How to Prepare Your Home for a House Extension in London: A Pre-Start Checklist

Photograph: a completed BCS renovation project at Strone Road, London E12.

It is easy to spend months on the interesting decisions, such as layout, glazing and floor finishes, and then find that the demanding part of an extension is domestic logistics. Where does the washing machine go? Who lets the plasterer in on Thursday? These are small questions that cause friction when nobody answers them until the morning the scaffold arrives.

This guide covers the practical handover between choosing a builder and starting on site. It does not repeat our guide to the extension timeline, which explains each phase once the job is running, or our guide to choosing a house extension builder in London, which deals with the earlier stages. Treat it as the checklist you work through in the final pre-start stage. It is general information, not legal advice.

1. Freeze the scope, the drawings and the inclusions

Confirm which drawing revision is being built from, and make sure everyone on the project is working from the same set. A superseded plan left on site is a genuine source of error.

Agree what is inside the price and what is not. Items that are easy to leave ambiguous include sanitaryware, kitchen units, worktops, tiling, decoration, flooring, external works and garden reinstatement. Citizens Advice recommends a written contract covering the essential details of the work before building work starts, along with checks on permissions and insurance. If you are supplying items yourself, note who orders, stores and checks them, and who is responsible if something arrives damaged.

2. Name one point of contact on each side

Several family members giving instructions to different trades makes a project hard to control. Nominate one person in the household to make day-to-day decisions, and ask who the equivalent contact is on the contractor’s side. Agree the routine too: a single channel for instructions, a short written summary of anything decided in a corridor conversation, and a realistic response window. Decisions that were never written down are hard to rely on later.

3. Working hours, access and who controls the site

Confirm the expected start time, finish time and weekend position, and check them against your local authority’s noisy-works hours and any lease or management-company rules. Then agree the access route: front door, side gate, rear alley, or through the house on protective sheeting. Sort out keys, alarm codes and parking permits in advance rather than on the first morning.

It is also worth knowing who is legally responsible for the site once work starts. HSE guidance on domestic clients explains that under the Construction (Design and Management) Regulations 2015 a domestic client’s duties normally pass to the contractor on a single-contractor project, or to the principal contractor where there is more than one. Ask who holds those duties on your job.

4. Deliveries, materials and the skip

In much of London this needs planning. Work out where a skip can legally stand, whether a permit and bay suspension is required from your borough, and who applies for it. Establish where materials will be stored and how they will be protected from weather and theft. Ask how deliveries will be scheduled and whether anyone needs to be at home to receive them: on narrow streets and in controlled parking zones, a delivery that cannot be unloaded costs everyone time.

5. Utilities and planned interruptions

Ask which services are likely to be disconnected or diverted: water, gas, electricity, drainage, broadband, boiler and heating. Then ask for notice before each interruption. Locate and label your stopcock, consumer unit and gas isolation point with the contractor, and confirm which existing circuits, radiators and outside taps must keep running during the build.

6. Where you will cook and wash

If the extension touches your kitchen, decide before day one where a temporary kitchen will go and what it will contain: a worktop, a sink or accessible tap, fridge, microwave, kettle and somewhere to wash up. Do the same for laundry. Confirm which bathroom or WC stays in use, and whether trades will need access to it.

7. Belongings, dust and noise separation

Empty the work area completely, including lofts, cupboards, under-stairs storage and the garden outside the rear wall. Anything left behind may be moved by someone who does not know it is fragile. Then agree the protection line: where dust screens, temporary doors and floor protection will sit, and which rooms are sealed off. Take down curtains and pictures near the work and move anything valuable or sentimental well away, because dust can travel a long way through a Victorian terrace.

8. Children, pets and visitors

Decide the ground rules while the house is a working site: which areas are out of bounds and how they will be signed or barriered; how pets will be kept away from open doors, tools and materials; and whether the garden is usable and when. If a cleaner, gardener or regular carer attends, tell both them and the contractor.

9. Neighbours and party wall checks

Speak to your neighbours before work starts, not after. Tell them the expected start, the access arrangements and who to contact if something goes wrong.

Separately, check whether the Party Wall etc. Act 1996 applies to your work. GOV.UK publishes an explanatory booklet and example notices covering when notice must be served and the form it takes. Whether the Act applies depends on the specific work, the boundary and the structure, so check the guidance and take professional advice if there is any doubt. Where it does apply, notice periods and any award should be settled before the relevant work begins.

10. Building control route and inspection records

The Planning Portal is clear that planning permission and building regulations are separate matters. Permitted development rights may apply to an extension only where the relevant limits and conditions are met, and most extensions require building regulations approval, subject to specific exemptions.

So confirm two things in writing: which planning route your project relies on and whether any conditions attach to it, and which building control route you are using. Agree who books inspections, who is present for them and where the records and certificates will be kept. Keep those records in your project file so they are available for any later questions about the work.

11. How variations will be handled

Changes are a normal part of building work, and opening up an older London property can reveal something nobody could see beforehand. What matters is the mechanism. Agree that any variation is described, priced and approved in writing before it is carried out, and that the effect on the works is recorded at the same time. That habit reduces the scope for disagreement at the end of the job.

12. Start a dated photo record and a document folder

Before work starts, photograph the whole affected area with dates: existing rooms, garden, boundaries, neighbouring walls and fences, the access route and any existing cracks or damage. Keep one folder, digital is fine, containing the contract, current drawings, planning and building control paperwork, party wall correspondence, insurance details, invoices and written variations. Add a short weekly note of what was agreed.

What cannot be pinned down in advance

Be realistic about uncertainty. Existing foundations, drain runs, timber condition and buried services may remain unknown until they are exposed, and no pre-start conversation can eliminate that. Local factors vary too: skip and parking rules differ by borough, and building control requirements depend on the details of your project. What you can control is the quality of the decisions you make now and the clarity of the record you keep.

Your pre-start checklist