What the contractor is actually assessing
| What they look at | Why it moves your price |
|---|---|
| Site access | Whether equipment and materials can reach the build area — tight side yards can mean hand-carrying materials or craning, which costs real money. |
| Slope and drainage | Grading, retaining, and foundation design all scale with how far your lot is from flat. |
| Utility locations | The distance from your panel, water, sewer or septic to the ADU site drives trenching and connection costs — see our utility connections guide. |
| Electrical panel capacity | An older or full panel may need an upgrade before an ADU can be served. |
| Existing structures | For conversions: slab condition, ceiling height, framing. For new builds: what's in the way and what protecting it costs. |
| Trees, easements, and setbacks | Anything that constrains where and how big the buildable envelope actually is. |
What to have ready
Documents and information for walkthrough day
- Your goal, stated plainly — rental, family housing, office — because it changes design priorities and what the contractor recommends. Not sure of the type yet? Take our 60-second quiz first.
- A plot plan or survey if you have one — even the assessor-style parcel drawing helps; don't commission a new survey just for a walkthrough.
- Your rough budget range — contractors design to budgets; hiding yours usually produces a bid you can't use. Our cost guide shows typical SoCal ranges by type.
- Photos of problem areas — panel, cleanouts, crawlspace, anything you already know is odd about the property.
- Your timeline honestly — including anything that constrains it, like a family member's planned move-in.
- Anything the city told you — notes from a planning-counter conversation, or your city guide from our service area pages.
Questions worth asking while they're on-site
Ask every contractor the same list — comparable answers make comparable bids
- "What about this site concerns you?" — the honest ones name something; every site has something.
- "What would you build here and why?" — tests whether they're designing for your lot or reciting a package.
- "What's NOT included in your bid?" — exclusions are where budgets die; our bid-comparison guide covers the common ones.
- "Who runs my job day to day, and how many projects do they carry?"
- "What similar projects have you completed nearby?" — then actually check the references. Our red-flags checklist covers what to verify.
- "How do you handle changes once we've started?" — you want a written change-order process, not "we'll work it out."
After the walkthrough
Expect a written proposal, not a number quoted from the driveway. When bids arrive, compare scope line by line before comparing totals — a lower number that excludes utility trenching isn't lower. Walk through our bid-comparison guide with all proposals in hand, and treat pressure to sign on the spot as the red flag it is.
Frequently asked questions
Not necessarily. Many homeowners walk contractors first — especially design-build firms who produce plans in-house. If you already have plans, bring them; if not, the walkthrough helps decide between the architect and design-build paths. See our architect vs. design-build guide.
Two or three produces comparable bids without walkthrough fatigue. More than that and the bids stop being better — they just take longer to collect.
Yes, as a range. A contractor designing blind either over-designs past your budget or under-designs below your goals. The budget conversation you're avoiding at the walkthrough happens anyway — later, expensively.