What detailed design (PZI) is and when you need it
Detailed design deepens main-project decisions to a buildable, procurable, controllable level. It is not the same document as the permit.
Detailed design is not decoration beside the permit. It is the layer for build, procurement, and site control.
Short answer
Detailed design is the construction layer. The main project (with the permit) approves what may be built. Detailed design clarifies how it is built: details, schedules, and discipline coordination at site level.
Why clients mix the terms
In conversation everything is "the project". In practice the levels differ. Concept sets direction. Main project carries the permit. Detailed design carries construction. Skipping a level costs more than extra drawing.
When it makes sense
A more complex building. More disciplines. Procurement that needs schedules. A contractor who will not improvise. An investor who wants fewer site surprises.
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What TENET does
We lead the detailed layer within written scope. We coordinate disciplines. We record decisions. We do not guarantee contractor behaviour. We do not replace site supervision unless contracted.
Read next
The main-project contents article. The building-permit process article. The detailed-design service page.
This text is informational and does not replace advice from a qualified professional for your specific case.
Questions around this topic
- A more detailed documentation layer for construction, procurement, and site control, after (or alongside) the approved main-project basis.
- Not automatically. It depends on complexity, the contractor contract, and how much detail you need to avoid expensive mistakes. We assess the case.