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    NHBC Key Stage Inspection Checklists

    367 checks across 16 stages — from the open trench to the Cover Note. Each checklist covers what the inspector looks at, when the visit is triggered, and the items that get written up most often.

    Reviewed by the ProPlot site team

    Key stage inspections exist because most of a house disappears. Reinforcement, cavity trays, wall ties, drainage falls, cavity barriers and insulation are all concealed within days of being installed, so the warranty provider inspects at the points where they can still be seen. Miss the window and the only routes back are opening up finished work or producing evidence you should have captured at the time.

    The checklists below follow the build sequence. Use them as your own walk before you book each visit — most of what an inspector writes up is visible to anyone who looks for it with a list in hand.

    Use them on site

    The inspection sequence

    1. 1Excavation & foundations — 21 checksAfter excavation is complete and any reinforcement is fixed, but before concrete is placed. Most warranty providers want at least 24–48 hours' notice, and the trenches must still be open when they arrive.
    2. 2Drainage — 20 checksWhen the below-ground runs are laid and jointed but before bedding is surrounded and backfilled. On adopted runs, book alongside the water authority inspection so the trench is only opened once.
    3. 3Basement / lower ground — 28 checksTwo moments matter. Before the retaining structure is poured, so reinforcement, cover and joint details can be seen; and after the waterproofing is installed but before it is covered by finishes or backfill. On most plots the inspector will want both, so plan the programme around two visits rather than one.
    4. 4Ground Floor & Slab — 19 checksAfter the floor build-up is complete — membrane, insulation, mesh and service penetrations — and immediately before screeding or pouring the slab.
    5. 5Superstructure — 22 checksDuring the masonry lifts and again once the wall plate is strapped down, before the roof structure closes off access to the cavity and the party wall head.
    6. 6Timber Frame Erection — 21 checksAs the frame is erected and before the breather membrane is covered by the outer leaf, insulation or internal linings. On multi-storey frames, at each lift.
    7. 7Roof — 22 checksFirst when trusses are erected, braced and strapped and before felt and battens go on. Second when the covering is complete but the scaffold is still standing.
    8. 8Windows and External Doors — 24 checksAs each plot is glazed, following the superstructure inspection. The opening detail must be checked before the unit is fitted and the perimeter seal before plastering.
    9. 9Insulation & Airtightness — 23 checksContinuously through the fabric stages, with a formal check before insulation is covered — behind the outer leaf, in the roof, and at pre-plaster. The airtightness test itself is carried out once the envelope is complete.
    10. 10First Fix — 28 checksWhen carcassing, studwork and all first fix services are complete, before the insulation and airtightness layer goes in and well before boarding.
    11. 11Fire Stopping — 22 checksContinuously through the build — at cavity closing, at each floor and compartment penetration during first fix, and finally in the roof void before the loft is closed. Checked formally before boarding.
    12. 12Pre-Plaster — 21 checksWhen first fix is complete and insulation is installed, immediately before plasterboard goes on. Book it so boarding can start the same week — this is the visit that most often holds up a programme.
    13. 13Second Fix — 31 checksAfter plastering has dried and decoration has started, running through to the pre-handover inspection. Usually the longest and most congested stage in the plot programme.
    14. 14External Works & Pre-Handover — 23 checksOnce the plot is released from construction traffic and surfaces are laid — before the pre-CML visit, because incomplete externals are one of the most common reasons a CML inspection is aborted.
    15. 15Pre-handover — 22 checksWhen the plot is complete, commissioned and clean, before legal completion. Allow at least a week between booking and the intended completion date so there is time to clear anything raised.

    Applies at every visit

    General quality checklist

    Workmanship, tolerances, materials, weather protection, concealed-work evidence and closing out previous items — the weekly walk that keeps the stage visits short.

    Inspection FAQs

    The set visits a warranty inspector makes during a new-build: foundations before the pour, drainage before backfill, the ground floor before the slab, the superstructure during the masonry or frame, the roof at structure and covering, pre-plaster before boarding, and the final pre-CML visit before handover. Exact visit numbers vary by provider and site risk.

    Most warranty providers ask for at least 24–48 hours. Pre-pour and pre-backfill visits should be booked the day before the work is due, so the excavation or trench stays open no longer than necessary.

    A defect or omission the inspector records against the plot because it departs from the warranty standards. Items must be corrected, and unresolved or repeated items affect the site score and how often you get inspected.

    No. Building control checks compliance with the Building Regulations and issues the completion certificate; the warranty provider checks their own standards and issues the Cover Note lenders require. Both visits are needed.

    Yes. The checks are drawn from the Building Regulations Approved Documents and common warranty standards, so they apply across providers. Always cross-check against your specific provider's technical manual for anything provider-specific.

    Every checklist, on your phone, on site

    ProPlot turns these lists into live audits — tick items off, attach GPS-stamped photos, raise snags against a plot and share the report with your inspector.

    Create a free account Critical construction dimensionsBuild stage quality libraryHow the inspection app works

    Quality Intelligence

    Free, cited reference library for UK housebuilding quality — search it, or ask a question and get the citation back with the answer.

    Search the standardsAsk a questionBuild stage libraryCritical dimensionsCommon defectsAll guides

    Above and beyond: protection as a programme discipline

    Passing the inspection and handing over a plot the customer is delighted with are two different standards. Capping pipe ends, labelling water feeds, fitting backbox protectors before drylining, covering wall heads overnight, laying floor protection before boarding — none of it appears on a warranty inspector's list, and all of it decides whether your snag list is two items or forty. Every stage checklist below now carries its own protection section, with what to do, why it costs you if you skip it, and the point in the sequence it has to happen.

    Before boarding

    Label water feeds both ends, cap pipe ends, backbox protectors, photograph every wall, mark noggins.

    As the walls go up

    Cover wall heads and party wall insulation, protect reveals and cills, clean down the same day.

    Approaching handover

    Floor and stair protection, labelled valves and consumer unit, a walk at customer eye level.

    Externals and presentation

    Protect new paving and gullies from site traffic, hold the frontage from scaffold-down.

    Related guides

    The NHBC inspection process, start to finish

    Registration, notice periods, key stage versus risk based visits, and the certificates at the end.

    Reportable Items and Quality Common Scoring

    What an RI is, how Damage Potential is weighted, and how to close one out properly.

    Apartment and block inspections

    Compartmentation, fire stopping, sound testing, communal areas and phased handovers.

    Snag lists with GPS photo evidence

    How to record and close out defects with evidence that stands up at handover.

    NHBC stage inspections on site

    Running key stage inspections and keeping the paperwork straight.

    Warranty providers compared

    How NHBC, Premier Guarantee and LABC Warranty differ on standards, inspections and certificates.

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    Our sourcing, review and correction policy — what we cite and what we will not republish.

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