Complete renovation of a house

With a main contractor, one builder prices the whole scope, employs or subcontracts the trades and is responsible for the result. You deal with one business and one contract. It usually costs more than hiring trades directly, because the builder carries the coordination and the risk of trades not turning up.

Managing the trades yourself can save money, but you then plan the sequence, order materials, arrange Building Control inspections and absorb every delay. Under the Construction (Design and Management) Regulations 2015, the HSE explains that a domestic client's duties normally pass to the contractor, or to the principal contractor where there is more than one; if you have not appointed one, they fall on the contractor in control of the work. When several trades work independently, it should be clear who that is.

With an architect or surveyor leading, the designer writes the specification, obtains approvals, and may administer the building contract, checking work and valuations before you pay. That adds fees but brings an independent eye, which is useful on large or complicated houses.

Source: legislation.gov.uk

Builders can only price what they are told. A schedule of works lists each room and each element with the work required: remove and dispose, repair, replace, supply and fit. It names products or a standard, such as the type of flooring or the sanitaryware range, or includes a provisional sum where you have not yet chosen. Without it, two builders will price two different houses.

Provisional sums are honest placeholders, but a quote full of them is only an estimate. Try to fix the choices that drive cost before you sign: kitchen, bathrooms, flooring, windows and the heating system.

Living in a house while it is completely renovated is possible, but it slows the work and it is hard on the people living there: no heating for days, no kitchen for weeks, dust everywhere. Builders often price a vacant house lower because they can work in any room at any time. If you stay, agree which rooms stay usable, where the temporary kitchen goes and when water and power will be off.

Tell your home insurer before work starts. Policies often have conditions about major building work and about houses left unoccupied, and the builder should hold its own public liability and contract works insurance, which you can ask to see.

Changes happen on every renovation: rot behind the plaster, a decision to move a doorway, a different tile. The contract should say that any variation is priced and agreed in writing before it is carried out. Keep a running list with the prices, so the final account holds no surprises.

Pay in stages linked to completed work, such as strip-out finished, first fix completed and inspected, plastering finished, rather than by the calendar. A modest deposit for materials is normal; paying most of the price before the work is done is not. Many contracts also hold back a small retention until snagging is complete.

• the schedule of works or drawings and specification the price is based on
• provisional sums, with what each covers
• programme with key dates and who applies to Building Control
• certificates to be handed over: electrical, gas, windows, Building Control
• stage payment plan, retention and how variations are agreed
• insurance, site protection, waste removal and working hours

A complete renovation is the time to check the incoming supplies. Moving a gas meter, upgrading an electricity supply for a heat pump or car charger, or replacing a lead or shared water supply pipe all involve the network operator or water company, and their lead times can be longer than the builder's. Ask the builder early which applications are needed and who makes them.

Windows, kitchens and bespoke joinery also take weeks to manufacture. Order them on the builder's programme, not after the walls are plastered.

You describe the house and the scope once. We show the job to renovation firms in your area without your name or contact details, and one firm, and only one, can buy it. It pays Offrano, and you pay nothing. Before the firm sees your details, we email you its name, address and phone number.

A large renovation is a big commitment for a builder too, and there is no guarantee that a firm will take the request; if none does within 21 days, it is withdrawn. You are free to decline the quote and to approach other builders. Offrano checks only that the buyer is a registered business, so ask to visit a finished project and speak to the client.