Design and build, explained.

What design and build means

Design and build is a way of buying a building project. One company takes the contract for the design and the construction, so the drawings, the price and the work on site come from the same team. The alternative is the traditional route: you appoint an architect or a designer, they produce the drawings, the drawings go out to several builders for a price, and you sign a second contract with the builder you choose.

The difference sounds administrative. In practice it decides who is responsible when the drawing and the building disagree.

What changes for you

On the traditional route the designer and the builder are two companies with two contracts. If the built room does not match the drawing, each can point at the other. If the tender prices come back above the budget, the drawings go back to the designer and the clock starts again.

On a design and build contract there is one point of responsibility. The price is built from the drawings by the people who will build them, so a detail that is expensive or impractical is caught before it is priced rather than after it is half built. A change is drawn, priced and agreed before it is built. And the person who drew the room can be the person standing in it while it is built, which is how Lumina Designed runs a project.

What does not change

Design and build is a way of organising the work, not a shortcut around the rules. You still need planning permission where the work needs it, or a check that it falls under permitted development. You still need building regulations approval and the inspections that go with it. If the work touches a shared wall or comes near a neighbour's foundations, the Party Wall Act still applies. A good studio prepares one set of drawings that serves all three and builds the approval periods into the programme. The rules themselves are set out in planning permission versus building regulations and the Party Wall Act, in plain terms.

You also still sign off the design. On a well-run contract nothing is priced until you have approved the drawings and the finishes, and nothing is built until it is priced.

What to ask before you sign

• Who draws the room, and who prices it? The answer should be the same team. If the drawings are bought in and the price is guessed from them, the gap you were trying to close is still there.
• Is the price fixed against the drawings, and what is excluded? Ask for a priced schedule line by line. What is not in it should be written down as plainly as what is.
• What happens when something changes? The right answer is that it is drawn, priced and agreed before it is built, in that order.
• Who is on site day to day? A name, not a company. Ask whether that person saw the drawings before the price was written.
• What do I receive at handover? The as-built drawings and the finishes schedule, so a tile or a paint colour can be matched years later.
• Which approvals are included? Planning drawings, building regulations drawings, the party wall notices, the structural calculations. Each is either in the price or it is not.

Where the model works best

Design and build suits projects where the design and the build are close together: a restaurant fit-out with an opening date, a kitchen or bathroom where the finishes decide the first fix, a whole-house refurbishment, an extension or a loft where the structure and the finished room are drawn together. It is less useful when you already hold a complete set of drawings from another designer and want several prices for exactly that scheme, although even then a design and build studio will usually redraw the room before it prices it, so that its price is for something it has checked.

The studio's own version of the model is set out stage by stage on the process page: brief, drawings, price, build, keys, aftercare. The rooms it has produced are in the portfolio.