How a design-and-build project runs
A design-and-build contract means one company is responsible for both the design and the construction, and for delivering the finished building for an agreed price. This guide sets out what happens at each stage of a project with us, what we need from you, and what you will be asked to decide.
1. First visit and survey
We visit the building, walk it with you and scan it. The scan gives us a measured plan, room areas and a photographic record of the condition on the day. If the building is occupied, we agree access with the occupier first.
What we need from you: access to every room, and any drawings, planning decisions, leases or surveys you already hold.
2. Feasibility and budget
Before design work starts, we test whether the scheme works. For a conversion or a development that means a development appraisal: build cost, fees, finance and end value, with the source of every figure shown. For a refurbishment or an extension it means a costed scope with a range, so you can decide how far to go.
3. Design and approvals
We prepare the drawings and, where needed, appoint and coordinate the structural engineer, the acoustic and fire consultants, and any specialist designers. Approvals come in three kinds:
- Planning permission, from the council, where the work changes the use or the outside of the building. Many extensions and conversions fall under permitted development and do not need an application; we check this first.
- Building Regulations approval, from Building Control, for the construction itself: structure, fire, sound, ventilation, energy, drainage and access. We act as principal designer under the CDM Regulations 2015 and carry the package.
- Party wall agreements with neighbours, where the work affects a shared wall or is close to their foundations.
Timescales depend on the council. A planning application typically takes eight weeks from validation; a Building Regulations full plans application four to six weeks. We set the programme around these.
4. Contract
With the design fixed, we issue a fixed price and a programme. The contract sets out the scope, the price, the payment stages and the dates. Payment is in stages tied to progress, usually on instruction, at defined milestones and at practical completion. Retention is agreed case by case.
Under CDM 2015 we are appointed principal contractor for the works. Before we start on site we prepare the construction phase plan, arrange welfare, and notify the Health and Safety Executive if the project is large enough to require it.
5. On site
One programme runs the job and one person is your point of contact. You receive a progress report every week with photographs, and every inspection by Building Control, the engineer or a specialist is recorded against the stage it belongs to. Variations are priced and agreed before work proceeds. Site rules, access hours and neighbour communication are agreed at the start.
6. Completion and handover
Practical completion is the point at which the works are finished and the building can be used. At handover you receive, in one digital record:
- The Building Regulations completion certificate.
- Electrical, gas and other installation certificates, and product warranties.
- The health and safety file required by CDM 2015.
- The as-built drawings and a 3D scan of the finished building.
7. After handover
A defects period follows completion, usually twelve months, during which we return to put right anything that fails. Any retention held is released at the end of it. If you appoint us for ongoing maintenance, the handover record provides the starting point for that work.
Guide 01 · September 2026 · General guidance, not advice on a specific project.
Tell us about the building.
Send an address and a line about what you need. We aim to reply within one working day to discuss the next step and arrange a site visit where needed.