Los Altos Hills — Nonconforming Uses

Last reviewed: July 2, 2026

Overview

Los Altos Hills treats nonconforming uses and structures as a legacy legal status that can be maintained in limited ways but not expanded. The town’s Zoning & Site Development Code sets rules for continuation, repair/rebuilding, abandonment, and small additions to nonconforming structures; it also ties reconstruction rights to documentation verified by the Planning Director. See the town’s zoning rules for context on district rules and development limits. Verify with the jurisdiction for parcel‑specific determinations. (§ 10-1.401; § 10-1.402)

How the ordinance frames Nonconforming Uses (core rules)

• Continuation: A nonconforming use may be continued but may not be changed, enlarged, or altered (use or structure) unless changed to a permitted use under the code. § 10-1.402

• Abandonment/Discontinuance: A nonconforming use is permanently lost if discontinued or abandoned for 180 days or more in a 12‑month period. § 10-1.404

• Repair, Rebuild, Reconstruction after Damage:

  • The code allows rebuilding of damaged/destroyed legal nonconforming structures so long as the work does not increase the existing nonconformity or change the use. § 10-1.401(a)
  • Work from casualty events (fire, Act of God) is allowed provided expense does not exceed 50% of the appraised value at time of damage for certain situations (§ 10-1.405).

• Maintenance, cumulative repairs, and limits on alterations:

  • Ordinary repairs and maintenance are allowed; structural alterations or changes of use require authorization (Planning Commission conditional use permit where applicable). The code caps cumulative structural repairs/alterations at 50% of the then‑appraised value unless the use is converted to conforming. § 10-1.406

• Additions: The Planning Director may approve small additions up to 150 sq ft into a setback and up to one story / 19 ft tall if specific findings are met (continuation of building edge, no closer to property line, no adverse privacy/visual impacts, consistency with floor area/development area rules). § 10-1.401(g)

• Increase in Nonconformity: Any alteration that increases footprint, volume, height, development area, floor area, or encroachment extent is treated as an increase in nonconformity and is not allowed absent the required approvals. § 10-1.401(i)

• Documentation & Verification: For rebuilds or partial demolitions, pre‑demolition dimensions, square footage and uses must be submitted and verified by the Planning Director before issuing demolition or site development permits. Time limits for resubmittal (generally 1 year after voluntary demolition; 2 years after casualty in some cases) are imposed; the City Council may grant extensions. § 10-1.401(b)–(e)

• Relationship to variances and conditional permits: The code explicitly allows property owners to seek variances or conditional permits where the code provides. § 10-1.401(k)

District‑by‑district breakdown (where nonconforming rules intersect district rules)

Note: Nonconforming provisions (Article 4) are generally townwide, but district rules determine the baseline standard that a structure or use no longer complies with. Below are the districts and the specific provisions retrieved from the town code. For full district rules see the Town’s zoning chapters. Link to the town’s zoning topics where you see related items such as development limits and parking.

• First mention of "zoning" link: Los Altos Hills Zoning

Residential‑Agricultural — R‑A

• Purpose & where it applies: The Residential‑Agricultural (R‑A) district is the Town’s primary single‑family and large‑lot residential district; its primary and accessory uses and conditional uses are set out in Article 7 of the code. § 10-1.701 – § 10-1.706

• Typical permitted uses: single‑family dwellings, accessory structures; some conditional institutional or community uses with Planning Commission approval. § 10-1.701–703

• Key dimensional/development standards that determine what "nonconforming" means here:

  • Area/coverage/floor area and height/setback limits are in Article 5; these thresholds are what trigger a nonconforming status when standards change. See § 10-1.501 (minimum parcel size) and Article 5 development area/floor area rules. § 10-1.501; Article 5

• How nonconforming rules apply: A building in R‑A that exceeds the current maximum development area or sits inside required setbacks is a legal nonconforming structure if lawfully established previously; repairs, limited additions (see 150 sq ft rule) and rebuilds are governed by Article 4. § 10-1.401; § 10-1.704

• When discussing development standards or setbacks, see Los Altos Hills Development Standards and Los Altos Hills Parking for off‑street parking requirements that cannot be reduced further for nonconforming sites without following the code. § 10-1.705

