Commercial Real Estate in Portola Valley: C-C and A-P Districts, Alpine Road Mixed Use and Geologic Maps

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

Portola Valley is a small, largely residential town in the hills south of Menlo Park, and its commercial land is limited to a few parcels along Alpine and Portola Roads. Those parcels hold community shopping, local services, small offices, institutions and, since 2024, a mixed-use district aimed at housing. The town’s zoning deliberately keeps commerce local and small, and its geologic hazard maps shape what can be built anywhere in town. Confirm zoning and geologic conditions for each parcel with the Town of Portola Valley before relying on this page.

Who controls the parcel

Portola Valley is an incorporated town. Title 18 of its municipal code is the zoning ordinance, and Section 18.06.010 lists the districts, most recently amended by two 2024 ordinances. Some neighborhoods near the town, such as Ladera and Los Trancos Woods, are unincorporated and zoned by San Mateo County under its own S-districts; see our San Mateo County commercial guide.

Projects in town go through the Architectural and Site Control Commission (ASCC) and Planning Commission. The C-C chapter requires site plan and architectural approval for most uses and structures.

Portola Valley zoning for commercial, industrial and mixed use

District	Intended uses	Notes
C-C Community Commercial (18.20)	Local retail, consumer services and professional services for the town	Most retail, restaurants and gas stations by conditional use permit. Parcels over 20,000 sq ft must be planned unit developments
A-P Administrative-Professional (18.22)	Offices	Shares a 5,000 sq ft town-wide cap on small personal offices with C-C; we did not review its chapter
MU Mixed-Use (18.23)	Multifamily housing with local retail and services	3 to 6 homes an acre. FAR 0.28 residential, 0.22 nonresidential. 34 ft. Applied to 4370 and 4394 Alpine Road
P-C Planned Community (18.28)	Master-planned areas	Not reviewed
H-R Historic Resource (combining, 18.31)	Historic properties	Not reviewed
D-R, F-P and S-D (combining)	Design review, floodplain and slope density	Listed in Section 18.06.020

What a C-C parcel can do

The C-C chapter is unusual in how little it allows by right. Its purpose is retail and services that mainly serve the town and are compatible with nearby homes.

Conditional use permit. Most ordinary storefront uses need a conditional use permit, and most of them are also subject to floor area limits in Section 18.54.052. That includes:

apparel shops, bakeries, banks, barbers and salons
drug stores, food stores, hardware stores and nurseries
package liquor stores
restaurants and bars ("eating and drinking places"), except drive-ins and places with entertainment and dancing
gas stations with washing, lubrication and minor repair

Office limits. Office space in C-C is generally held to 15% of a building’s net floor area. The Planning Commission can raise that to 50% with a conditional use permit. Small personal offices of 150 to 350 square feet are capped at 5,000 square feet across C-C and A-P combined.

Other conditions. Uses must be inside buildings, except for fuel service, parking, outdoor dining, nurseries and a few others. On-site processing is limited to half the floor area and three employees. A parcel over 20,000 square feet must be developed as a planned unit development.

Housing in C-C. An existing single-family home can remain as an interim use for a period the Planning Commission approves.

The 2024 Alpine Road mixed-use district

The town added the MU district in 2024 to pair multifamily housing with local retail and services. The chapter names two parcels, 4370 and 4394 Alpine Road, and ties them to the 2023–2031 Housing Element.

Permitted. Housing is permitted outright: single-family, duplex and multifamily homes, supportive and transitional housing, and emergency shelters.
Conditional. Offices, medical and dental clinics, fitness, veterinary and real estate offices, and C-C type uses need a conditional use permit.
Standards. Density runs from 3 to 6 units an acre. FAR is 0.28 for residential and 0.22 for nonresidential uses, and height is 34 feet. At 4370 Alpine Road, building within 50 feet of the Nathhorst Avenue line is limited to one story. Some standards do not apply inside a Supportive Housing Overlay.

Geologic maps, creeks and floodplains

Town geologic maps. On November 8, 2017, the Town Council approved a Geologic Map and a Ground Movement Potential Map. It adopted them as policy and guidelines for town decisions, with land use policies set out in Resolution 2746-2017. The town says decisions should follow the maps unless they are modified or a deviation is permitted. Any commercial addition or rebuild should start by locating the parcel on both maps and reading the resolution’s policy for its map unit.

Creeks and floodplain. The town has a creek setback chapter (18.59) and a Floodplain combining district (Chapter 18.32), and the C-C chapter applies flood zone rules. Parcels near creeks along Alpine Road warrant a setback and flood check.

Slope density. The S-D slope density combining district can reduce what steeper parcels may hold.

Transfer tax, business tax and property tax

The San Mateo County Assessor-County Clerk-Recorder collects documentary transfer tax at recording at 55 cents per $500. The County’s page names only the City of San Mateo as adding a city tax, and we found no Portola Valley transfer tax; confirm on the escrow estimate. A sale generally triggers Proposition 13 reassessment. We did not verify a town business license tax.

Due diligence that matters in Portola Valley

Start with our commercial due diligence checklist, then add:

Confirm town versus County jurisdiction; Ladera and Los Trancos Woods are County areas.
Pull every conditional use permit; most C-C tenants depend on one.
Check floor area limits under Section 18.54.052 and the office share of the building.
Locate the parcel on the 2017 geologic and ground movement maps and read Resolution 2746-2017.
Check creek setbacks and floodplain status.
For MU parcels, review Housing Element obligations before planning a commercial-only project.

Questions people ask

Can a restaurant open in Portola Valley?

In C-C, with a conditional use permit; drive-ins and places with entertainment and dancing are excluded.

How much office space is allowed?

Generally 15% of a C-C building’s floor area, up to 50% with a use permit. Small personal offices are capped at 5,000 sq ft town-wide.

What is the MU district?

A 2024 mixed-use district for 4370 and 4394 Alpine Road, pairing housing at 3 to 6 units an acre with local retail and services.

Why do geologic maps matter so much here?

The Council adopted them in 2017 as policy for town decisions, with land use policies in Resolution 2746-2017.

Must large commercial sites be planned developments?

Yes. C-C parcels over 20,000 sq ft must be developed as planned unit developments.

Is there a town transfer tax?

We found none. The County tax is 55 cents per $500.

Does Diamond handle commercial property in Portola Valley?

Contact Matthew Martinez to discuss buying, selling or leasing commercial property in Portola Valley.

Sources & notes

Note: We did not review the A-P chapter, Section 18.54.052 floor area limits, the map PDFs or Resolution 2746-2017 itself.

This page is general information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.

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