How to Become a Design and Build Company: A UK Guide for Builders

Most builders start the same way: an architect draws it, the client gets three quotes, and the cheapest builder wins. You price someone else's design, carry the risk of its gaps and fight over every variation.

Design and build turns that around. The client comes to you first, and you deliver the design and the building. You are no longer one of three quotes on the same drawings.

Craftex, the London company Sviat Jay runs, works as a design and build company. This guide covers how to become a design and build company: what changes, what you need in place and how to win the first projects. Want to plan the move with us? Book a free strategy call.

What design and build actually means

Under a traditional set-up, the client appoints a designer, then a builder to build what was drawn. Under design and build, the client appoints one company for both.

When design and build is right for your business

If you are not yet a main contractor, start with going from subcontractor to main contractor.

Step 1: Build your design team

You need design capability, not necessarily architects on your payroll.

• Architect or designer. Many firms start with one or two partner practices they appoint and manage.
• Structural engineer. Almost every extension, loft and structural refurbishment needs one.
• Specialists as needed: interior designer, M&E designer, party wall surveyor.
• Your own project manager who runs the design stage to a programme, with deadlines for client decisions.

Partner well and protect the relationship. Agree in writing how fees, responsibility and client contact work. Use non-solicitation terms so a partner cannot take your client direct. More in how to get work from architects and non-solicitation agreements in construction.

Step 2: Cover the design risk

When you take on design, you take on design liability.

• Professional indemnity insurance covers claims arising from design errors. Ask your broker what level your typical contracts need.
• Make sure your design partners carry their own cover and that your appointments with them pass responsibility down.
• Know your design duties. Anyone who prepares or modifies designs has duties under the CDM Regulations 2015 and the Building Regulations dutyholder rules. On many projects someone must be appointed principal designer. Check which roles you take on each job.

This is general information as of October 2026. Take advice from your broker and solicitor before you sign your first design and build contract.

Step 3: Use contracts written for design and build

A minor works contract assumes someone else did the design. Use a contract that matches what you are doing. That's the JCT Design and Build contract on larger or more formal projects, or a bespoke contract checked by a solicitor.

For private clients, Sviat advises bespoke contracts that strengthen the contractor's and design company's position. Compare the options in JCT Minor Works vs Intermediate vs Design and Build and JCT vs a bespoke contract for private clients.

The contract should state exactly what you design and what the client's requirements are. It should also say how design changes are priced and how long the client has to approve each stage.

Step 5: Sell one accountable service

Your pitch changes from "we build well" to "one company, one contract, one person responsible from first sketch to handover". Show it:

• A portfolio of finished projects with the design story: brief, design, build, result.
• A clear process page: stages, what the client gets at each one, what it costs, how long.
• A welcome pack with the programme and how decisions and variations work.
• Relationships that feed you projects early: estate agents, developers, past clients, interior designers.

Help making the move

The Main Contractor Accelerator is built for owners turning over £500K+ who want to become a design and build company or main contractor. It covers finding, pricing and tendering £100K–£1M+ projects, negotiation, a tender deck, cash flow, variations and delivery control.

Sviat Jay runs Craftex as a design and build company and mentors owners one-to-one himself, working from the strengths each owner already has.

The flagship is one-to-one, by application; smaller firms start in small groups (max 10–20) with regular one-to-ones. Built for results in about 4 months, not 1–3 years. Book a free strategy call to plan your move. Take the 4-minute Construction Business Scorecard to see if your systems are ready.