Open Space Reserve — OSR

• Purpose & where it applies: The Open Space Reserve (OSR) district preserves agricultural, forest, and other open space uses. § 10-1.801
• Typical permitted uses: agricultural uses, forest preserves, other open space activities; accessory structures limited to those needed to support the primary use. § 10-1.801–802
• Key dimensional standards: Area/coverage/height/setback rules still derive from Article 5 and apply to OSR as well (see § 10-1.803). § 10-1.803; Article 5
• How nonconforming rules apply: Nonconforming structures in OSR are treated under Article 4 (same townwide standards on repair, rebuild, and abandonment), but the permitted baseline uses in OSR are narrower—so a use nonconforming to OSR may be required to convert or remove if found hazardous or injurious by the Council. § 10-1.403

Upper Neary Quarry Lands (Special rules)

• Purpose: Special regulations limiting dwellings and siting apply to the Upper Neary Quarry Lands area; those rules also set maximum development area/floor area limits tied to the Residential‑Agricultural standards. § 10-1.901
• How nonconforming rules apply: Where special district standards differ, a structure lawful under prior rules will remain nonconforming and is subject to Article 4 repair/rebuild rules. § 10-1.401; § 10-1.901

Quick reference table — most decision‑relevant nonconforming standards

Practical guidance (plain‑English interpretation and process tips)

• If your building predates a code change and now violates a setback, floor‑area, or development‑area standard, it is likely a legal nonconforming structure rather than illegal; the town’s code defines that term and allows limited maintenance, repairs, and controlled rebuilds. § 10-1.401(h)

• Before you demolish or make large repairs, document the existing footprint, floor area, exterior wall area, and location of encroachments. The Planning Director must verify these measurements to preserve your right to rebuild the prior nonconforming development area or floor area. § 10-1.401(d)

• Small setback infill (e.g., a modest bay, closet, or bump‑out) may be administratively approved up to 150 sq ft and 19 ft in height by the Planning Director if specific findings are met — this is the main route for modest improvements without going to the Planning Commission. § 10-1.401(g)

• Major rebuilds that would increase the degree of nonconformity (bigger footprint, height increase, more development area) are disallowed unless the Planning Commission approves relocation or makes required findings; plan accordingly and expect discretionary review. § 10-1.401(i),(c)

• Nonconforming use rights can be lost via abandonment (the 180‑day rule). If you are temporarily closing a business or use, document intent to avoid a dispute about abandonment. § 10-1.404

• The code preserves the right to apply for variances or conditional development permits where strict application of the nonconforming rules would be inequitable; consider this route for unusual lots. § 10-1.401(k)

• Nonconforming zoning conditions may interact with state ADU rules (state ADU law limits how local agencies can deny ADU permits due to nonconforming conditions). See the town’s ADU policies and state law. Link to the town ADU page and state building code resources for next steps: Los Altos Hills ADUs and California Building Standards Code. For the state ADU rule summary included in the materials, see the provided ADU handbook.

• For discretionary review triggers (e.g., substantial remodels, site development permits), check the thresholds in the Site Development and permit procedures (a zoning permit or site development permit is required before building permits). § 10-1.310; Site Development thresholds

Also consider design review pathways if your project will change exterior appearance or site impacts — see Los Altos Hills Design Review and the town’s overlay rules at Los Altos Hills Overlay Districts.

Checklist — what an applicant must satisfy to preserve or rebuild a nonconforming structure

• Verify that the structure/use was previously lawfully permitted; obtain historic permits/records if available (legal nonconforming status). § 10-1.401(h)
• Before demolition or substantial alteration, submit pre‑demolition dimensions, floor area, development area, exterior wall area, and use documentation to the Planning Director for verification. § 10-1.401(d)
• Determine whether proposed work would increase the nonconformity (footprint, height, development/floor area, setback encroachment). If so, prepare for Planning Commission review or a variance. § 10-1.401(i),(k)
• For casualty rebuilds, confirm the 50% appraised value rebuild cap (for certain damage dates) and the 1 or 2‑year permit submittal deadlines. § 10-1.405; § 10-1.401(e)
• If proposing a small setback addition, prepare findings for the Planning Director showing continuance of building edge, no increased privacy/visual impacts, and compliance with floor area/development area limits (addition ≤ 150 sq ft, ≤ 19 ft). § 10-1.401(g)
• Obtain any required zoning permits, site development permits, and building permits in the correct sequence (zoning/site development permit required before building permits). § 10-1.310

