Can you build an ADU in Danville? (94506)

What the parcel data shows in Danville

We ran every single-family parcel in 94506 — 7,247 of them — through the same eligibility engine behind our address checker: real parcel geometry, a 4-foot setback inset, existing building footprints subtracted, then CAL FIRE and FEMA hazard layers applied. 94.6% can fit a detached ADU. That puts Danville in the top quarter of everywhere we have analyzed — it is an unusually workable neighborhood for a backyard home.

Underneath that headline: 48.3% of lots come back clearly eligible, 46.3% are eligible with a caveat we would want to confirm, and 5.4% need a closer look before anyone should rely on an answer. The last group is not a rejection — it is where the public data runs out and a person has to look.

How much room is actually left

The median lot in Danville is 9,219 square feet, but lot size is not buildable size. After setbacks and the footprint of the existing home, the median parcel here has 5,597 square feet of genuinely usable rear-yard area — roughly 39% of the lot is spoken for before you start.

Of the lots we analyzed, 95% have room for at least a compact detached unit, and 71.5% can take a full two-bedroom-plus home. The most commonly recommended size in Danville is the EVO Two Plus, which is the best fit on 71.5% of lots.

Because most parcels here clear the bar for a larger unit, the binding constraint in Danville is usually preference and budget rather than geometry.

What holds lots back in Danville

49.3% of lots in 94506 sit inside a CAL FIRE fire hazard severity zone. Those lots trigger CBC Chapter 7A wildland-urban interface construction requirements, which raise the cost of the exterior envelope. Lots outside the zone are unaffected.

What an ADU could earn in Danville

HUD puts the fair market rent for a one-bedroom in 94506 at $3,070 a month, while Zillow's observed index for the same ZIP — all home sizes — sits at $5,147. The first is a conservative, bedroom-specific 40th-percentile figure; the second is a broader market signal. A detached ADU here would realistically rent somewhere between the two, depending on size and finish.

Rent is only half of the return. The other half is what the project costs on your particular lot — the unit price is fixed, but site work, utility runs and permits move with the parcel. Those are the numbers worth pinning down before you decide.

Why your lot may differ from these numbers

Everything above is a neighborhood aggregate across 7,247 parcels in Bay Area. It is a good guide to what is normal on your street and a poor guide to your specific property. Two adjacent lots of identical size can reach opposite conclusions — one has a shallow house and a wide side yard, the other a detached garage sitting exactly where a unit would go.

The analysis also works from public records. It does not know your soil, your utility routing, your easements, or anything a survey would reveal. Run your own address for a parcel-specific answer, and treat both as a screen rather than a permit determination.

Common questions about ADUs in Danville

Can you build an ADU in Danville (94506)?

Yes. Of the 7,247 single-family lots we analyzed in 94506, 94.6% can fit a detached ADU under California state law — 48.3% clearly eligible and 46.3% eligible with a caveat to confirm. The median lot has 5,597 square feet of buildable area left after setbacks and existing structures.

How big of an ADU fits on a typical Danville lot?

95% of lots in 94506 fit at least a compact detached unit and 71.5% fit a full two-bedroom-plus model. The most commonly recommended size here is the EVO Two Plus, best fit on 71.5% of lots. Your own maximum depends on setbacks, the position of your existing home, and access.

What is the average lot size in 94506?

The median single-family lot in 94506 is 9,219 square feet. More useful for an ADU is the buildable remainder: after a 4-foot setback inset and subtracting the existing home's footprint, the median parcel retains 5,597 square feet of usable rear-yard area.

Is Danville in a fire hazard zone?

49.3% of lots in 94506 fall inside a CAL FIRE fire hazard severity zone. Building there triggers CBC Chapter 7A wildland-urban interface requirements — fire-rated exterior materials, ember-resistant vents and restricted decking — which add cost the state ADU statute does not mention. Whether your specific parcel is affected depends on its exact location.

How much rent could an ADU earn in Danville?

HUD's fair market rent for a one-bedroom in 94506 is $3,070 a month, and Zillow's all-sizes observed index for the ZIP is $5,147. Actual rent depends on unit size, finish, parking and privacy — treat these as an area expectation rather than a quote for your unit.

Is Danville a good neighborhood for an ADU?

On the physical measures we can check, Danville ranks higher than 93% of the neighborhoods in our data, with 94.6% of lots able to fit a detached unit. That reflects lot geometry and hazard exposure only — not demand, rent growth, or local permitting speed, which vary independently.