schedule. Concealed clip systems engaged fully. Stainless screws (not bright zinc) used for the marine environment.
   Acceptable whenFixings per manufacturer schedule — typically every joist intersection. Clip torque per manufacturer (often 1-2 Nm). No deflection > L/300 under a 1.5 kN/m² imposed load (typical category A balcony). Fixings A2 stainless minimum, A4 for coastal.
   StandardBS EN 1991-1-1 Table NA.7 — Balcony imposed loads. BS 8579:2020 Section 8. Manufacturer technical literature.
   Common defectsConcealed clips not fully engaged — board lifts under footScrews missed every other joist — board flex audibleBright zinc screws used outdoors — rust streaks within 12 monthsBoards installed wrong way up — drainage channels blockedNo expansion gap at ends — boards buckle in summer heat
3. 20.

   Drainage gaps between boards clear and consistent

   Record: Gap (mm)
   What to look forGap between deck boards consistent along the run. Gaps clear of swarf, debris or sealant overspill that would block drainage. Fall to the drainage line visible — water sheets toward outlet not toward the building face.
   Acceptable whenBoard-to-board gap per manufacturer — typically 4-6 mm. Variation ±1 mm. Gap clear, no blockages. Surface fall to drainage 1:60 minimum (BS 8579) to avoid ponding.
   StandardBS 8579:2020 cl.7.4 — Drainage and falls. Manufacturer installation guide.
   Common defectsGaps blocked with sawdust/swarf — water sits on deckReverse fall — water tracks to the building faceVariable gap — wedges visible across the runNo gap at all — boards laid tight, no drainage
4. 21.

   Slip resistance (PTV) recorded — wet and dry

   Record: PTV (wet)
   What to look forSlip test certificate (pendulum test BS 7976) or manufacturer test data for the exact deck product. Wet PTV is the critical figure for external balconies. Surface texture intact — not polished away or filled with sealant.
   Acceptable whenPendulum Test Value (PTV) ≥ 36 in the wet condition for low slip risk per HSE/UKSRG guidance. PTV 25-35 is moderate, < 25 is high slip risk. Test by accredited lab to BS 7976-2.
   StandardBS 7976-2:2002+A1:2013 — Pendulum testers. UKSRG Guidelines on slip resistance. HSG155 — Slips and trips.
   Common defectsPTV not measured — risk unquantifiedPTV 20 in the wet — claims management problem waiting to happenSurface "smoothed" by powder coat overspray — slip resistance goneTest data covers the dry product only — wet figure missing
5. 22.

   Underside / soffit fire barrier as required
   What to look forWhere the balcony is part of an external wall on a relevant building, the underside cavity is either non-combustible or fitted with cavity barriers at floor levels per Approved Document B. Membrane (if used) class A1 or A2-s1,d0. No combustible insulation in the void.
   Acceptable whenOn relevant buildings ≥ 11 m (England), materials in the external wall must achieve A2-s1,d0 or better per Reg 7(2). Cavity barriers at every floor level per AD B Vol 2 cl.9.7. Specialist designer sign-off on the cavity strategy.
   StandardApproved Document B Volume 2 (2019, amended) — Fire safety. Building (Amendment) Regulations 2018, Reg 7. Building Safety Act 2022. PAS 9980 — Fire risk appraisal.
   Common defectsCombustible XPS or PIR placed in the balcony soffit cavity — non-compliant on relevant buildingsNo cavity barrier at floor levels — fire can track the full heightPE-cored ACM soffit panel — total ban under Reg 7"Limited combustibility" misread as A2 — different classification

Offsite — Drainage

1. 23.

