Module 11 · Lesson 3
The Structural Engineer: Your Quietest Critical Hire
You'll rarely hire the structural engineer directly — but you should verify three things about whoever stamps your ADU's structure.
You already know what structural engineers do (lesson 9.3). This short lesson covers the hiring reality — which is that you usually don't hire them directly, and the three things to verify anyway.
How the hire usually works. Your designer brings their engineer — a standing partnership where the two have resolved the glass-vs-shear-wall dance dozens of times (lesson 9.7). Design-build firms have them in-house or on permanent call. This is good: the relationship is what you're buying, and a designer-engineer pair with history coordinates sets that sail through plan check. You'll typically see the engineering as a line item ($3K–$8K+, Module 6.5) passed through your design contract.
When you'd hire directly: owner-builders assembling their own team; conversions needing only an engineer's evaluation (is this garage foundation adequate? — a smart early spend from Module 3); or projects where a city demands supplemental calculations.
The three things to verify, whoever brings them:
- License. California structural work requires a licensed Civil or Structural Engineer (PE/SE). Verify at the state licensing board's website in thirty seconds. The stamp on your plans is a legal instrument — know whose it is.
- Residential experience in your conditions. An engineer who mostly does commercial tilt-ups approaches a backyard ADU differently than one who's detailed a hundred of them. Hillside project? Ask specifically about hillside residential work.
- Responsiveness reputation. Correction letters (Module 10) routinely include structural items, and a slow engineer stalls the whole response matrix. Ask your designer honestly: does this engineer turn corrections in days or weeks?
One planning tip worth repeating from Module 3: for garage conversions and above-garage dreams, a few hundred dollars of engineer's site evaluation before design begins converts the biggest cost unknowns (foundation condition, structural capacity) into known numbers. It's the cheapest de-risking move in the entire project.
Key takeaways
- You usually get the engineer through your designer — and the partnership is the value.
- Verify three things: state license, residential experience in your conditions, correction-response speed.
- Owner-builders and evaluation-only jobs are the direct-hire cases.
- A pre-design structural evaluation of an existing garage is the cheapest de-risking money in the project.