Building Envelope · 12 checks

Windows & Doors
QA inspection checklist

Window and door installation 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.

Delivery & Inspection

  1. 1.
    Units match schedule — type, size, colour, ironmongery
    What to look forSchedule cross-checked against label on each unit — opening type (casement, sash, tilt-turn), size, colour (RAL/woodgrain), glazing build-up, hardware. Hand of opening matches schedule.
    Acceptable whenPer door/window schedule. Manufacturer label with size, opening type, U-value, hardware code on each unit. Tolerances ±2 mm on overall dimensions per BS EN 14351-1.
    StandardBS EN 14351-1:2006+A2:2016 — Windows and doors product standard. BS 644 (timber windows). BS 6375-1 (weather performance).
    Common defectsWrong hand — left-hung delivered where right-hung specifiedTrickle vents missing where required for ventilation compliance (Approved Document F)Wrong RAL — production substituted, visible at handoverU-value worse than specified — thermal calc failsStandard glazing where laminated/toughened required for safety glass zones
  2. 2.
    No damage to frames, glazing, or hardware
    What to look forInspect under raking light. No scratches on visible faces, no chips on glass edges, no dents in profile. Hardware undamaged (handles, hinges, locks). Sealed unit not blown (no condensation between panes).
    Acceptable whenPer BS EN 14351-1 / GGF: no scratches > 75 mm visible at 3 m. No edge chips on glass > 2 mm. Hardware undamaged. Inspect on delivery before signing for goods.
    StandardBS EN 14351-1. GGF Glazing Manual. CWCT Standard.
    Common defectsEdge chips on glass — handling damage, will fracture in serviceFrame scratched and field-touched up — visible mismatchHardware bent — sashes do not closeFailed IGU on delivery — condensation between panes (rare but happens)
  3. 3.
    CE/UKCA marking and performance certificates available
    What to look forCE/UKCA mark on label. DoP (Declaration of Performance) provided with delivery. Includes: U-value (Uw), air permeability class, watertightness class, wind resistance class, security class (PAS 24 if specified). Notified body number visible.
    Acceptable whenCE/UKCA per Construction Products Regulation. DoP per BS EN 14351-1. Performance class per spec — typical residential: Uw ≤ 1.4 W/m²K, air permeability Class 4, watertightness Class 9A, wind resistance Class C5. Security PAS 24:2022 for new dwellings.
    StandardBS EN 14351-1:2006+A2. PAS 24:2022 — Enhanced security. Construction Products Regulation. Approved Document Q (security in dwellings).
    Common defectsNo DoP provided — non-compliant with Building RegsPAS 24 not certified for the actual hardware combination suppliedU-value worse than design after re-spec — Approved Document L failTest certificate covers different size/configuration than installed

Installation

  1. 4.
    Frames plumb, level, and square
    Record: Deviation (mm)
    What to look forPlumb in two axes, level on cill, square on diagonals (corner-to-corner difference < 5 mm). Frame not "wracked" — visible in tight diagonals or sash binding. Reveals symmetrical.
    Acceptable whenPer BS 8000-7 / BS EN 14351-1: plumb ±2 mm in 1 m, level ±2 mm, diagonals ±5 mm. Frame must permit smooth opening without rubbing. Reveal margins ±5 mm.
    StandardBS 8000-7:1990 — Workmanship — Glazing. BS EN 14351-1. NHBC Standards 6.7.
    Common defectsFrame out of square — sash will not latch or rubs at one cornerCill not level — water sits on one end, corrosion of fixingsFrame plumb but reveals unequal — bricklayer's opening was wrong size, packed asymmetricallyFrame distorted by over-tightening fixings
  2. 5.
    Fixings correct type and spacing
    What to look forFixings (frame screws, anchors, lugs) of type per manufacturer's installation guide. Spacing typically 600 mm centres, ≤ 250 mm from corners. Through-frame fixings into solid masonry, not bedded mortar.
    Acceptable whenPer manufacturer's installation manual / BS 8213-4 (windows). Frame fixing spacing ≤ 600 mm, ≤ 250 mm from corners. Anchors with min 50 mm engagement into solid masonry. Pull-out tested where specified.
    StandardBS 8213-4:2016 — Code of practice for installation of windows. Manufacturer's installation guide.
    Common defectsFixings into mortar joints only — pull-out, frame loosensSpacing > 600 mm — frame deflects under wind loadPlastic plugs in autoclaved aerated concrete (AAC) — wrong fixing typeNo fixings within 250 mm of corner — frame opens at corners under loadFixings over-tightened, distorting frame
  3. 6.
    Cavity closers installed
    What to look forCavity closer continuous around full perimeter of opening (including head and cill). Closes the cavity to prevent thermal bridge. Compatible with insulation in cavity. DPC continuous.
    Acceptable whenPer NHBC Standards 6.1: cavity closer with thermal performance per Approved Document L (typical λ < 0.04 W/mK). Continuous around opening, providing thermal break between inner and outer leaf.
    StandardNHBC Standards 6.1 and 6.7. Approved Document L. Approved Document C (resistance to moisture).
    Common defectsNo cavity closer — cold bridge, condensation around revealWrong type — non-insulated PVC closer where thermal break neededCloser not continuous — gaps at cornersDPC interrupted by closer — water bridge to inner leaf
  4. 7.
    Sealant applied continuously at perimeter
    What to look forSealant joint continuous around external perimeter. Tooled smooth, no breaks. Inner side often sealed too with breathable sealant or expanding tape (membrane principle — air-tight inside, weather-tight outside).
    Acceptable whenPer BS 8000-7 / BS 6213: external sealant joint continuous, depth ½ width, with backer rod for joints > 6 mm. Use sealant per BS EN 15651-1 façade grade.
    StandardBS 6213:2000. BS 8000-7. BS EN 15651-1.
    Common defectsSealant skipped at corners or behind cill horns — water entryAcetic-cure silicone on aluminium — corrosionNo backer rod in deep joint — three-sided adhesion, splitsInternal seal omitted — air infiltration, draughtsSealant applied to dusty/wet surface — no adhesion
  5. 8.
    Threshold correctly detailed and sealed
    What to look forThreshold to manufacturer's detail. Cill upstand to outside (water shed away). DPC behind threshold lapped over external cill. Step at threshold per Approved Document M (≤ 15 mm at level access).
    Acceptable whenPer BS 8213-4 / NHBC: threshold with weather seal, cill projecting beyond face of wall by 25 mm minimum with drip groove. Approved Document M level access threshold ≤ 15 mm with chamfer. DPC lapped over cill.
    StandardBS 8213-4:2016. NHBC Standards 6.7. Approved Document M.
    Common defectsThreshold step > 15 mm where level access requiredNo drip groove on cill — water tracks back underDPC not lapped over cill — water enters wall at cill beddingCill bedded direct on brickwork without setting blocks — settles, cracksWeather seal compressed permanently — no longer seals