   Outlet sized for floor area and rainfall intensity
   What to look forDrainage calc on file or noted on the design — outlet diameter selected for the balcony plan area and the design rainfall intensity (BS EN 12056). Outlet integrated into the deck construction so it cannot be lifted away.
   Acceptable whenDesign rainfall typically 0.014 L/s/m² for a 5-minute storm in most of UK (BS EN 12056-3 Table 2 for England/Wales). Outlet capacity ≥ design flow with a leaf-guard reduction factor of 0.5. Typical 75 mm outlet for ≤ 10 m² balcony, 100 mm above.
   StandardBS EN 12056-3:2000 — Roof drainage. BS 8579:2020 cl.7. BS 6367 (older reference still seen).
   Common defectsOutlet sized by guesswork — under-capacity, overflows in heavy rainLeaf guard not factored — calc looks fine, real-world capacity halvedOutlet sat above the deck membrane — water ponds before reaching itNo overflow provision — sustained downpour floods the deck
2. 24.

   Drainage routed away from building face
   What to look forOutlet pipe routed to a rainwater downpipe, hopper or other engineered discharge — not free-falling onto the building face below. Connection to the building rainwater system tied in by the install team. No drips landing on lower balconies, glazing or footways.
   Acceptable whenNo free discharge onto the building face per BS 8579 cl.7.5. Connection to a hopper or downpipe with secured joint. No drips onto pedestrian areas or other façade elements. Pipe material UV-stable for external use.
   StandardBS 8579:2020 cl.7.5 — Drainage discharge. BS EN 12056-3 — Roof drainage. NHBC Standards 7.2.
   Common defectsDrain free-falls onto building face — stains, damp, freeze damagePipe connected to a planted area — overflows and erodesPVC-U pipe used externally without UV stabiliser — becomes brittle in 5 yearsDrip onto a lower balcony — nuisance and slip risk
3. 25.

   Fall to outlet — no ponding

   Record: Fall (1:n)
   What to look forSpirit level laid across the deck toward the outlet shows positive fall. After a flood test (or 5-litre bucket pour), water drains within seconds — no pools left at the corners or behind the balustrade.
   Acceptable whenMinimum fall 1:60 per BS 8579 cl.7.4. No standing water 5 minutes after flow stops. Falls maintained in all four directions where outlet is central.
   StandardBS 8579:2020 cl.7.4 — Falls and drainage. BS 6229:2018 (flat roofs — reference).
   Common defectsFlat deck or reverse fall — water sits in cornersFall lost behind balustrade upstand — water stagnant at the rail1:80 used "because it looks OK" — falls outside the standardFall to wrong side — water heads to the building rather than the outlet
4. 26.

   Drip edge prevents water tracking onto building face
   What to look forDrip detail at the balcony outer edge — formed groove, drip bead or projecting trim that breaks surface tension and forces water to fall away from the building. Drip continuous along the full length, including at end returns.
   Acceptable whenDrip projection ≥ 25 mm from the wall face per NHBC. Drip groove min 5 mm deep × 5 mm wide. Continuous — no interruption at junctions or under balustrade posts.
   StandardNHBC Standards Chapter 6.9 — Cills and copings. BS 8579 cl.6 — Detailing.
   Common defectsNo drip — water tracks back across the soffit and stains the buildingDrip groove blocked with sealant — bridged surface tension, water tracks backDrip interrupted at posts — local staining at every postDrip projection only 10 mm — wind blows water back onto wall in storms

Offsite — Lifting, Marking & Documentation

1. 27.

   Lifting points designed, marked SWL, and certified
   What to look forLifting eyes / shackle points clearly marked SWL on the module. Lifting points designed and tested by a competent engineer — design calc and test certificate on file. Bolted-on lifting eyes have the correct thread engagement and torque.
   Acceptable whenSWL mark visible and durable per LOLER. Lifting points designed for the load + appropriate factor (typically 4:1 for chain/sling attachments). Test certificate dated within 12 months for re-usable lifting eyes per LOLER thorough exam.
   StandardLOLER 1998 — Lifting Operations and Lifting Equipment Regulations. BS EN 13155 — Non-fixed load lifting attachments. CDM 2015 Reg 8 (design risk).
   Common defectsNo SWL mark — operator does not know the limitLifting eye welded on without engineer involvement — fails in serviceLifting eye undersized — bent or torn during the liftNo thorough examination cert for re-usable points — LOLER non-compliantSling angle exceeds design — point overloaded
2. 28.

