We start with your design. Modular is how we build it, not what you settle for.
Shape Homes · Where we build · Palo Alto
Palo Alto publishes two different maximum ADU sizes in two different places, and it has a tree provision that nobody else on the Peninsula has. Both are worth understanding before you draw anything.
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| Rule | What it says | Source |
|---|---|---|
| Maximum size | 900 sq ft, or 1,000 sq ft with two or more bedrooms | PAMC 18.09.040 |
| Conflicting figure | A second City source gives a different cap. Confirm with Planning | City ADU page |
| Height, detached | 16 ft, or 18 ft within half a mile of transit | PAMC 18.09.040 |
| Height, attached | 25 ft or the zone limit, whichever is lower. Two storeys | PAMC 18.09.040 |
| Setbacks | 4 ft side and rear. 3 ft minimum between ADU and house | PAMC 18.09.040 |
| Basement walls | No closer than 4 ft to an interior side or rear line | PAMC 18.09.040 |
| Parking | None required for an ADU | PAMC 18.09.040 |
| Privacy standards | Deck screens 5 ft 6 in, window sills 5 ft, lighting at 7 ft or below | PAMC 18.09.040 |
| Minimum tenancy | 30 days | PAMC 18.09.040 |
| Individual Review | Whether an ADU triggers Single Family IR is unconfirmed | City IR checklist |
Rows marked unverified were read from a secondary source, not from the Town's own published document. We do not build to an unverified number. Every figure here is confirmed against the Town before your drawings start.
Size is rarely the constraint. These are.
An ADU-only project that qualifies for state ministerial review, meaning 800 sq ft or under, may remove trees including protected trees without meeting the tree ordinance. Go over 800 sq ft and you drop onto the local pathway, where a protected tree comes out only under PAMC 8.10.050, and only where there is no other way to site the unit. That single threshold can be worth more than the extra 200 square feet.
A local-pathway project touching a TPZ needs an arborist-prepared preservation report. A state-pathway project needs only an applicant-completed disclosure. Protected trees may not lose more than 25% of functioning leaf, stem or root area in any 24-month period, which constrains where you can trench as much as where you can build.
PAMC 18.09.040 and the City's own ADU page do not agree on maximum size. We do not design to the more generous figure and hope. We confirm the current number with Planning at lot check and put the answer in writing.
Three from the library, chosen against this town's rules rather than its postcode.
Planning ranges, all in: factory package, delivery, foundation, utilities, permits and site work.
What moves a project inside its range is the lot, not the house. On Palo Alto parcels the items above are what usually decide it. A range is not a bid; a fixed price applies only as written in an executed construction agreement. See the plans or how the build works.
The municipal code gives 900 sq ft, or 1,000 sq ft for two or more bedrooms. A second City source gives a different figure. We confirm which governs your parcel with Planning before design, because the difference decides whether you are on the state or local pathway.
If the project is ADU-only and qualifies for state ministerial review at 800 sq ft or under, yes, including protected trees, without meeting the tree ordinance. Above 800 sq ft you are on the local pathway and removal of a protected tree needs an exception under PAMC 8.10.050.
No. Palo Alto requires no parking for an ADU. Two uncovered spaces apply if a single-family home is built at the same time, and covered parking is capped at 220 sq ft.
16 ft detached, or 18 ft within half a mile of transit. An attached unit may reach 25 ft or the underlying zone limit, whichever is lower, over a maximum of two storeys.
We pull your parcel, the Palo Alto ordinance and a street view of the driveway before the call.
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