San Anselmo — Overlay Districts

Last reviewed: July 2, 2026

Overview

San Anselmo’s zoning ordinance identifies a small set of overlay districts that modify or supplement base zoning rules rather than replace them. The ordinance specifically calls out the Residential Housing Opportunities (R‑HO) overlay, the Affordable Housing Overlay (AHO), and the Public Facilities (PF) and Open Space (OS) special districts (PF/OS function like overlays for special uses). For how overlays interact with the underlying zones, refer to the Town’s San Anselmo Zoning rules and the San Anselmo Development Standards table; the controlling text appears in the Municipal Code at § 10‑3.302 and § 10‑3.402.

Note: where design review or parking changes are involved, those processes remain governed by the Town’s design-review rules and parking standards. Linkages to affordable‑housing programs are handled in the Town’s Affordable Housing chapter and the Density Bonus chapter.

How to read this page

• Bold = terms you can scan for quickly (district names and numeric standards).
• The ordinance text itself is the source; I summarize and point to the exact controlling code sections (with the § citation) so you can verify. Where the code is silent, I mark it as "Not found in retrieved materials" or "Verify with the jurisdiction."

Overlay district-by-district breakdown

Each subsection below states the overlay’s stated purpose, the typical permitted uses or effect on permitted uses, how dimensional/quantitative standards are applied, and where it may (or is not yet) applied on the map.

Residential Housing Opportunities (R‑HO)

• Purpose: The R‑HO is an overlay intended to allow higher residential densities than the base zone when appropriate; it is described by the Land Use / Development Standards provisions as an overlay that “generally allows for higher residential densities.” Code: § 10‑3.302.
• Typical permitted uses / effect: Uses and uses-permissions remain those of the underlying zoning district (the overlay changes allowed density/intensity, not to create wholly new commercial uses). See the Land Use Regulations Table (Table 3A) for the underlying permitted uses. Code: § 10‑3.302.
• Key dimensional standards: The R‑HO “utilizes development standards for the underlying District” — i.e., setbacks, lot coverage, height and floor‑area ratio are the same as the base zone unless a specific amendment or planned development changes them. Code: § 10‑3.402.
• Where it applies: The ordinance explicitly says the R‑HO is “not yet designated on the zoning map and, therefore, is not currently regulated.” For any parcel, verify whether the overlay has since been placed on the Town Zoning Map. Code: § 10‑3.302.
• Practical note: Because the overlay is tied to increased density, projects proposed under an R‑HO must satisfy General Plan consistency and applicable findings for any discretionary approvals (e.g., design review or conditional use/planned development). See § 10‑3.901–10‑3.906 for planned development authority and findings referenced in the code.

Affordable Housing Overlay (AHO)

• Purpose: The AHO is expressly an overlay to the R‑3 and C‑3 zones intended to “enhance the development of affordable housing” by permitting greater densities and flexibility in development standards when a project dedicates at least forty percent (40%) of total units as deed‑restricted for low‑income households. Code: § 10‑3.402.
• Typical permitted uses / effect: The underlying zone’s uses remain in force (see Table 3A), but the AHO relaxes/adjusts standards (density, possibly lot‑coverage or other numeric controls) to enable affordable housing provided the 40% deed‑restriction threshold is met or as allowed by the Town’s affordable‑housing implementing rules. The overlay also gives the applicant an option to use the Town’s objective design standards (Title 3, Chapter 20) or the standard discretionary entitlement path. Code: § 10‑3.402; cross‑reference 10‑21 (Affordable Housing chapter) and the Density Bonus chapter (Title 10, Chapter 11) for program rules and enforcement details.
• Key dimensional standards: The overlay does not list a different fixed setback or height table inside the AHO text; instead, it makes clear that the project may seek greater density or flexibility from the standards in Table 4A if the affordability conditions are satisfied. That means base district numerical standards still exist (Table 4A), but discretionary increases are authorized by the overlay under the 40% requirement. Code: § 10‑3.402 and Table 4A.
• Where it applies: The AHO is an overlay shown on the Town’s zoning map where adopted. Always confirm by checking the official Zoning Map and the parcel’s zoning designation. Code: § 10‑3.202 and § 10‑3.402.
• Practical note: Projects using the AHO will also be subject to the Town's Affordable Housing Requirements (10‑21) for deed‑restriction, monitoring, and enforcement (e.g., affordability term requirements and in‑lieu fees where applicable). Code: § 10‑21‑030 et seq.