   Lifting plan / method statement provided
   What to look forDocumented lifting plan covering rigging arrangement, sling lengths, spreader beam (if used), maximum wind speed for the lift, exclusion zone, signaller and slinger qualifications. Plan signed by an appointed person (AP).
   Acceptable whenLifting plan per BS 7121 prepared and signed by appointed person. Wind cut-off typically 10-12 m/s for a high-windage panel. Spreader beam used to keep sling angle within design. Crane capacity > module weight + rigging × duty factor.
   StandardBS 7121-1 to 4 — Code of practice for safe use of cranes. LOLER 1998. CDM 2015 (Principal Contractor responsibility on site).
   Common defectsNo lifting plan — slinger improvising riggingWind cut-off not stated — lift proceeds in unsafe windNo appointed person sign-off — chain of competence brokenSpreader beam needed but not used — sling angle exceeds eye capacity
3. 29.

   ID plate fitted — manufacturer, serial, design load, year
   What to look forPermanent ID plate (stainless or anodised aluminium, riveted) fitted in a location that remains visible after install — typically the underside near the building face. Carries manufacturer, serial number, design load category, mass, year of manufacture and the BS/EN reference.
   Acceptable whenPer BS 8579:2020 cl.10 and CPR-aligned Declaration of Performance: manufacturer, model, batch/serial, design imposed load, mass, year of manufacture, harmonised standard reference where applicable.
   StandardBS 8579:2020 cl.10 — Marking. UK Construction Products Regulation (post-Brexit CPR). Building Safety Act 2022 — Golden thread.
   Common defectsNo ID plate — module is anonymous in service, no traceabilityID plate fitted but in a location that gets concealed by claddingPlastic label used — degrades in UV, unreadable within 2 yearsSerial missing — module cannot be traced back to its production records
4. 30.

   Mass verified and marked on the module

   Record: Mass (kg)
   What to look forModule weighed at the factory — weigh-bridge ticket or calibrated load cell record on file. Mass marked on the module in a location visible to the crane operator. Compared to design weight — discrepancies > 5% investigated.
   Acceptable whenMass marked per BS 7121-3 to inform crane selection. Tolerance ±5% of design mass. Heavier than design = investigate (extra weld, wrong material). Lighter = investigate (missing items).
   StandardBS 7121-3:2017 — Safe use of cranes — Mobile cranes. LOLER 1998. BS 8579 cl.10.
   Common defectsMass estimated, not measured — crane underspec for actual weightMass mark missing — crane operator works from drawings (which may be wrong)Heavier than design — investigation skipped, root cause unknownWeighbridge ticket lost — traceability gone for the project file
5. 31.

   Declaration of Performance and O&M pack ready
   What to look forDeclaration of Performance (DoP) per UK CPR for the structural balcony as a kit/assembly. O&M pack including maintenance schedule (powder coat washdown frequency, drainage clearance, bolt re-torque interval, glass cleaning), spares list, fire performance certificates, design calc summary. Building Safety Act golden thread items captured.
   Acceptable whenDoP per UK CPR for the assembly where covered by a harmonised standard. O&M per CDM 2015 Reg 12(7) Health and Safety File. BSA 2022 golden thread for relevant buildings — digital, accurate, accessible.
   StandardUK Construction Products Regulation. CDM 2015 Reg 12(7). Building Safety Act 2022 cl.62-65. BS 8579 cl.11 — Information for the building user.
   Common defectsNo DoP — product not legally placed on the marketO&M empty — homeowner has no idea how to maintain the unitFire performance certs missing from the pack — gap in the golden threadMaintenance interval absent — drainage blocks, deck stains, no schedule to prompt cleaning

On-Site — Connection to Building

1. 32.

