Design & Build versus architect-and-tender for a landed rebuild in Singapore.

The two routes, plainly

Architect-and-tender. You appoint an architect. They design the house with you, coordinate the structural engineer and other consultants, obtain planning approval, and prepare drawings and a bill of quantities. Several builders bid. You contract with the winner, and the architect administers the contract on your behalf, certifying payments and inspecting the work. Two contracts, two parties, one referee.

Design & Build. One firm holds one contract for both design and construction. Its architects design the house, its site team builds it, and each design decision is priced as it is made. One contract, one party, and the referee is the contract itself, together with the independent engineer who signs for the structure under either route.

Side by side

Question	Architect-and-tender	Design & Build
Who designs	Your appointed architect	The builder's in-house architects
When you know the number	After design is complete and tenders return, typically month 6 to 9	Progressively, as each drawing is priced; a fixed sum before approvals
Who carries design risk	You, through the architect; a buildability error becomes a variation	The builder; its drawings are its problem
Design fees	Typically 6 to 10 percent of construction value	Lower, bundled, because the firm recovers it in the build
Price discovery	Competitive tender	Negotiated, open-book if you insist on it
Change control	Architect instructs, builder prices, you pay	Priced in writing before it happens, or it does not happen
Structural check	Independent PE	Independent PE, the same requirement
Who inspects the builder	The architect	Your appointed PE on structure; you, or a clerk of works, on finishes
Best for	Design-led briefs, conservation, owners with a trusted architect	Budget certainty, attached houses, envelope-control rebuilds, programme

What each route costs

Appointing an architect costs 6 to 10 percent of construction value through to completion, with the structural engineer, QS and surveyors on top. That buys a design developed without a builder's commercial hand on it, and an administrator who certifies the builder's payments. It is money well spent on a complex brief.

Design & Build fees are lower because the firm recovers its design cost in the build, and the construction number is known months earlier. The risk is the opposite one: a builder designing to its own convenience. The defence is a detailed brief, a specification written into the contract with allowances per square metre, and the discipline of a firm whose work architects are willing to vouch for. The nine lines a quotation must show apply equally to both routes.

On headline price, a competitive tender for a fully developed design can come in lower than a negotiated Design & Build sum. Then the market does what it does: variation orders added mid-project run 15 to 30 percent of the original quotation, concentrated in the cheapest tenders, because the cheapest tender is the one with the most left out.

What each route takes

Architect-and-tender is sequential: design, then planning, then tender documents, then a tender period of four to eight weeks, then evaluation, then contract. Design & Build overlaps design and pricing and removes the tender period. On a landed house the difference is typically two to four months before a site start, which at S$12,000 to 13,000 a month in rent and interest is not a rounding error. On site, the routes converge: 14 to 24 months of construction depending on the house, the programme and the weather.

The engineer is independent under both

One misconception does a lot of damage: that Design & Build removes the independent check. It does not. Under either route a Qualified Person, almost always a Professional Engineer registered with the Professional Engineers Board, designs the structure, endorses the drawings, submits them to BCA, and supervises the structural works. The builder cannot sign for its own structure. CVC Engineers' complete guide to PE endorsement sets out what the engineer takes responsibility for, and their guide to BCA submission types explains the sequence of approvals that neither route can skip.

What Design & Build does change is who inspects finishes and programme on your behalf. Under tender, the architect does. Under Design & Build, you should expect weekly photo reports, named site management, and the right to appoint a clerk of works or your own PE for structural supervision. We build those into the contract rather than wait to be asked.

The question is not which route removes risk. It is which route puts the risk with the party best able to carry it.

When we would tell you not to choose us

• You already have an architect you trust. Keep them. Bring the drawings to us under Tender & Build, as GK Architects and design@LOFT have, or to anyone else. Do not give up a good design relationship for a procurement theory.
• Design ambition outranks budget certainty. A design competition, an architect with a signature, a house that is meant to be published: that is an architect-led project, and a Design & Build firm's commercial hand on the drawings would be the wrong instinct.
• Conservation or heritage. A conservation shophouse or a pre-war house needs specialist architects and a heritage impact process. Appoint them first.
• You want a referee. Some owners sleep better with an independent contract administrator certifying every payment. That is a legitimate preference, and it is what the architect-and-tender route is for.

When Design & Build is the right instrument

• You want to know the number before you demolish, and you want it to stay the number.
• The house is attached: a terrace or semi-detached rebuild where design, approvals, party-wall method and programme are one problem, not four. Our party-wall guide explains why.
• The rebuild is under URA envelope control, where design and approval cannot be separated without redrawing.
• You are paying rent, and two to four months matter.

Questions we are asked about procurement

Can I get a second opinion on a Design & Build price?

Yes, and you should. An independent quantity surveyor can benchmark the quotation against market rates in a week. We welcome it; a benchmarked number is a number nobody argues about later.

Can I switch routes midway?

From architect to Design & Build, yes: bring the developed design and we price it, keeping your architect for design intent if you wish. From Design & Build to tender, only before the construction contract is signed.

Who owns the drawings?

Ask under either route. Under our Design & Build contract you receive the full as-built set at CSC.