Local zoning · Portola Valley

Portola Valley — Variances and Exceptions

Q: How strict are the Portola Valley variance findings — what do I actually have to prove?

You must satisfy all six findings in § 18.68.070 : show special circumstances unique to the property (size, shape, topography), explain how literal enforcement would deprive the property of privileges enjoyed by nearby properties, show the variance will not create a special privilege or be detrimental, confirm the variance does not authorize a use not permitted in the zone, and demonstrate consistency with Title 18 and the General Plan. The Board will enter written findings when it approves or denies the request.

Variances and Exceptions under the Portola Valley local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

This page explains how the Town of Portola Valley handles variances and exceptions under Title 18 (Zoning). It summarizes who decides, the required findings, common exception paths (fences, antennas, floodplain relief), and how the rules differ across Portola Valley districts. Consult the specific code sections cited below for full legal text; this guide interprets those provisions in plain English. For related rules you will likely touch during an application, see the town’s pages on design review, parking, development standards, overlay districts, ADUs and the California Building Standards Code.

How Portola Valley treats variances and exceptions (top-level rules)

Who decides: the Planning Commission acts as the Board of Adjustment, which hears variance applications and appeals (see § 18.70.010 and § 18.66.010) .
Governing findings: a variance may only be granted when the Board finds all required facts (special circumstances, depriving property of privileges, no special privilege granted, not detrimental, not authorizing an unpermitted use, and consistency with Title 18 and the General Plan) — see § 18.68.070 (six required findings) .
Conditions and guarantees: the Board may attach conditions (yards, walls, parking surfacing, dedications, ingress/egress regulation, etc.) to protect public welfare and implement the Title and General Plan — see § 18.68.080 .
Time limits and lapse: the Board may require a development timetable (§ 18.68.120) and any unexercised variance lapses per § 18.34.150/18.68.130 unless timely exercised or renewed .
Revocation: variances can be revoked/suspended for false information, failure to exercise the approval, noncompliance with conditions, etc., with a hearing required (§ 18.34.170) .

Special-case variance types (examples you will encounter):

Floodplain variances follow the detailed flood chapter rules and stricter findings (minimum necessary; historic structure provisions; developer notices and recording on title) — see § 18.32.150 and related flood provisions (18.32.030–160) .
Programmatic exceptions for accessory elements (fences, antennas) are handled under specific exception sections (e.g., § 18.42.040 for fences and § 18.42.050 for antennas) and often require ASCC (Architectural & Site Control Commission) findings or ASCC/Board review .

Below are district-by-district notes (actual Portola Valley districts) because the interplay of variance/exception rules depends on the applicable district standards.

R-1 (Single-Family Residential)

Purpose & where it applies: R-1 regulates rural/single-family residential uses; accessory uses and conditions are specified in the R-1 chapter (see § 18.14.040–050) .
Typical permitted uses: single-family dwellings and accessory uses authorized by Section 18.36 and Chapter 18.42; accessory structures follow Chapter 18.42 rules (e.g., fences) .
Key dimensional standards: base parcel area and yard depths derive from Table No. 1 / Table No. 2 in Chapter 18.48 (e.g., Front: 20–50 ft / Side: 5–20 ft / Rear: 20–25 ft depending on the combining district/parcel size); confirm the exact combining district row for your lot in § 18.48.010 and Table No. 1/2 .
How variances/exceptions typically apply: most R-1 variance requests are for setback reductions, minor coverage increases, or lot-shape-driven relief; the Board will weigh § 18.68.070 findings and may attach ASCC or parking conditions (see § 18.68.080 and design review interplay) . See also ADU rules that provide alternative ministerial paths for accessory units (link to ADUs) .

R-E (Estate Residential) and M-R (Mountainous-Residential)

Purpose & where it applies: R-E and M-R permit low-density, larger-lot residential development designed to preserve natural terrain; rules and special PUD reductions are in Chapters 18.50 and 18.26/18.10 as applicable (see § 18.50.050 for planned unit development exceptions) .
Typical permitted uses: low-density single-family, agricultural/open uses; accessory uses per Chapter 18.42 apply .
Key dimensional standards: minimum parcel areas are large (1 acre, 2 acres, etc. rows in Table No. 1), required yards commonly Front: 50 ft, Side: 20 ft, Rear: 20–25 ft depending on parcel size/combining district (§ 18.48.010, Table 1/2) .
How variances/exceptions typically apply: steep slope, lot-shape, or ground-movement mapping (see ground movement categories in Table No. 1A/1B) often drive variance requests; the planning commission can authorize some PUD reductions where the commission finds less environmental disturbance (see § 18.50.050(B)) . Floodplain relief still follows Chapter 18.32 where applicable .