   Bolt grade, count and pattern match design
   What to look forBolts visually match design — grade marked on the head (8.8, 10.9, A4-80). Number of bolts per cleat matches drawing. Pattern (e.g. 4-off M16 at 100×100 mm centres) checked against the GA. No "we ran out of M16, used M12" improvisation.
   Acceptable whenBolt grade per design — typically 8.8 for general structural or 10.9 for preloaded. Stainless A4-80 for marine. Bolt count and pattern as drawn — no substitutions without an RFI and engineer sign-off. Edge distance ≥ 1.2d per BS EN 1090-2.
   StandardBS EN ISO 4014 — Hexagon head bolts. BS EN 14399 — High-strength preloaded. BS EN ISO 3506 — Stainless. BS EN 1090-2 cl.8.
   Common defectsWrong grade bolt used — 8.8 substituted for 10.9 in a preloaded jointTwo bolts short in the pattern — capacity reducedMild steel bolt into stainless cleat — galvanic corrosion pathBolt longer than required — protrusion bottoms out before clampingBolts not full-thread engaged — nut not advanced to the back face
2. 33.

   Bolts torqued to design and torque-marked

   Record: Torque (Nm)
   What to look forMarker paint stripe across nut, bolt and connected plate. Stripe continuous indicates no movement since torque-up. Torque wrench calibration certificate on file (within 12 months). Torque sequence followed for multi-bolt connections — diagonal, then full pattern.
   Acceptable whenTorque per design — for 8.8 M16 typically 200-220 Nm dry, lower if lubricated. Preloaded connections (HSFG) to BS EN 1090-2 cl.8.5 by torque method or combined method. Torque wrench calibration current. All bolts torque-marked.
   StandardBS EN 1090-2:2018 cl.8 — Mechanical fastening. BS EN 14399-9 — HRC tension control bolts. NSSS Section 8.
   Common defectsBolts "feel tight" — actual torque unknown, no wrench usedCalibration certificate expired — torque values suspectNo torque marks — cannot verify maintained tension over timeTorque applied in random sequence — uneven clamping, slip in serviceLubricated bolts torqued to dry value — over-tensioned, risk of fracture
3. 34.

   Resin anchors (if used) — cure observed and pull-test record
   What to look forResin anchor manufacturer + product code on the cartridge. Hole drilled, blown and brushed per the manufacturer's ETA (European Technical Assessment). Cure time logged before any load applied (typically 30 min @ 20°C, longer in cold). Pull-test certificate by an accredited tester on at least the sample rate stated by the engineer.
   Acceptable whenAnchors per a current ETA / UKTA assessment. Installation by trained operative (manufacturer certification). Cure time per manufacturer datasheet at site temperature. Proof-load test typically 1.5 × working load on a stated sample rate (often 10% of fixings, minimum 3 per joint type).
   StandardEN 1992-4 / Eurocode 2 Part 4 — Design of fastenings. Manufacturer ETA (e.g. Hilti ETA-07/0260, Fischer ETA-12/0258). CFA Guidance Note on Post-Installed Anchors.
   Common defectsHole not brushed — bond capacity less than half of catalogue figureCure time short-circuited because the next task was waitingNo pull-test record — installer competence and bond unverifiedWrong resin used — winter grade in summer or vice versaCartridge mixer nozzle not changed between holes — partial cure on first 200 mm
4. 35.

   Module plumb, level and aligned with neighbours

   Record: Deviation (mm)
   What to look forSpirit level along the front edge, plumb on the building-face uprights. Decking level checked across the diagonals. Aligned with the module above/below — visual sight line along the elevation. Gap to neighbour modules consistent.
   Acceptable whenVerticality ≤ h/500 per BS EN 1090-2 D.2.20. Level deviation ≤ 5 mm across module front-to-back. Alignment with adjacent module ±3 mm — visible to the eye if worse. Gap to neighbour ±2 mm of design.
   StandardBS EN 1090-2:2018 Annex D. BS 8579 cl.9 — Installation tolerance.
   Common defectsModule leans forward — cantilever has dropped under self-weight, anchors not preloadedStair-step alignment between floors — building face deviation not accounted forVariable gap to neighbour — visually obvious "drift" along the elevationLevel lost across diagonal — module twisted during install, packing wrong
5. 36.

