Which Trades Do You Need for a London Renovation? (2026)

Why do the drawings have to come before the trades?

Because a quote is only meaningful against a defined scope. Ask three builders to price a rear extension from a description and you will get three prices for three different buildings — one has assumed a standard door set, one has allowed for structural glazing, one has not priced the drainage diversion at all. None of them is lying; they are each filling the gaps in the brief with their own assumptions, and you have no way to see which assumptions differ. Put the same measured, dimensioned drawings in front of all three and the prices become comparable for the first time.

The second reason is regulatory. Planning permission and building-regulations approval are both decided on drawings, not on conversations, and building control signs off against an approved set. Starting work before that set exists means either a stop-start programme while approvals catch up, or work that later has to be opened up and corrected. Neither is cheap, and both land on the homeowner rather than the trade.

Who are the professionals before anyone picks up a tool?

Three roles sit ahead of the building work, and skipping any of them tends to be discovered later at cost. They are design, structure, and — where a boundary is involved — party wall.

None of these three are trades in the site sense. They produce paper, and the paper is what the trades build from and what the council approves. Their combined fee is a small fraction of a London build budget and the part with the highest leverage on everything after it.

What order do the trades work in?

The sequence below is the one nearly every domestic project follows, and it is not a matter of preference. Each stage buries the one before it: first-fix cabling disappears behind plasterboard, plaster disappears behind paint, and anything installed out of order has to come back out.

The most common scheduling error is booking the finishing trades to a date fixed before the structural stage started, then compressing them when the structure overruns. Plastering and decorating sit at the end of the programme, which is exactly where all the earlier slippage accumulates, and they are the two stages whose quality is most visible in the finished house.

• Demolition and strip-out — including opening up to confirm what the survey could not see
• Structure — foundations, steelwork, load-bearing alterations, roof
• Weathertight envelope — roof covering, windows and external doors
• First fix — electrical cabling, pipe runs, ductwork, studwork and floor structure
• Plastering — boarding, skimming, rendering and dry lining
• Second fix — sockets, switches, radiators, sanitaryware, kitchen, internal doors
• Decoration and flooring — the last wet trades and the finishes everyone actually sees
• Snagging and sign-off — building control completion, electrical and gas certificates

Which trades are legally gated, and how do you check?

Most trades in the UK are unregulated: anyone may call themselves a builder, a carpenter, or a tiler. A few areas are not, and on these the paperwork is a legal requirement rather than a badge of quality.

Checking takes minutes and is worth doing directly rather than accepting a logo on a van or a website. Each of the schemes below publishes a public register, and a registration number that does not appear on it is the end of the conversation.

• Gas — anyone working on gas appliances or pipework must be on the Gas Safe Register; ask for the card and check the number
• Electrics — fixed electrical work in a dwelling is notifiable under Part P, so use an electrician registered with a competent-person scheme such as NICEIC or NAPIT
• Party wall — a party wall surveyor should be RICS-regulated or a member of a recognised party wall faculty
• Design — a chartered architectural technologist is MCIAT-registered with CIAT; an architect is ARB-registered
• Insurance — every trade on site should hold current public liability cover, and you should see the certificate rather than be told it exists

Who are the finishing trades, and why do they matter more than people expect?

Structural work is judged by whether it stands up. Finishing work is judged by eye, every day, for as long as you live there. That asymmetry is why the last third of a renovation deserves more attention than it usually gets — and why the trades in it are worth engaging early rather than whoever happens to be free in the week they are needed.

Plastering is the clearest example. It sits after first fix and before decoration, and the flatness of the wall it produces sets the quality of every coat of paint that follows. It is genuinely skilled work with a long apprenticeship behind it, and poor plastering cannot be corrected by a decorator — it shows under raking light forever. A dedicated firm such as London Plastering Service handles skimming, rendering and dry lining across London, and the better ones are booked weeks ahead, which is precisely why they should be lined up while the structure is still going in rather than phoned once the boards are up.

Bathrooms and kitchens are the other place where specialists outperform generalists. A bathroom packs drainage falls, electrical zones, waterproofing and tiling setting-out into four square metres, and the parts that fail are the ones nobody can see once it is finished. A specialist renovation firm such as London Renovate handles design, supply and installation of bathrooms and interior finishes as a single package, which removes the familiar argument about whether a fault belongs to the fitter or the supplier. Whoever you use, brief them from the drawing rather than from a mood board — the layout has to work with the soil stack before it can look like the picture.

How many quotes should you get, and what should you compare?

Three written quotes per trade, all priced against the same drawings and specification, is the working minimum. Fewer than three and you have no sense of the market rate; more than about five and you are spending your own time for diminishing returns, and trades notice when they are one of eight.

Compare scope before price. A quote well below the others is usually cheaper because something has been left out — the survey, the structural design, the making-good, the waste removal, the VAT — and finding out which takes a single question. Compare what happens when things change, too: a fixed price with a named variations process is worth more than a slightly lower price with no mechanism for the inevitable moment the floor comes up and something unexpected is underneath it.