O-A (Open Area / Special)

Purpose & where it applies: O-A protects open space and scenic lands and is described in § 18.26.010; typical minimum parcel area and yard depths are larger (see Table No. 2) .
Typical permitted uses: low-intensity open-space uses, parks, and limited development listed in § 18.26.020–040; some conditional uses allowed by planning commission action .
Key dimensional standards: Minimum parcel area: 3 acres (Table No. 2 sample row) with Front: 50 ft, Rear: 25 ft, Side: 25 ft, Height limit: 28 ft, coverage and FAR limits per Table No. 2 (§ 18.48.010 / Table No. 2) .
How variances/exceptions typically apply: because the O-A district emphasizes preservation, the Board and ASCC scrutinize variance requests heavily against general-plan consistency (see § 18.68.070(6)) .

R-MF (Multi-Family) and M-U (Mixed-Use)

Purpose & where it applies: R-MF and M-U have their own development standards (density, FAR, setbacks) and the variance rules apply when projects cannot meet those numeric limits; see § 18.15.050 (R-MF dev. standards) and § 18.23.050 (M-U dev. standards) for the matrix of setbacks, FAR, coverage, and parking expectations .
How variances/exceptions typically apply: dimensional relief (yards, height, or coverage) may be requested but the Board will check compatibility and may require additional mitigating conditions (landscaping, parking screening, LAR/IAR mitigation) under § 18.68.080 .

Quick reference table — decision-relevant variance & exception points

Decision issue	What the Town requires (plain-English)	Code reference
Findings to grant a variance	All 6 findings must be satisfied (special circumstances; deprivation of privileges; no special privilege; not detrimental; variance not authorize a prohibited use; consistency with Title/General Plan)	§ 18.68.070
Conditions Board may impose	Special yards/open space, fences/walls, parking surfacing, dedication/road work, ingress/egress regulation, deed restrictions, monitoring	§ 18.68.080
Floodplain variances	Stricter test: minimum necessary, special notice/recording on title, engineering certification, special findings (no increased flood heights)	§ 18.32.150 & related flood ch. 18.32.030–160
Fence exceptions	Fences allowed in required yards subject to Chapter 18.43 principles and § 18.42.040 height limits; ASCC review for residential districts where indicated	§ 18.42.040 & Ch. 18.43
Antenna exceptions	Side/rear yard placement possible only with ASCC approval and findings about visibility, screening, emergency access	§ 18.42.050
Expiration / renewal	Variance lapse rules: exercise within one year (or Board’s time limit); may apply for one-year renewal	§ 18.34.150, § 18.68.120–130
Appeals & review bodies	Board of Adjustment hears appeals; appeals to Council governed by Chapter 18.78; ASCC decisions may be appealed to BOA	§ 18.66.010, § 18.78.010

Checklist (what the applicant must show / submit)

A complete variance application filed with the Board of Adjustment secretary and fee paid (follow § 18.68.020 and § 18.68.040) .
Site plan, architectural drawings, and any engineering reports required by staff/ASCC (the Board may require the site/architectural materials to be conditioned in the approval — § 18.68.080) .
For floodplain variances: registered engineer/architect floodproofing certification and acknowledgement of insurance/title-recording notice (see § 18.32.140–150) .
Evidence addressing each of the six variance findings in § 18.68.070 (special circumstances, hardship, no detriment, etc.) with photos, topography, and alternatives analysis .
CEQA initial study or EIR materials if staff determines CEQA is required (§ 18.68.025) .
If the proposal also triggers ASCC review or design review, include materials needed for that review; design/ASCC approvals can be coordinated (see Ch. 18.64 and the ASCC appeal path) and time limits may align with an ASCC approval (§ 18.34.150.B) .
For antenna exceptions, demonstrate lack of feasible alternative, visual screening, and emergency access compliance for § 18.42.050 findings .

