By Eric Sun · CSLB #1146788 · Updated
Short answer
On lots up to about 10,000 sq ft, Palo Alto allows the most floor area (0.45 of the first 5,000 sq ft, 0.30 after) and 30 ft height [1]. Los Altos R1-10 allows 35% of the lot and 27 ft [4]. Menlo Park allows 2,800 sq ft plus 25% of lot area over 7,000 sq ft, and 28 ft [7].
Which zone you are probably in
Each city splits single-family land into several districts, and the numbers below depend on which one your parcel sits in. Palo Alto has one R-1 district plus four lot-size subdistricts, R-1(7,000), R-1(8,000), R-1(10,000) and R-1(20,000), and a single-story (S) overlay [1]. Los Altos's main single-family district is R1-10, with R1-H, R1-20 and R1-40 covered in their own chapters [4]. Menlo Park has R-1-U (7,000 sq ft minimum lot) and R-1-S (10,000 sq ft minimum lot), along with R-E, R-E-S, R-1-S (Felton Gables) and R-1-U (Lorelei Manor), which follow different rules [7],[8]. This guide compares Palo Alto R-1, Los Altos R1-10 and Menlo Park R-1-U/R-1-S. Check the city's zoning map for your parcel before you rely on any figure.
Side-by-side comparison
| Rule | Palo Alto | Los Altos | Menlo Park |
|---|---|---|---|
| Zone compared | R-1 and subdistricts [1] | R1-10 [4] | R-1-U and R-1-S [7],[8] |
| Max floor area | 0.45 x first 5,000 sq ft of lot + 0.30 x lot area over 5,000; 6,000 sq ft max house size [1] | Lots up to 11,000 sq ft: 35% of net lot area; larger lots: 3,850 sq ft + 10% of area over 11,000 [4] | Lots 5,000-7,000 sq ft: 2,800 sq ft; larger lots: 2,800 + 25% of area over 7,000; second floor max 50% of the limit [7],[8] |
| Lot coverage | Two or more stories: 35%, plus 5% for patio or overhang; single story: up to the allowed floor area [1] | 35% where a one-story building stays at or under 20 ft; two-story homes not allowed if coverage exceeds 30% [4] | Two or more stories: 35%; single story: 40% at 7,000 sq ft or less, sliding to 35% at 10,500 sq ft [7],[8] |
| Max height | 30 ft to the roof peak; 33 ft with a 12:12 or steeper roof; 17 ft and one habitable floor in the (S) overlay [1] | 27 ft and two stories; 20 ft if coverage exceeds 30%; flag lots one story and 20 ft [4] | 28 ft on lots under 20,000 sq ft; 30 ft on lots of 20,000 sq ft or more [7],[8] |
| Daylight plane | Side: starts 10 ft high at the interior side lot line, 45 degrees; rear: 16 ft at the rear setback line, 60 degrees [1] | Lots 70 ft or wider: 11 ft at each side property line, 25 degrees; narrower lots: 19 ft at the second-story setback line, 25 degrees [4] | At the side setback line: 12'6" for single-story, 19'6" for two-story, then 45 degrees inward [9] |
| Front setback | Contextual: 20 ft, or the block average if that average is 30 ft or more [1] | 25 ft [4] | 20 ft [7],[8] |
| Side setbacks | Interior: 6 ft in R-1, 8 ft in the subdistricts; street side: 16 ft [1] | Interior: 10 ft first story, 17.5 ft second story; exterior side: 20 ft; narrow lots use a percentage formula [4] | R-1-U: 10% of minimum lot width, 5 ft min and 10 ft max; R-1-S: 10 ft; corner street side: 12 ft [7],[8] |
| Rear setback | 20 ft [1] | 25 ft; lots under 100 ft deep: 25% of depth or 20 ft, whichever is greater [4] | 20 ft [7],[8] |
| Basement counted in floor area? | No, if it is not habitable, or if the first floor is no more than 3 ft above grade; it may not extend beyond the building footprint [2] | No, basements are excluded from gross floor area, but the space must meet the strict "basement" definition [5],[4] | No, if the main floor above is 30 inches or less above grade [10] |
| Design review trigger | New two-story home, new second story, or second-story expansion over 150 sq ft that does not meet the objective two-story standards: Individual Review [1],[3] | Every new house: administrative review if one story under 20 ft; zoning administrator review at a public meeting if two-story or over 20 ft [6] | Use permit when building two or more stories on a lot below the district minimum width, depth or area, or any home on a lot under 5,000 sq ft [11] |
Palo Alto R-1: the most floor area, the most process for two-story designs
Palo Alto's gross floor area includes garages and carports, and volume over 17 ft tall counts twice, so a double-height living room spends your FAR quickly [1]. The 35% coverage cap applies only to multi-story homes. A single-story house may cover as much of the lot as its allowed floor area, which makes a large one-story plan easier to fit here than in the other two cities [1]. Two code features hold houses back. The daylight plane starts just 10 ft up at the side lot line [1]. And two-story work must either meet the City Council's objective two-story standards or go through Individual Review [1],[3]. Lots in the (S) overlay are limited to 17 ft and one habitable floor [1]. Substandard lots (less than 50 ft wide or 83 ft deep, and under 83% of the minimum area) have the same 17 ft, one-floor limit [1].
