Guide
What homeowners need to know.
Short Answer
Bay Area cost per square foot is a blunt tool. It can help with early sanity checks, but it should not replace scoped estimates, drawings, and allowance details.
Why Numbers Vary
A kitchen remodel, garage conversion, detached ADU, second-story addition, and custom home do not share the same cost structure. Site work, utilities, engineering, finishes, and permits make the spread wide.
How to Use It
Use cost per square foot to reject fantasy budgets, then move into scope-based estimating. If someone gives one clean number without assumptions, ask what is missing.
Cost table
Use ranges until scope is real.
| Item | Planning range | Why it moves |
|---|---|---|
| Remodel | Highly variable | More useful when broken down by room and scope. |
| Addition | Scope-based | Foundation, structure, roof, and utility tie-ins matter. |
| ADU | Type-based | Garage conversion and detached ADU numbers should not be compared directly. |
Mistakes
Avoid these expensive shortcuts.
- Comparing numbers that include different scopes
- Ignoring soft costs
- Treating cost per square foot like a contract number
FAQ
Fast answers.
Is cost per square foot useless?
No. It is useful for early screening. It becomes dangerous when treated like a scoped estimate.
What should a cost range include?
It should state whether design, permits, engineering, site work, utilities, finishes, allowances, and contingencies are included.
Why do contractors give different numbers?
They may be pricing different scopes, assumptions, risk, staffing, schedule, overhead, or quality levels.