Function & Finishing

  1. 9.
    Opening lights operate freely and close tight
    What to look forSash opens/closes smoothly, no binding, no excessive force. Compresses gasket evenly all round when closed. Restraint stays operational. Multi-point locks engage at all points.
    Acceptable whenPer BS EN 12400 (cycle test) / BS EN 1191. Operating force ≤ 100 N. Gasket compresses uniformly. Locks engage at all points without forcing.
    StandardBS EN 1191:2012 — Resistance to repeated opening and closing. BS EN 12400:2002 — Mechanical durability.
    Common defectsBinds at one corner — frame out of squareMulti-point lock engages partially — top or bottom point not alignedGasket compressed unevenly — air leak, fails air-testRestrictor (Approved Document K) bypassed by handle reversalHinge sag on heavy door — needs pivot adjustment
  2. 10.
    Locks, handles, and restrictors functional
    What to look forLocks turn smoothly, key operates from both sides if specified. Handles secure. Window restrictors limit opening to 100 mm where required (Approved Document K). Egress windows operate without key.
    Acceptable whenLocks per BS 3621 (BSI Kitemark for insurance). Restrictors per BS 8213-1 — child safety (≤ 100 mm gap), or escape window operable without key/tool. Hardware certified PAS 24 for new dwellings (Approved Document Q).
    StandardBS 3621 — Thief resistant lock assembly. BS 8213-1:2004 — Code of practice for windows and doors. Approved Document K (height limits/restrictors). Approved Document Q (security).
    Common defectsRestrictor missing on opening above 1.4 m floor level — child safety riskEgress window requires key — illegalLock not BS 3621 — insurance voidHandle mounted at wrong height — Part M failPAS 24 hardware spec not as tested — security claim invalid
  3. 11.
    Trickle vents open and operational
    What to look forTrickle vent fitted to head of frame per Approved Document F (where required). Slider operates freely. Vent area as scheduled (per air-flow calculation). Insect mesh present and unblocked.
    Acceptable whenPer Approved Document F (England 2021): habitable rooms typically 8000 mm² equivalent area; kitchens, utility, bathrooms 4000 mm². Vent operates freely. Marked with permanent open/closed indication.
    StandardApproved Document F (Means of ventilation). BS 5925 (natural ventilation).
    Common defectsNo trickle vents fitted — fail Approved Document FInsect mesh missing — bug ingress, gets blockedVent painted shutVent area undersized for roomVent on internal door without weather seal
  4. 12.
    Fire doors — intumescent strip, closer, signage correct
    What to look forIntumescent strip continuous around door edges (3 sides minimum), no breaks at hinges or strike plate. Cold smoke seal where required. Self-closing device, latching positively. Signage "Fire door — keep shut" / "Fire door — keep locked shut".
    Acceptable whenPer BS 8214:2016 / BS EN 1634-1: intumescent strip continuous, undamaged, correct width for fire rating (FD30 = 10 mm typical, FD60 = 15 mm). Closer per BS EN 1154. Gap to floor ≤ 8 mm under door, ≤ 4 mm at frame. Signage per BS 5499.
    StandardBS 8214:2016. BS EN 1634-1 — Fire test. BS EN 1154 — Closers. BS 5499-5 — Signs. Regulatory Reform (Fire Safety) Order 2005.
    Common defectsIntumescent strip missed at corner or hinge cut-outGap to floor > 10 mm — no smoke seal can bridgeCloser disconnected because slamming complaints — fails complianceHinge sizes/numbers different from tested assembly — invalidates fire ratingSignage missing or wrong wording for door typeDoor shut tight but not latched — closer power inadequate

Questions people ask

What is a windows & doors 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 14351-1:2006+A2:2016, BS EN 14351-1. GGF Glazing Manual. CWCT Standard., BS EN 14351-1:2006+A2. PAS 24:2022, BS 8000-7:1990, BS 8213-4:2016, NHBC Standards 6.1 and 6.7. Approved Document L. Approved Document C (resistance to moisture).. 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?

12 checks across 3 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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