Risks & Ambiguities

Plain‑English Summary

If your house or accessory building in Los Altos Hills doesn’t meet today’s zoning rules but was lawful when built, the town will generally let you keep, repair, or rebuild it — but you may not enlarge the nonconforming part, change it to a different nonconforming use, or abandon the use for long periods (180 days rule). Small exception: limited infill into setbacks (up to 150 sq ft, single story, ≤ 19 ft) can be approved by staff if it meets specific findings. Always document existing conditions and check with the Planning Director before demolishing or making major repairs. § 10-1.401–10-1.406

Source References

• Los Altos Hills Zoning & Site Development Code, Article 4: Nonconforming Uses and Structures, § 10-1.401 through § 10-1.406. Source: Los Altos Hills Municipal Code (ecode360) — § 10-1.401 ; § 10-1.402 – § 10-1.406
  URL: https://ecode360.com/LO4964 (Los Altos Hills Zoning & Site Development Code)
• Article 5 (Area, Coverage, Height and Setback Limitations), including § 10-1.501 (minimum parcel size), § 10-1.502 (development area), and related thresholds referenced for nonconforming rebuilds. § 10-1.501 – § 10-1.503
• Article 7 (Residential‑Agricultural District R‑A), § 10-1.701 – § 10-1.706 (permitted, accessory, conditional, and prohibited uses) — § 10-1.704 – § 10-1.706
• Article 8 (Open Space Reserve OSR), § 10-1.801 – § 10-1.804 (permitted accessory uses and prohibited uses) — § 10-1.801 – § 10-1.804
• Zoning permit rules and procedural thresholds: § 10-1.310 (zoning permits required before building permits)
• ADU / state law summary included in provided materials (ADU handbook): on interaction of ADU approvals and nonconforming zoning conditions (state law limits) — ADU handbook (2025) provided in user materials.

Retrieved passages

• Los Altos Hills Zoning Code (section is) High relevance show source text
• Los Altos Hills Zoning Code (§ 10-1.403) High relevance show source text
• Los Altos Hills Zoning Code (chapter shall) High relevance show source text
• Los Altos Hills Zoning Code (§ 10-1.310) High relevance show source text
• Los Altos Hills Zoning Code (§ 10-1.401) High relevance show source text
• Los Altos Hills Zoning Code (chapter shall) High relevance show source text
• Los Altos Hills Zoning Code (§ 1) High relevance show source text
• Los Altos Hills Zoning Code (Article 7) High relevance show source text

Cited sections

• Los Altos Hills Zoning & Site Development Code, Article 4: **Nonconforming Uses and Structures**, **§ 10-1.401** through **§ 10-1.406**. Source: Los Altos Hills Municipal Code (ecode360) — **§ 10-1.401** ; **§ 10-1.402 – § 10-1.406** (Article 4)
• Article 5 (Area, Coverage, Height and Setback Limitations), including **§ 10-1.501** (minimum parcel size), **§ 10-1.502** (development area), and related thresholds referenced for nonconforming rebuilds. **§ 10-1.501 – § 10-1.503** (Article 5)
• Article 7 (Residential‑Agricultural District **R‑A**), **§ 10-1.701 – § 10-1.706** (permitted, accessory, conditional, and prohibited uses) — **§ 10-1.704 – § 10-1.706** (Article 7)
• Article 8 (Open Space Reserve **OSR**), **§ 10-1.801 – § 10-1.804** (permitted accessory uses and prohibited uses) — **§ 10-1.801 – § 10-1.804** (Article 8)
• Zoning permit rules and procedural thresholds: **§ 10-1.310** (zoning permits required before building permits) (§ 10-1.310)
• ADU / state law summary included in provided materials (ADU handbook): on interaction of ADU approvals and nonconforming zoning conditions (state law limits) — ADU handbook (2025) provided in user materials.
• LosAltosHills_ZoningCode.md
• 2025 California ADU handbook.md

• Official Los Altos Hills code library