   Cantilever deflection within design under live load

   Record: Deflection (mm)
   What to look forLoaded test (sandbag, water containers or assembled occupancy) at the free end measures the deflection. Reading against the design deflection limit. Module returns to original level when load is removed — no permanent set.
   Acceptable whenLive load deflection ≤ L/180 (typical balcony cantilever) or ≤ L/250 where finishes are sensitive, per BS EN 1990 Table A1.4. No permanent set on removal. Sentinel modules tested per project QA plan.
   StandardBS EN 1990:2002+A1:2005 Annex A1 — Serviceability. BS EN 1991-1-1 — Imposed loads. BS 8579 cl.5 — Structural design.
   Common defectsPermanent set after load test — connection slipping or yieldingDeflection exceeds L/180 — module under-designed or connection too flexibleNo load test performed — capacity unverifiedSandbag load not representative — area or pattern wrong

On-Site — Building Interface & Sealing

1. 37.

   Sealant joint to building face — primer used, no gaps
   What to look forSealant continuous around the perimeter where the module meets the building. Primer applied per the sealant manufacturer's data sheet — primer flash time observed. Backing rod used in the right depth. Tooled finish concave, no air bubbles, no skip at the corners.
   Acceptable whenSealant per ISO 11600 class — F-25 LM (low modulus) for high-movement joints typical. Joint width to depth ratio ≈ 2:1 with backing rod. Primer per manufacturer datasheet. Movement capability ≥ design joint movement.
   StandardISO 11600:2002+A1:2011 — Sealant classification. ASTM C920 (reference). BS 6093:2006 — Joint design. CWCT Standard Section 8.7.
   Common defectsNo primer used — sealant peels off the building face within a yearBacking rod missing — sealant pulled into the joint deeply, low movement capacitySealant overspilled and smeared — visible mess on the claddingThree-sided adhesion (sealant bonded to backing rod) — restrained, tears under movementSkip at the corner — water entry path right at the structural connection
2. 38.

   Flashings / drip details fitted above and below
   What to look forFlashing above the module sheds water clear of the joint. Lower flashing/drip prevents water tracking back under the module to the building face. Flashings lapped correctly with cladding/render above. Mechanically fixed and sealed at terminations.
   Acceptable whenLap direction follows the water — top flashing over building face, dropping over the module top edge by ≥ 50 mm. Drip projection ≥ 25 mm. Stainless or aluminium flashing — never galvanised steel against an aluminium balcony.
   StandardNHBC Standards 6.9. BS 8579 cl.6. LRWA / SPRA roofing guidance (analogous detailing).
   Common defectsNo top flashing — water dribbles into the joint and the buildingDrip flashing reverse-lapped — water tracks under the moduleGalvanised steel flashing on an aluminium module — galvanic corrosionFlashing not sealed at terminations — wind-driven rain enters
3. 39.

   Fire cavity barrier integrity maintained where the module penetrates external wall
   What to look forWhere the connection bolts or cleats pass through an external wall containing a cavity, the cavity barrier (intumescent strip, mineral wool sock or open-state vent barrier) is sealed around the penetration. No "convenient holes" left in fire-stopping. Specialist firestopper has installed and signed off.
   Acceptable whenCavity barrier continuity per Approved Document B Vol 2 cl.9.7. Penetration sealed with a firestopping system tested in the relevant configuration to BS EN 1366-4. Installed by a competent firestopper (FIRAS / IFC SK4 / equivalent). Record on the BSA golden thread for relevant buildings.
   StandardApproved Document B Vol 2. BS EN 1366-4 — Linear joints. BS 8214 — Fire doors / openings (related). PAS 9980. ASFP technical guidance.
   Common defectsPenetration left unsealed — fire compartmentation breachedWrong sealant used (gunned silicone instead of intumescent) — fails in fireFirestopper not certified — installation not traceablePhoto record missing — BSA golden thread gapMineral wool packed but not faced with sealant — smoke leakage
4. 40.

