Picture a project that started as a fixed price. A fixed-price contract, a fully resolved design, a clear timeline. That was the plan. It’s a plan we’ve seen play out many times.
Months on, the contract value has moved well beyond where it started. A drift in the order of 15 to 20% on a project everyone agreed was locked in at the outset. That kind of movement isn’t rare on complex architectural work.
When it happens, it’s usually fully documented every step of the way. It isn’t about client whims or scope changes for the sake of it. It’s the slow evolution of a design that wasn’t actually as resolved as everyone assumed.
This is what I've started calling the developed design trap. And it's worth talking about openly, because clients don't always know it exists, and the language we use across the industry doesn't always help them see it coming.
How the trap works
The setup is familiar.
A client engages an architect. The architect designs the home. By the time the documentation is ready for pricing, the client assumes two things:
The design is resolved.
The cost will be locked in.
The architect runs a fixed-price tender. Three or four builders price the same documentation and compete on price. The client picks one, signs a fixed-price contract, and feels confident they've made the best decision at the best price.
What never gets discussed openly is contingency. Not really. Not in a way that names what kind of risk sits where.
The contingency that does get talked about tends to sit in two places: the design that isn’t fully resolved, and the unknowns that come with consenting, underground services, and the things you simply can’t see until you start.
On a complex architectural home, that's most of the project.
What actually happens on site
Architecturally led work is often groundbreaking and being done for the first time, ever. That means some of the design isn’t fully resolved at tender. And because of that, some things get figured out once you're on site. Existing conditions in a renovation. A neighbour's boundary. Council requirements.
These become design changes during construction. On a busy month, that can mean a steady run of change events, sometimes close to one a day.
"Can you price this change? Can you price this change? Can you price this change?"
Each one needs assessing, costing, communication, sign-off. Work happens out of sequence. The team has to keep pausing, regrouping, and adjusting. Hard landscaping that was meant to be done in one continuous push gets broken up over months. Trades need to come back.
The cost stacks up. The timeline stretches. And from the outside, it looks like a budget blowout.
Why the trap is worth naming
When costs drift on a complex build, the story usually gets simplified.
From the outside, sometimes it looks like a budget blowout. The builder went over. That may be the headline you’ve heard at dinner parties or in the news.
What that version misses is everything that happened upstream. The design that kept evolving. The detail that needed resolving. The site condition no one could have known about. The variation that came through in week six and changed the sequence of works for the next three months.
None of that is unique to one project or one team. It's the nature of architectural work. Complex builds carry uncertainty. It's reality.
But when no one names the uncertainty openly at the start, the simplified story is the one that sticks at the end. And that's bad for everyone around the table. It's bad for the client, who feels misled. It's bad for the architect, whose project becomes the cautionary tale. And it's bad for the builder, who ends up carrying reputational damage.
The fix isn't blame. The fix is language.
What clients and architects can do
The trap isn't anyone's individual fault. It's a systemic dynamic the industry has created. For clients building architectural homes, there are a few practical things worth understanding.
Fixed price is only as fixed as the design is resolved.
If the documentation is still evolving when you sign, your contract sum will evolve with it.
Ask about contingency, and ask whose it is.
Some risk belongs to the owner and some belong to the builder. This is part of the two conversations every architectural build needs.
A tender between competing builders doesn't guarantee certainty.
It guarantees a price for what's been documented. The unresolved parts aren't priced, because they can't be.
As an industry, we need to continue to work on our shared language.
We talk about fixed price. We talk about variations. We rarely talk about owner contingency versus builder contingency, or developed design risk, or what "fully resolved" actually means in practice.
The goal across the industry should be clarity for all parties around the table. So the discussion, the wording, and the contract reflect what everyone actually intended.
Naming the developed design trap is one part of that.