Basements are where Palo Alto projects gain the most space. A basement stays out of gross floor area as long as the first floor is no more than 3 ft above grade, but it may not reach beyond the footprint of the house or sit under any part that encroaches into a setback. Basements are not allowed in special flood hazard areas [2]. Lightwells must stay out of the front and are capped at 3 ft wide, and they may total no more than 30% of the basement perimeter [2].
Los Altos R1-10: generous setbacks, a gentle daylight plane, and design review for every new house
Los Altos's 35% FAR looks simple, but its other rules shape the house more. Two-story homes are not allowed once lot coverage exceeds 30%, and a home over 30% coverage is also capped at 20 ft tall [4]. You choose between a sprawling single-story plan and a compact two-story one. The second story must sit 17.5 ft from interior side lines, against 10 ft for the first story [4]. On lots 70 ft or wider, the daylight plane starts at 11 ft and rises at only 25 degrees, which pushes second floors toward the middle of the lot [4]. Flag lots are limited to one story and 20 ft [4]. Lots narrower than 80 ft, or 90 ft on a corner, use percentage-based side yards instead of the fixed 10 ft [4].
Basements are excluded from gross floor area [5], but the code defines a basement narrowly. It must be wholly below finished grade on all sides, and lightwells may break no more than 20% of the exterior wall length, with each lightwell no wider than 4 ft [5]. Basements cannot extend beyond the first floor above them, and lightwells are not allowed in the front or exterior side setback [4]. Under the design review chapter adopted in 2025, a new one-story house under 20 ft gets administrative review. A new two-story house, or a one-to-two-story conversion, goes to the Zoning Administrator at a noticed public meeting [6].
Menlo Park R-1-U / R-1-S: a fixed base plus a sliding scale, with a second-floor cap
Menlo Park's floor area limit (FAL) uses the same formula in R-1-U and R-1-S: 2,800 sq ft for lots of 5,000 to 7,000 sq ft, plus 25% of any lot area above 7,000 sq ft [7],[8]. The second floor may hold no more than 50% of the total. On lots more than twice as long as they are wide, the second-floor cap is the greater of 1,400 sq ft or a width-to-length formula [7]. Floor area counts garages. Single-story rooms 17 ft or taller count at 200%. In two-story homes, rooms with ceilings over 12 ft count at 200% and attic space 5 ft or taller counts too [10]. Single-story homes get the more generous coverage (up to 40% on smaller lots) and a lower daylight plane start of 12'6". Two-story homes are held to 35% coverage with the plane starting at 19'6" [7],[9].
The big Menlo Park variable is lot size against the district minimum. R-1-S requires 10,000 sq ft and 80 ft of width; R-1-U requires 7,000 sq ft and 65 ft [8],[7]. A lot that falls short of its district's width, depth or area is substandard for two-story purposes, and building two or more stories on it requires a use permit from the Planning Commission [11]. Separately, a remodel that expands an existing structure by more than 50% of its existing floor area limit is treated as a new structure [10]. Basements under a main floor no more than 30 inches above grade are excluded from floor area [10].
Worked example: maximum floor area on a 7,500 and a 10,000 sq ft lot
Using each city's published formula, and assuming a flat, interior, non-flag lot with no overlay. Palo Alto R-1, 7,500 sq ft: 5,000 x 0.45 = 2,250, plus 2,500 x 0.30 = 750, for 3,000 sq ft [1]. Los Altos R1-10, 7,500 sq ft: 7,500 x 0.35 = 2,625 sq ft [4]. That lot is below the 10,000 sq ft R1-10 minimum, but the FAR formula still applies [4]. Menlo Park R-1-U, 7,500 sq ft: 2,800 + 0.25 x 500 = 2,925 sq ft, of which about 1,462 sq ft at most may be on the second floor [7]. On a 10,000 sq ft lot the results are 3,750 sq ft in Palo Alto [1], 3,500 sq ft in Los Altos [4] and 3,550 sq ft in Menlo Park [7],[12]. Footprint limits differ more than floor area. At 7,500 sq ft, a two-story home may cover 35%, or 2,625 sq ft, in Palo Alto and Menlo Park [1],[7], and Palo Alto allows another 5% for a patio or overhang [1]. In Los Altos a two-story design must stay at or under 30% coverage, which is 2,250 sq ft [4].
