Design and Build means one company takes responsibility for your project from the first sketch to the final coat of paint, rather than you managing separate architects, engineers and contractors yourself. For homeowners in London juggling planning permission, structural design and construction across a single project, it removes the single biggest source of delay and disagreement: who is actually responsible when something needs to change.

At a glance

  • What is included: design, planning applications, structural engineering, construction and finishing under one contract
  • Single point of responsibility: one company accountable for design, cost and programme, rather than three separate parties
  • Best suited to: extensions, loft conversions, basement conversions and full refurbishments where design and build need to be coordinated closely
  • Pricing: fixed against an agreed design and specification, established before construction begins

Design and Build versus the traditional route

In the traditional route, you appoint an architect to design your project, then separately tender the construction to a builder once drawings are complete. If the builder’s price comes in over budget, or if a detail proves difficult to build once work starts, the architect and the builder can end up pointing at each other while your project stalls and you sit in the middle.

Under Design and Build, the same company that designs your project also prices and builds it. This means design decisions are made with a realistic understanding of cost and buildability from day one, and there is nobody else to blame when a decision needs revisiting, because the responsibility for the whole outcome sits in one place.

What our Design and Build service includes

Design and feasibility

We start with a site visit to understand what is possible on your property, followed by initial design options that respect your budget as well as your ambitions. This stage also flags any planning constraints, such as conservation area status or Article 4 restrictions, before you commit further.

Planning and Building Regulations

Where full planning permission is needed, we prepare and submit the application on your behalf. Every project also requires Building Regulations approval, and we handle the drawings, calculations and inspections required to achieve sign-off.

Structural engineering

Steel beams, underpinning, floor lowering and other structural elements are designed by a qualified structural engineer as part of our service, with calculations submitted to Building Control alongside the architectural drawings.

Construction and project management

One dedicated site manager oversees the build from groundworks through to final decoration, coordinating our in-house trades, so you are dealing with one person throughout rather than a rotating cast of subcontractors.

Why a fixed price matters

Because design and construction sit within one contract, we can commit to a genuinely fixed price against your agreed specification before work begins, rather than the estimate creeping upward once foundations are dug and the scope is discovered to be larger than assumed. Every material and labour cost is itemised in your quote, so you know exactly what you are paying for and what would trigger a change.

Why choose Alpha London Builders for Design and Build

We combine our own design and technical team with in-house tradespeople, so the handover between design and construction that causes delays on split-contract projects simply does not exist on ours. From your first survey to final handover, you deal with the same team and the same fixed price. Browse our completed projects to see the range of extensions, loft conversions and refurbishments delivered this way.

Frequently asked questions

Is Design and Build more expensive than hiring an architect separately

Not typically. Because design decisions are made with real construction costs in mind from the outset, Design and Build often avoids the redesign and re-tender cycles that add cost and time under the traditional route.

Do I lose creative control over the design

No. You review and approve every design stage before it proceeds, exactly as you would with an independent architect, with the added benefit that your builder is involved early enough to flag buildability issues before they become expensive surprises.

What types of project suit Design and Build

Extensions, loft conversions, basement conversions and full property refurbishments all benefit from having design and construction managed as one process, since these projects typically involve the most coordination between design decisions and structural reality.

Can you take over a project an architect has already designed

Yes. We regularly price and build from independently prepared drawings, and will flag any buildability or cost concerns with those designs during our quotation process.

Book a design consultation and find out what a single-team approach could do for your project.