Getting quotes for an extension or building work
This is the largest sum most people ever hand to a trade, and the one where quotes are least comparable, because two builders can price entirely different jobs from the same conversation.
An extension quote should name the drawing revision it priced and say where the price ends: shell, plastered or finished. Agree a rate for extra foundation depth before it is needed. Planning and building control are different things and the completion certificate is what a buyer's solicitor asks for.
What a real quote itemises
Ask for these in writing. Somebody who works properly will be glad to list them, because it is how their price gets justified against a cheaper one.
- The drawings the price is based on. Every quote should name the drawing revision it priced. Without that, you are comparing prices for different buildings.
- Where the price ends. Shell, plastered, or finished including decoration, flooring, kitchen and bathroom fit. This single line explains most of the gap between two quotes.
- Groundworks and the unknown. Foundation depth is not knowable until the ground is open. Agree a rate for additional depth up front rather than a lump that assumes the best case.
- Structural elements. Steels, and who is paying for the structural engineer's calculations.
- Building control. Which route, who is applying, and whose fee it is.
- Services. Drainage, electrics, heating and whether extending the existing system is included or a separate trade you must find.
- Stage payments. Tied to completed stages you can see, never to dates. See below.
Planning and building control are different things, and both matter
Planning permission is about whether you may build it; building control is about whether it is built safely and to standard. Many extensions fall under permitted development and need no planning permission, and almost all of them still need building control. A completion certificate from building control is what a buyer's solicitor asks for. Builders have no statutory register, so the checks are the company on Companies House, current public liability insurance, and whether they hold contractors' all risks cover for the works themselves.
Stage payments against dates rather than stages
The structure that protects you is simple: payments released against completed, visible stages, never against a calendar, and never a large sum before work starts. A deposit for materials is normal; a third of the contract value before anybody arrives is not. Keep a retention, typically five per cent, for a period after completion so there is something left to pay when the snagging list is done. Agree all of this in writing before the first payment, because afterwards you have no leverage to change it.
Three quotes, and the general checks
Get three for anything beyond a small job. You are not looking for the cheapest, you are looking for the outlier. Then run the same three checks you would for any trade: the registration their trade requires, current public liability cover, and the company on Companies House. Those checks are here.
Can Tradelynx introduce you to one?
We only route work in Bournemouth, Portsmouth and Southampton, and only in the trades we have people for: right now that is builder, carpenter, electrician, handyman, landscaper and roofer / guttering. Everywhere else, and in every other trade, we are still building our supply and would rather say so than pretend.
What is worth keeping afterwards
The building control completion certificate, the structural calculations, the final drawings as built, and photographs of the groundworks and services before they were covered.
A HomeLynx Passport is free and covers every UK home, whether or not we route work near you. If you already have somebody you trust, they can run your job through Tradelynx wherever you both are.