The complete order of operations: how to run a London building project

A building project goes wrong far more often through sequence than through any single bad call. The party wall award sorted after the diggers arrive. The CIL exemption claimed after work started, and therefore lost. The builder priced before the structural design existed, so the price was fiction. None of these are bad decisions — they're good ones taken in the wrong order. This page is the antidote: the complete sequence for a London extension, loft or conversion, from first idea to signed-off completion, with the trap at each step and the guide that goes deeper.

Two principles run through all of it. First, consents and checks come before commitments: you establish what's possible before you pay for design, and you secure design and consent before you price the build. Second, two things must be done before a brick moves — the party wall award and any CIL exemption — because doing them late doesn't just delay the project, it can cost you the right to do them at all.

The sequence at a glance

Steps 1–3: establish, design, get consent

• Feasibility and lease check. Before anything, find out what's actually possible: run the address through a constraint check for conservation area, Article 4 and listed status, and — if you own a flat — read your lease, because flats have no permitted development rights and almost always need the freeholder's consent. This is the cheapest hour you'll spend.
• Appoint a designer. The architect, architectural designer or technologist develops the scheme and usually runs the application. Know what you're hiring — "architect" is a protected title; "designer" is not (see the who-to-hire guide).
• Confirm and secure the consent route. Is it permitted development, the larger home extension prior approval, or a full planning application? Get it right and get it granted — and if you're relying on permitted development, consider a lawful development certificate to prove it. Don't design in detail, or price the build, until the consent position is settled.

Steps 4–6: engineer, building regs, and the lease consent

• Structural engineer. Bring them in while the design is still flexible — the beams, foundations and load paths can change what's achievable, and their calculations are what building control will check.
• Building regulations. Choose your building-control route (local authority or a Registered Building Control Approver) and develop the technical design. Remember building regs apply even to permitted-development work — the two systems are separate.
• Licence to alter (flats only). If you own a leasehold flat, the freeholder's written consent under the lease is a separate gate from planning. Start it early; it runs in parallel with the consents above and routinely takes longer than people expect.

Steps 7–8: the two things that must happen BEFORE work starts

Steps 9–11: contract and build

• Tender and contract. Now — with design, structure and consents fixed — price the work, vet the builder (trade-body membership, references, insurance), and sign a recognised contract such as the JCT Homeowner or RIBA Domestic Building Contract. A price given before this point is a guess.
• Appoint the Principal Designer and Principal Contractor. Where more than one contractor is involved, the law requires these appointments in writing — covering both the CDM health-and-safety role and the building-regulations compliance role. Often the contractor or designer takes them, but the duty to appoint is yours.
• Build and inspect. Pay in stages against completed work, never a large deposit. Book the building-control inspections and never cover up work — foundations, beams, drains, insulation — before it's been seen.

Step 12: completion — the part people forget

Finishing the building is not finishing the project. Completion means closing the paperwork that protects your home's value: obtain the building-control completion certificate; discharge any planning conditions the council attached; submit the CIL completion notice if your project needed one; and, where you relied on permitted development, consider a lawful development certificate to prove it was lawful. Collect every certificate — building control, FENSA, Gas Safe, electrical — and keep them with the deeds. These are exactly the documents a buyer's solicitor will ask for, and the easiest time to have them is now, not under offer years later.

How this connects to your Planning Permission Checker report

This whole sequence starts with step one — knowing what's possible at the address — which is what the free Planning Permission Checker report is for: the conservation area, Article 4 and listed designations that decide your consent route, cited to official data. From there, the professional steps where sequence mistakes cost money — feasibility, consents, the structural and party-wall work — route to Hampstead Chartered Surveyors, an RICS-regulated practice (Firm Reg. 923064). Some projects may also need drawings, planning consultancy, structural engineering, legal advice or other specialist input; and for the build, the who-to-hire guide arms you to choose a builder safely.