Risks & Ambiguities

Issue	Why it matters	What to verify
Can the Board grant the exact relief requested?	Board cannot authorize a use not allowed by the zone — you cannot use a variance to change use rights (§ 18.68.070.A.5)	Verify the requested relief is purely dimensional/technical; confirm permitted uses in the district (see district chapters)
Floodplain variance special records	Flood variances trigger mandatory notices and title recording and carry insurance implications (§ 18.32.150.D)	If property touches the floodplain, get floodplain-admin guidance and expect recorded notices and higher insurance; obtain required engineer certifications
Overlap with ASCC/design review	The ASCC may need to approve aesthetics/setbacks and conditions; sometimes a variance and ASCC approval are issued together with matching expirations (§ 18.34.150.B)	Confirm whether your parcel requires ASCC review and whether applications will be bundled; ask staff if the ASCC is the primary reviewer
Time limits and lapse	Variances lapse if not exercised within the Board’s limit or one year if unspecified (§ 18.34.150, § 18.68.120–130)	If construction will be delayed, plan to request a time-limit extension or renewal before lapse dates
Parcels with special combining or overlay rules	Combining districts (slope density, ground movement) change allowed floor area/impervious surface; exceptions may be limited	Verify combining-district status on your parcel and compute adjusted maxima using Tables 1/1A/1B (§ 18.48.010 and Table No.1/1A/1B)
Post-approval compliance & revocation	Approvals can be revoked for noncompliance or false information (§ 18.34.170)	Keep written records of conditions, meet monitoring requirements, and consult the planner if conditions become impossible to meet

Plain-English summary

Portola Valley treats variances as exceptional, discretionary relief: the Board of Adjustment (planning commission acting in that role) will only approve them when strict findings are met, conditions to protect neighbors are included, and any required design or flood protections are in place — see § 18.68.070, § 18.68.080, and the flood chapter § 18.32.150 for the stricter flood rules.

Source References

Portola Valley Title 18 — VARIANCES: § 18.68.010–180 (applicability, application, findings, conditions, time limits, appeals) .
Portola Valley Title 18 — UNEXERCISED/REVOCATION/FEES: § 18.34.140–170 (exercise/expiration/renewal, revocation grounds) .
Portola Valley Title 18 — FLOODPLAIN VARIANCES: § 18.32.030–160, especially § 18.32.140–150 (floodproofing & flood variance criteria and notice/recording) .
Portola Valley Title 18 — EXCEPTIONS FOR ACCESSORY STRUCTURES: § 18.42.040 (fences) and § 18.42.050 (antennas) and Chapter 18.43 (fence standards) .
Portola Valley Title 18 — TABLES & DISTRICT STANDARDS: § 18.48.010 and Table No.1/Table No.2 (parcel area, yards, height, floor area, impervious surface computations) .
Portola Valley district chapters consulted: § 18.14 (R-1), § 18.15 (R-MF), § 18.23 (M-U), § 18.26 (O-A), § 18.50 (slope/combing district rules) .
California Building Standards references (flood/residential variance context) — see the state code guidance in the CBC Appendix/Section on variances (see local implementation via flood chapter) — consult the California Building Standards Code for state-level building/flood references.

If you need a parcel-specific read of how the district/combining districts apply to a single lot (exact setbacks, FAR, impervious surface maxima), provide the Assessor parcel number or street address and I can translate the correct Table row and list the exact variance exposures to expect. Verify with Town planning staff for any procedural questions or to confirm whether an ASCC review will be required.

