Design & Build

On the traditional route you appoint an architect to design the scheme, a structural engineer to calculate it, sometimes a quantity surveyor to cost it, and then send the drawings to three or four builders to tender. Each professional is contracted separately to you. It can produce excellent buildings, and it suits very large or unusual projects. It also has three well-known weaknesses for a domestic project: the design is often costed properly only after it is drawn, so budgets are discovered late; the builder inherits drawings they had no say in, so buildability problems surface on site as variations; and when something goes wrong, each party can point at the other.

Design and build removes those gaps. The people who will build the project help shape it while it is still on paper. Costs are tested at feasibility, before planning drawings are commissioned. Structural, drainage and services decisions are made with the site team, not discovered by them. And there is one contract, one programme and one person to call.

• Feasibility — a site visit, measured survey and options on paper with indicative costs and a planning view, so you choose a direction before paying for detailed design.
• Concept and developed design — plans, elevations and 3D views; kitchen, bathroom and joinery layouts; a finishes strategy that matches the budget.
• Planning and approvals — permitted development checks, householder or prior-approval applications, Lawful Development Certificates, and the council correspondence that goes with them.
• Technical design — Building Regulations drawings, structural engineer's calculations, drainage and services design, and a specification written in enough detail to price properly.
• Party wall and neighbours — advice on the Party Wall etc. Act 1996, notices, and liaison with surveyors where they are appointed.
• Construction — our own site team for structure, carpentry and finishing, with trusted specialist electricians, plumbers and roofers; a project manager on site; weekly updates.
• Completion — snagging, building control completion certificate, electrical and gas certificates, guarantees and manuals in one folder.

There is no separate "design and build fee". Design work is charged as a stage — feasibility, planning drawings, technical drawings — at a fixed price agreed in advance, and the construction is a fixed contract sum based on the finished specification. If you decide not to proceed to construction, you keep the drawings.

As a rule of thumb for 2026, design, engineering and approvals for a North London extension or renovation come to roughly 8–12% of the construction cost, including the council's application fees (a householder planning application in England costs £258 and a Lawful Development Certificate £129 from April 2025). The construction cost guides on each service page give realistic ranges for the build itself.

Stoyan Milkov, our director and project manager, is involved from the first site visit and manages the build. He trained in construction project management, and the company was founded by his father in 2010; that continuity is why our sites are orderly, our programmes are realistic and our clients tend to know exactly who is turning up on Monday.

Three habits define how we work. We price at feasibility so the design is never a fantasy. We write down every variation before it is built. And we finish — the snagging list, the paperwork, the return visit a year later — because a design and build company is only as good as the last 5% of the job.

See the full ten-stage process, or look at Northiam Road, a house we designed and built from a bare plot.

Good. We regularly price and build from other practices' drawings, and we are happy to work alongside your architect through construction. What we will do first is review the drawings for buildability and cost, and tell you plainly if something on paper is going to be expensive or awkward on site — before you have signed a contract, not after.