Design-build vs design-bid-build is a choice about who owns the gaps. In design-bid-build, the owner hires a designer, finishes the drawings, then tenders them to a separate builder, and every problem on site has two possible owners. In design-build, one team carries design and construction together, so “that’s not in my scope” has nobody to point at. UNFORMALDESIGN is a Bangkok-based interior design and architecture studio, led by Italian architect Alessio Carta, that designs restaurants, bars, beach clubs and hotels across Thailand and runs projects from concept to opening day. This article compares the two routes and lists the places where scope gaps usually open on a hospitality fit-out.
Design-build vs design-bid-build: what is the difference?
Design-bid-build is the traditional route: design first, then a tender, then construction, with two separate contracts held by the owner. Design-build is a single contract in which one entity is responsible for both the design and the construction. Turnkey interior design is the interiors version of design-build: the owner receives a finished space ready to operate.
| Design-bid-build | Design-build / turnkey | |
|---|---|---|
| Contracts the owner signs | two: designer and contractor | one |
| When the builder joins | after the drawings are finished | from the concept stage |
| Who resolves a detail that fails on site | negotiated between designer and contractor | the same team that drew it |
| Material substitutions | proposed by the contractor, approved or argued by the designer | decided inside the team against the approved design |
| Price certainty | a tender price on finished drawings, then change orders | a target agreed earlier, refined as design develops |
| Main risk for the owner | gaps between the two contracts | choosing the wrong single team |
Design-bid-build is not a bad route. It suits owners with an in-house project manager who can referee between designer and builder, and projects where public tender rules require it. On a restaurant or hotel fit-out with a fixed opening date and no project manager on the owner’s side, the referee job usually falls to the owner by default.
What does the research say about the two delivery methods?
The largest recent comparison is “Revisiting Project Delivery Performance 1998 to 2018”, a study by the Construction Industry Institute and the Charles Pankow Foundation that analysed 212 completed projects. Compared with design-bid-build, design-build projects showed 3.8 percent less cost growth, 1.7 percent less schedule growth, 36 percent faster construction and 102 percent faster delivery from design to completion.
Two limits matter when reading those numbers. The projects were mostly buildings in the United States, not interior fit-outs in Thailand, and the study was published with the support of the Design-Build Institute of America, which promotes the method. The direction is still useful: most of the time saved comes from overlapping design and construction instead of running them in sequence, and that overlap is exactly what a hospitality owner needs when rent starts before the doors open.
Where do scope gaps open on a restaurant or hotel fit-out?
A scope gap is any task that both the designer’s contract and the builder’s contract can reasonably say belongs to the other. On hospitality projects the same eight items cause most of the arguments, and each one is cheap to assign on paper and expensive to discover on site.
| Item | Why it falls between the two | What it costs when nobody owns it |
|---|---|---|
| Joinery shop drawings | the designer draws intent, the workshop draws production | a bar counter built to the wrong height or depth |
| Air conditioning and extraction | ducts are sized by engineers, ceilings by the designer | lower ceilings than drawn, or visible ducts in the dining room |
| Lighting fixtures and dimming | fixtures are specified, drivers and controls are not | a room that looks right at noon and wrong at 8 PM |
| Material substitutions | “or equal” clauses invite cheaper alternatives | a finish that photographs well and wears out in a year |
| Loose furniture and decor | often outside both contracts | chairs ordered late, opening without them |
| Signage and graphics | branding agency, designer and builder all touch it | power and fixings missing where the sign goes |
| Kitchen and bar equipment interfaces | supplied by a third vendor | drainage, gas or power in the wrong place |
| Snagging before opening | the builder closes, the designer has left site | defects found by the first guests |
In Thailand two more items deserve a line in the scope. Structural or facade changes need a permit under the Building Control Act B.E. 2522 (1979), so someone has to own the application and the drawings behind it. In a mall or a hotel complex, the landlord’s fit-out approval and working hours shape the programme, and someone has to own those meetings too.
How UNFORMALDESIGN runs a turnkey project
UNFORMALDESIGN keeps one team responsible for the result across four stages: concept, drawings, construction follow-up and delivery, from the first sketch to the day the doors open. Alessio Carta’s line on it is short: that is how the room the client approved becomes the room the client gets.
The portfolio shows what that chain covers in practice: Ombra and AILATI in Bangkok, Warehouse Wine & Dine, a 1,000 square metre restaurant in Phuket, and Socialtel on Koh Samui, a rebrand and redesign of an existing building into a beach club that works by day and by night. On Koh Samui and in Phuket the early phases run remotely, with site visits at key milestones and during construction, which is where a single responsible team matters most: the person who drew the detail is the person who answers for it on site.
The studio’s material system approach helps with the substitution problem in particular. Pallets, PVC crates, oil barrels and glass bottles, used as modular architectural elements, are procurable in Thailand without long import lead times, so a material is less likely to be swapped late because it did not arrive.
What this article does not cover
This article compares delivery methods for interior fit-outs. It does not cover construction contract law, retention percentages or insurance, which depend on the specific contract and should be reviewed by a lawyer. Google Ads Keyword Planner data pulled on 5 October 2026 shows about 1,600 monthly searches worldwide for “design build vs design bid build”, 1,900 for “design and build contract” and 720 for “turnkey interior design”, with about 30 a month for the last one in Thailand.
Working with UNFORMALDESIGN
For restaurants, bars, beach clubs and hotels in Bangkok, on Koh Samui, in Phuket and elsewhere in Thailand, the first conversation is the right time to decide who owns each line in the scope table above. Contact UNFORMALDESIGN at alessio@unformaldesign.com or on WhatsApp at +66 97 112 3561.
Frequently Asked Questions
What is the difference between design-build and design-bid-build? In design-bid-build, the owner hires a designer, completes the drawings and then tenders them to a separate contractor, so there are two contracts. In design-build, one entity is responsible for both design and construction under a single contract. Turnkey interior design is the interiors version of design-build, delivering a space ready to operate.
Is design-build faster than design-bid-build? In most studies, yes. A Construction Industry Institute and Charles Pankow Foundation study of 212 projects found design-build was 36 percent faster in construction and 102 percent faster from design to completion than design-bid-build. Most of the gain comes from overlapping design and construction instead of running them one after the other.
What does turnkey interior design include? Turnkey interior design usually covers concept, design development, technical drawings, coordination with engineers and suppliers, construction follow-up on site and handover of a finished space. Loose furniture, signage and kitchen equipment should be listed explicitly in the scope, because these are the items most often left between contracts.
When is design-bid-build the better choice? Design-bid-build suits owners who have their own project manager to coordinate designer and contractor, projects that must follow public tender rules, and projects where the owner wants to compare several builders on identical finished drawings. Without that coordination on the owner’s side, the owner ends up refereeing every gap.
Does UNFORMALDESIGN offer turnkey interior design on Koh Samui and in Phuket? Yes. UNFORMALDESIGN is based in Bangkok and runs hospitality projects across Thailand, including Socialtel on Koh Samui and Warehouse Wine & Dine in Phuket, with one team responsible from concept and drawings through construction follow-up to opening day. Early phases run remotely, with site visits at key milestones.
The takeaway
Design-build vs design-bid-build comes down to who referees the gaps. On a restaurant or hotel fit-out with a fixed opening date, UNFORMALDESIGN keeps concept, drawings, construction follow-up and delivery under one team, so the room the owner approves is the room the owner gets.
Internal links: /interior-design-koh-samui/ (interior design on Koh Samui) · /hospitality-interior-design-thailand/ (hospitality interior design in Thailand) · /interior-design-phuket/ (interior design in Phuket) · /projects/ (projects)