Sources

Retrieved passages

Portola Valley Zoning Code (chapter have) High relevance
Portola Valley Zoning Code (§ 1) High relevance
Portola Valley Zoning Code (§ 2) High relevance
Portola Valley Zoning Code (chapter is) Medium relevance
Portola Valley Zoning Code (§ 1) Medium relevance
Portola Valley Zoning Code Medium relevance
Portola Valley Zoning Code (§ 27) Medium relevance
Portola Valley Zoning Code (Chapter 18.66) Medium relevance
Portola Valley Zoning Code (title would) High relevance
Portola Valley Zoning Code (Section 18.34.090) High relevance
Portola Valley Zoning Code (title of) High relevance
Portola Valley Zoning Code (section of) Medium relevance
Portola Valley Zoning Code (§ 5) Medium relevance
Portola Valley Zoning Code (§ 1) Medium relevance
Portola Valley Zoning Code (Chapter 18.54.040) Medium relevance
Portola Valley Zoning Code (§ 6) Medium relevance
Portola Valley Zoning Code (Chapter 18.72) Medium relevance
Portola Valley Zoning Code (Section 18.36.020) Medium relevance
Portola Valley Zoning Code (§ 1) Medium relevance
Portola Valley Zoning Code (§ 1) Medium relevance

Cited sections

Official Portola Valley code library

Frequently asked questions

How strict are the Portola Valley variance findings — what do I actually have to prove?

You must satisfy all six findings in § 18.68.070: show special circumstances unique to the property (size, shape, topography), explain how literal enforcement would deprive the property of privileges enjoyed by nearby properties, show the variance will not create a special privilege or be detrimental, confirm the variance does not authorize a use not permitted in the zone, and demonstrate consistency with Title 18 and the General Plan. The Board will enter written findings when it approves or denies the request.

Can I use a variance to build a use that is not allowed in my zoning district?

No — the ordinance expressly forbids granting a variance that authorizes a use not authorized in the underlying zone (see § 18.68.070.A.5). Variances are limited to relief from numeric or dimensional requirements, not changes to allowed land uses.

What’s different about floodplain variances in Portola Valley?

Floodplain variances follow the detailed Chapter 18.32 rules: the variance must be the minimum necessary, the floodplain administrator requires engineering certification, and the applicant receives a written notice about insurance consequences that is recorded on title; the Board considers flood-specific factors like flood heights, access and community cost (§ 18.32.140–150). Expect stricter review and formal recorded notices.

If the ASCC must review my project, how do ASCC and variance timelines interact?

When a single project requires both a variance and ASCC (architectural) approval and they are considered together, the variance will have the same expiration period as the ASCC approval; otherwise standard lapse/renewal rules apply (§ 18.34.150.B). Always confirm with Planning staff whether reviews will be consolidated.

Can I appeal a variance denial and how quickly must I act?

Yes — appeals from BOA/ASCC decisions follow Chapter 18.66/18.78 procedures; a written notice of appeal must generally be filed within 15 days of the decision that is being appealed (§ 18.66.020, § 18.78.020). Check the exact form and transmittal requirements in those sections.

Do fence and antenna exceptions require a variance?

Not always. Portola Valley has specific exception rules: fences in residential and certain districts follow Chapter 18.43 and § 18.42.040 height limits; antennas can be located in side/rear yards only if approved by ASCC under findings in § 18.42.050. Some cases need ASCC review rather than a variance; others may require both.

What happens if I get a variance and then don’t start construction?

A variance “lapses” if not exercised within the Board’s specified time or within one year if no time is set (see § 18.68.120 and § 18.34.150); you can apply for a one‑year renewal before expiration. If work doesn’t proceed, the variance can become null and void.

Can the Town revoke a variance later?

Yes — the Town may revoke, suspend or modify a variance for reasons such as false information, failure to exercise within required timeframes, noncompliance with conditions, or violation of other laws; revocation requires a public hearing (§ 18.34.170 and cross-references in the variance chapter).

How do combining districts (slope density, ground movement) affect variance requests?

Combining districts change allowable parcel area, maximum floor area, coverage and impervious-surface computations (Tables 1/1A/1B). Variances for floor area or coverage must address the combining-district rules in Chapter 18.48 and Chapter 18.50; the Board will consider whether the special circumstances are truly unique to the parcel given those combining rules. Compute adjusted maxima per § 18.48.010 and Tables 1/1A/1B before applying.

If I’m only trying to add an ADU, do I need a variance?

Most ADUs are now governed by the ADU chapter and state ADU law; many ADU standards are ministerial but some ADU proposals still trigger discretionary review or ASCC decisions (see the ADU chapter and appeal provisions). If the ADU requires relief from a numeric standard not allowed under the ADU chapter, you may still need a variance; check local ADU rules and appeal paths in the ADU chapter (see ADU administration and appeals)

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