   Thermal break / cold-bridging detail intact
   What to look forConnection includes the designed thermal break (e.g. structural thermal-break plate, isolated bolted clip with low-conductivity bearing). No metal-to-metal direct line from the cantilever beam through to the internal slab edge bypassing the break.
   Acceptable whenDetail matches PSI-value (linear thermal transmittance) calc on the project pack. Thermal break manufacturer's installation sequence followed. No metal bypass routes installed for "ease".
   StandardApproved Document L — Conservation of fuel and power. BR 497 — Conventions for calculating linear thermal transmittance. Manufacturer ETA for thermal break products (e.g. Schöck Isokorb).
   Common defectsThermal break omitted — internal condensation forms on the slab edge in winterBolt installed through the break that bypasses the insulator — point thermal bridgeWrong product variant — load-rated version replaced with light-dutyInstallation sequence skipped — break compressed or misaligned
5. 41.

   Cable and drainage penetrations through the module are sealed
   What to look forLighting or socket cables routed through the module are sleeved and sealed at the penetration. Drainage outlet pipe connection to the building rainwater system has a watertight collar or factory swept-tail fitting. No open holes left in soffit panels or fascia where cables emerge.
   Acceptable whenCable penetrations sealed against water ingress and fire spread (if rated). Drainage joints solvent-welded or push-fit with seal per manufacturer. No exposed cable insulation. All openings closed off to UV and pest entry.
   StandardBS 7671 — Electrical installation (cable supports). BS EN 12056-3 — Drainage. BS 8579 cl.7.
   Common defectsDrainage joint loose — leak under loadCable hole oversized and unsealed — wasps and wind-driven water inCable insulation chafed at the panel edge — fault waitingOpen hole left in the soffit for "future use" — never closed off

On-Site — Post-Install Verification

1. 42.

   No transit or install damage to aluminium finish
   What to look forModule inspected on completion under raking light. Any scratches, dents or chips from lifting straps, slinging or close-quarters work documented and repaired by manufacturer touch-up only. Final clean removes installer fingerprints, sealant smear and adhesive residue.
   Acceptable whenNo defects > CWCT Section 8.4 viewing distance criteria (no scratches > 25 mm visible at 2 m). Touch-up to match factory finish — manufacturer-supplied pen or repair kit. Final clean to manufacturer-recommended cleaner only — no abrasive pads.
   StandardCWCT Standard Section 8.4. QUALICOAT (post-installation). Manufacturer cleaning and maintenance guide.
   Common defectsSling marks across the fascia — module slung without protectionSealant smear on the cladding face — never wiped before cureTouch-up paint from a tin — colour and gloss off by a noticeable amountScratch from a ladder rested against the balustrade postAbrasive cleaner used in handover clean — micro-scratching the powder coat
2. 43.

   Flood test — drainage runs clear in 1 minute
   What to look forBucket of water (10-20 L) poured at the deck high point. Water sheets to outlet within seconds, leaves the outlet within 1 minute, exits the building rainwater system without backup. No leaks into the soffit void or down the building face.
   Acceptable whenPer BS 8579 cl.7 — drainage demonstrably operates. Flow leaves the module via the intended outlet within 1 minute of test pour. No drips, leaks, or unintended discharge paths. Test witnessed and recorded.
   StandardBS 8579:2020 cl.7. BS EN 12056-3 — Roof drainage.
   Common defectsPour test never done — drain blockage discovered by the first homeownerSlow drainage — outlet undersized or partially blocked with swarfLeak into the soffit void — joint or membrane failure not picked up offsiteWater tracks to the building face — falls were wrong
3. 44.

   Balustrade integrity — push test, no movement at connections
   What to look forDesignated test load (or representative push from competent inspector) applied at the top rail. Posts do not pivot at the deck. Glass clamps do not slip. Handrail does not flex visibly between posts. All fixings tight on follow-up check.
   Acceptable whenNo measurable permanent deflection at handrail after design test load (0.74 kN/m or higher per category). Fixings remain torqued. Glass clamps grip without slip per manufacturer datasheet.
   StandardBS 6180:2011 cl.7. BS EN 1991-1-1 Table NA.8. BS 8579.
   Common defectsPost pivots at the deck — base plate fixing too shortGlass slips in the clamp — wrong rubber inserts or under-torquedHandrail flexes audibly between posts — post spacing too wide for sectionPermanent set in the rail after a push — yield in the connection
4. 45.