| Lot size | Palo Alto R-1 | Los Altos R1-10 | Menlo Park R-1-U / R-1-S |
|---|---|---|---|
| 7,500 | 3,000 [1] | 2,625 [4] | 2,925 [7] |
| 10,000 | 3,750 [1] | 3,500 [4] | 3,550 [8],[12] |
These are ceilings, not targets. Garages count toward floor area in Palo Alto and Menlo Park, and toward gross floor area in Los Altos, so a two-car garage of roughly 400 sq ft comes out of the totals above [1],[5],[10]. A basement that meets each city's rules adds space on top of them [2],[5],[10].
Code checked 2026-10-02 against each city's official online municipal code. Overlays (Palo Alto's single-story S overlay, flood zones, special setback maps), flag and substandard lots, recorded deed restrictions or HOA rules, historic status, and SB 9 two-unit projects can each change these results. Before you buy or design, get a parcel-specific check. Blue Lion Builder offers a free feasibility assessment for homes in Palo Alto, Los Altos and Menlo Park.
Common questions
- What is the FAR in Los Altos?
- In the R1-10 district, maximum floor area is 35% of net lot area for lots up to 11,000 sq ft. Larger lots get 3,850 sq ft plus 10% of the area above 11,000 sq ft [4]. Other single-family districts (R1-H, R1-20, R1-40) have their own chapters [4].
- How is FAR calculated in Palo Alto?
- In the R-1 district and its subdistricts, multiply the first 5,000 sq ft of lot area by 0.45 and the remainder by 0.30. Total house size is capped at 6,000 sq ft. Garages count, and volume over 17 ft tall counts twice [1].
- Do basements count toward floor area in Palo Alto?
- Generally no. A basement is excluded if it is not habitable, or if it is habitable and the first floor is no more than 3 ft above grade. It cannot extend beyond the building footprint, and lightwells must meet size and location limits [2].
- What is the floor area limit in Menlo Park?
- In R-1-U and R-1-S it is 2,800 sq ft for lots of 5,000 to 7,000 sq ft, plus 25% of lot area over 7,000 sq ft. Lots under 5,000 sq ft need a use permit to set the limit. The second floor may be no more than 50% of the total [7],[8].
- How tall can a house be in Palo Alto, Los Altos and Menlo Park?
- Palo Alto R-1 allows 30 ft, or 33 ft with a roof pitch of 12:12 or steeper, and 17 ft in the single-story overlay [1]. Los Altos R1-10 allows 27 ft and two stories, dropping to 20 ft if coverage exceeds 30% [4]. Menlo Park R-1-U and R-1-S allow 28 ft on lots under 20,000 sq ft and 30 ft on larger lots [7],[8].
- Does a new house need design review in Los Altos?
- Yes. A new one-story house under 20 ft needs administrative design review. A new two-story house, a one-story house over 20 ft, or a one-to-two-story conversion needs Zoning Administrator approval at a noticed public meeting [6].
Sources
- [1] City of Palo Alto Municipal Code — 18.12.040 Site Development Standards (R-1) (Checked 2026-10-02)
- [2] City of Palo Alto Municipal Code — 18.12.090 Basements (Checked 2026-10-02)
- [3] City of Palo Alto Municipal Code — 18.12.110 Single Family Individual Review (Checked 2026-10-02)
- [4] City of Los Altos Municipal Code — Chapter 14.06 R1-10 Single-Family District (Checked 2026-10-02)
- [5] City of Los Altos Municipal Code — 14.02.010 Definitions (gross floor area, basement) (Checked 2026-10-02)
- [6] City of Los Altos Municipal Code — Chapter 14.77 Design Review (Ord. 2025-534) (Checked 2026-10-02)
- [7] City of Menlo Park Municipal Code — Chapter 16.16 R-1-U Single Family Urban Residential District (Checked 2026-10-02)
- [8] City of Menlo Park Municipal Code — Chapter 16.14 R-1-S Single-Family Suburban Residential District (Checked 2026-10-02)
- [9] City of Menlo Park Municipal Code — Chapter 16.67 Daylight Planes (Checked 2026-10-02)
- [10] City of Menlo Park Municipal Code — Chapter 16.04 Definitions (16.04.313 Floor area; 16.04.660 Structure) (Checked 2026-10-02)
- [11] City of Menlo Park Municipal Code — Chapter 16.59 Lots (16.59.010 Substandard lots) (Checked 2026-10-02)
- [12] City of Menlo Park Planning Division — Single Family Residential and R-2 Zoning Districts: FAL, Building Coverage, Daylight Plane and Balcony Restrictions (handout) (Checked 2026-10-02)
Published