House Extension Handover Checklist for London Homeowners

House Extension Handover Checklist for London Homeowners | BCS Builders London

In short

Handover is where your extension stops being a building site and becomes part of your home. It brings together three separate things: a visual walk‑through that produces a written snag list, a contractual handover step defined by your building contract, and the building‑control or competent‑person records that apply to the work. Taking them in order — contract and scope, walk‑through, records, then a written close‑out list — keeps the day organised and leaves you with evidence you can use later.

This guide is general information for London homeowners finishing an extension, and it is not legal advice. It follows our pre‑start checklist, which covers the same project from the other end. Here we deal with the closing weeks: what to look at, what to write down, which records to chase, and how to leave the job with a clear list of anything outstanding.

Three terms that are not interchangeable

Snagging, handover and completion are often used interchangeably, but the difference decides what you chase and who you ask.

Visual snagging is your own written record of finished, visible work. A snag list is a practical record between you and your contractor; it is not building‑control approval and not a specialist inspection.
Contractual handover is the point your building contract treats the work as complete, sometimes called practical completion. What that means depends on your contract and project; there is no single legal threshold covering every extension.
Building‑control completion is the regulatory side. GOV.UK explains that many kinds of home building work need Building Regulations notification or approval unless a competent‑person route applies, and that compliance records can matter when you sell.

A good walk‑through can finish with paperwork still outstanding, so treat the two as parallel tasks.

Step 1 — Read the contract and current scope

Before you walk the extension, re‑read what you actually agreed. Your original quotation or contract sets the scope; any variations agreed during the build change it. If a fitting was swapped or a wall moved, that decision belongs in the file, not in your memory.

Bring three things to the walk‑through: the current scope including variations, the approved drawings if you have them, and a phone for photographs. Reading it first prevents the two conversations that waste handover day — arguing about work never in scope, and missing work that was.

Step 2 — Walk through in daylight, room by room

Book the walk‑through for a bright part of the day and allow proper time. Daylight across a wall shows differences a ceiling light flattens out. Work room by room in a fixed order; jumping between spaces is how items get missed.

Within each room, use the same sequence: floor, walls, ceiling, openings, fittings, then the junctions where one material meets another. Step outside too and look at external walls, reveals, rainwater goods and anything the works touched, such as paths and fences.

Step 3 — Check visible finishes and junctions

You are looking at what is visible and reachable, not diagnosing structure or hidden services. That is the practical limit of a homeowner walk‑through, and visible surfaces and junctions are what it covers.

Paint and plaster: coverage, edges, and lines where a wall meets a ceiling or skirting.
Floors: level changes at thresholds, gaps at the perimeter, and the transition into existing rooms.
Doors and windows: they open, close and latch without forcing, and the seals and beads are seated.
Tiling, sealant and trims: alignment, consistent joints, and continuous sealant at baths, basins and worktops.
Old‑to‑new junctions: where the extension meets the original house, inside and out.
Cleanliness and making good: protective film removed, debris cleared, and any damage to existing finishes noted.

If something looks structural, damp‑related or electrical, record it as an observation and ask the appropriate trade to assess it rather than judging it yourself.

Step 4 — Test normal homeowner controls

Test the everyday functions, safely and normally: reachable light switches and sockets, taps and drainage at each new outlet, the flush, extract fans, heating controls and radiator valves, and door and window ironmongery. Ask for a short demonstration of anything unfamiliar.

Do not open consumer units, remove covers, work at height or interfere with gas or electrical equipment. Testing means using the installation as you will day to day, then reporting anything unexpected.

Step 5 — Write a workable snag record

A useful snag list is factual, located and owned. Vague entries create arguments. Record each item with six fields.

Field	What to record
Room or location	The room and exact position, such as the rear elevation reveal.
Photograph	A dated photograph showing the item and enough context to find it.
Description	What you can see, in plain factual language, without assuming a cause.
Owner	The person or company agreed as responsible.
Target date	A date agreed in the meeting, not a vague undertaking.
Status	Open, in progress, resolved or disputed, with the date it changed.

Share the list in writing on the same day, in a format both sides can add to. Citizens Advice recommends keeping issues with home improvements in writing and using photographs as evidence, which is what a snag record gives you.

Step 6 — Identify the completion record and certificates

There is no universal certificate pack for an extension. What exists depends on the scope, the approval route and the trades involved, so ask early which records your project generates and who issues them.

Building control. Where the work went through a building‑control body, LABC’s guidance describes a completion certificate being issued after a final inspection where the work followed approved plans and no apparent contraventions remained. An absent certificate may mean no final inspection took place, or that something is outstanding.

Competent‑person schemes. GOV.UK explains that where work is covered by a competent‑person scheme, a registered installer should notify the local authority and issue or arrange the relevant compliance certificate. LABC adds that trade‑scheme certificates may need to be obtained from the scheme operator rather than from building control.

Electrical work. Electrical Safety First explains that fixed electrical work must comply with the Building Regulations, and that where a registered electrician carries out relevant work you may expect an Electrical Installation Certificate or a Minor Works Certificate and, where applicable, a Building Regulations Compliance Certificate. Check which applies to your job.

Other trades. If the work involved gas appliances, heating alterations or plumbing, ask which records apply and who issues them, because requirements depend on the installation and the scheme rather than a standard document.

Step 7 — Collect the documents that apply to your job

Manuals, warranties, spare materials, approved drawings, variation records and as‑built information are project and contract dependent, not universal legal requirements. Ask what has been produced for your job, then file what exists.

Product manuals and registration details for appliances, controls or rooflights that came with them.
Any manufacturer or installer warranty documents provided, with their start dates and conditions.
Approved drawings and the record of variations agreed during the build.
As‑built information where it was produced, including anything showing service routes.
Leftover paint, tiles or flooring, if spares formed part of the agreement.

Keep everything in one folder, digital or paper, with the snag record and completion paperwork. Our guide to extension timelines shows when these documents appear during a build, so you can request them at the right moment.

Step 8 — Record what is outstanding

Close the meeting with a single written summary: items resolved on the day, items still open with owners and dates, records received, records still expected, and any review still to come. Send it to your contractor the same day and ask them to confirm or correct it.

If something comes to light once the space has been used, arrange a second, shorter walk‑through; living in a room shows up what one inspection misses.

If you and your contractor disagree

Citizens Advice suggests raising problems with the trader who arranged the work, keeping the issue in writing and using photographs as evidence. Set out what you observed, refer to the agreed scope and ask for a response.

On payment, follow your written contract. This guide does not tell you to release or withhold a final payment, because that depends on your agreement; if a dispute develops, take independent advice.

The final checklist

Keep this on your phone for the walk‑through.

Read the contract and the agreed variations.
Walk every room in daylight, plus outside.
Check visible finishes and old‑to‑new junctions.
Test normal controls safely; open nothing.
Log each snag with location, photo, description, owner, date and status.
Ask which completion record and trade certificates apply.
Collect the manuals, warranties and drawings that exist for your job.
Send a written close‑out summary the same day.
Arrange a follow‑up review if anything emerges in use.
Keep disagreements in writing and follow your contract.

Official sources

Read the guidance directly:

BCS Builders London designs and builds house extensions across London. If you are planning work rather than finishing it, our guide on choosing a house extension builder covers the earlier decisions, and you can get in touch to discuss a project.

Photograph: a BCS project at Sanderstead Avenue, London.

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