   Walk-on test — decking firm, no rocking, no rattle
   What to look forFull deck walked corner to corner, including standing on each board. No movement felt or heard. Clips engaged. Edge boards (often the first to lift) firm. Underfoot consistent, no soft spots.
   Acceptable whenNo audible rattle or felt movement under a single person's weight. Deflection ≤ L/360 under foot traffic (BS EN 1990 vibration-sensitive). All clips engaged.
   StandardBS EN 1990 Annex A1 — Serviceability. BS 8579 cl.8. Manufacturer installation guide.
   Common defectsEdge board lifts when stood on — clip missed at the endSoft spot in the middle of a span — joist spacing exceeds manufacturer maxRattle from a loose fixing — picked up by the first occupant, not on handoverDecking lifts at one corner — module not level, board does not bear on every joist
5. 46.

   Gate / leaf operation and access checks (if fitted)
   What to look forGate opens and closes through full arc without binding. Self-close functions every time, from any angle. Latch engages with hand pressure. Gap at swing edge ≤ 100 mm. Floor track (if low-threshold) flush with decking. Accessibility per Approved Document M if M is in scope.
   Acceptable whenPer BS 6180 cl.10 and AD M where applicable. Self-close from 90° within 3 seconds. Latch one-hand operation. Threshold ≤ 15 mm where M applies.
   StandardBS 6180:2011 cl.10. Approved Document M cl.2 / cl.4. Approved Document K.
   Common defectsGate binds at the hinge — racked frame from installSelf-close removed because "it slammed" — no longer compliantThreshold height > 15 mm — fails AD MLatch sticks — needs lifting/forcing to operate
6. 47.

   Final clean complete — protective film removed, no debris
   What to look forAll protective film, peel-off coatings and installer labels removed. No fixings, swarf, sealant cartridges, packaging or debris left on the deck or in the soffit. Glass clean. Powder coat free of fingerprints and tape adhesive.
   Acceptable whenModule visually handover-ready. All protection removed (else adhesive bonds permanently under UV). No debris (else drains block on first storm). Cleaning by manufacturer-approved cleaners only.
   StandardManufacturer handover guidance. QUALICOAT — post-install cleaning. CDM 2015 Reg 13(2)(d) — site cleanliness on completion.
   Common defectsProtective film left on edges — bonds under UV, cannot remove without damaging finishSwarf in drainage grate — outlet blocks first time it rainsSealant cartridge left in the soffit void — fire and pest issueTape adhesive residue ringing every post — visible on the elevationSolvent cleaner used on powder coat — gloss reduced
7. 48.

   As-built record, photos and handover pack lodged
   What to look forPhoto record covers: factory build (frame, weld, fire-rated decking class plate, ID plate, lifting points), install (cleat, torque marks, sealant, flashings, thermal break), and verification (flood test, push test, walk-on, final clean). Handover pack issued to the principal contractor / building owner, golden thread updated for relevant buildings.
   Acceptable whenPer CDM 2015 Reg 12(7) Health and Safety File and BSA 2022 cl.62-65 golden thread for relevant buildings. Photo set timestamped and tied to module serial. Handover pack includes DoP, fire performance certs, O&M, maintenance schedule.
   StandardCDM 2015 Reg 12(7). Building Safety Act 2022 cl.62-65 — Golden thread. BS 8579 cl.11 — Information for the building user. UK CPR — DoP retention.
   Common defectsNo photo record — when something fails 5 years in, no evidence of correct installGolden thread not updated — BSA non-compliance on a relevant buildingHandover pack misplaced — homeowner has no maintenance schedule, defects compoundPhoto set covers install only — factory record is absent

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