Public Facilities (PF) and Open Space (OS) (special / overlay‑like districts)

• Purpose: PF is applied to major public uses (Town Hall, library, Fire/Police, corporation yard) and OS is limited to passive recreation and parks. These districts do not carry a generic numeric table on Table 4A; PF/OS rely on either appropriate standards for the specific public use or on standards determined by the Planning Commission/Town Council. Code: § 10‑3.402 and § 10‑3.302.
• Typical permitted uses / effect: PF permits institutional/public facility uses (public buildings, schools, etc.); OS permits passive recreation uses. Where PF lands expand or are created, they require acquisition, General Plan amendment, or rezoning per the code. Code: § 10‑3.302, § 10‑3.402.
• Key dimensional standards: PF/OS are not listed with Table 4A standards in the code; PF uses are to use standards appropriate to the project or are established through Planning Commission or Town Council action. Code: § 10‑3.402.
• Where it applies: As shown on the Zoning Map; expansion of PF requires Town action. Code: § 10‑3.202 and § 10‑3.302.

Quick reference: most decision‑relevant overlay standards and triggers

Table notes: Numerical development standards for base zones (setbacks, heights, lot coverage, FAR, max stories) are published in Table 4A (Development Standards Table). Use Table 4A for the underlying numerical controls unless the overlay explicitly authorizes a change. See § 10‑3.402 / Table 4A.

How overlays interact with other rules (practical guidance)

• Overlay + underlying standards: Overlays are interpreted as modifying the underlying zone; unless the overlay text explicitly replaces a numeric standard it typically authorizes flexibility or higher density, not the wholesale removal of all base standards. Verify the overlay language and Table 4A. Code: § 10‑3.402.
• Design review: Projects in overlays that change building massing or density will usually trigger design review; the ordinance’s required findings apply (see § 10‑3.1506).
• Parking: If overlay increases density, consult the Town’s parking standards (Table 5A) and the State density‑bonus rules as implemented locally; some overlays allow parking flexibility only alongside a discretionary approval. Code: § 10‑11.050 and § 10‑3.503.
• Affordable housing compliance: AHO and any density bonus strategies must comply with the Town’s Affordable Housing chapter (10‑21) — monitoring, deed‑restriction term, in‑lieu fee rules, and enforcement measures are set there. Code: § 10‑21‑030 et seq.
• ADUs: Accessory dwelling units continue to follow the ADU chapter; overlays do not override ADU statutory protections. See the ADU rules in Chapter 6 and the ADU page for details. ADUs

Checklist (what an applicant must satisfy to use an overlay option)

• Confirm the parcel is located IN the overlay on the official Zoning Map (verify per § 10‑3.202).
• Confirm which overlay applies (R‑HO vs AHO vs PF/OS) and the overlay’s qualifying trigger (e.g., 40% deed‑restriction for AHO). Code: § 10‑3.402.
• Prepare a site plan and entitlement packet addressing consistency with the General Plan and Table 4A (or proposed deviations), and list which underlying standards will be adjusted. Code: § 10‑3.901 and § 10‑3.402.
• If using AHO, include proposed deed‑restriction language and evidence that at least 40% of units will be deed‑restricted to low income per Affordable Housing chapter rules. Code: § 10‑3.402 and § 10‑21‑030.
• Demonstrate compliance with any applicable density‑bonus request per the Town’s density bonus chapter and State law. Code: Title 10, Chapter 11 (Density Bonus).
• Confirm parking implications and supply a parking plan in conformance with Table 5A or requests for modified parking as part of the application. Code: § 10‑3.503 and Table 5A.
• Expect design review and required findings; prepare narratives addressing the findings in § 10‑3.1506.

Risks & Ambiguities

Plain‑English Summary

San Anselmo uses a small number of overlays — most importantly the Affordable Housing Overlay (AHO) and the not‑yet‑applied Residential Housing Opportunities (R‑HO) overlay — to allow denser or otherwise adjusted housing projects while keeping the base zone’s uses and standards in force. To use an overlay you must be located on the official Zoning Map and, for AHO, commit to the affordability requirement (at least 40% low‑income deed‑restricted units) and follow the Town’s affordable‑housing implementation rules; otherwise the base zone’s numeric standards (Table 4A) still apply. Verify a parcel’s overlays and required findings with Planning Staff before assuming any change in allowable density.

Source References

• § 10‑3.302 — Land Use Regulations Table; notes on R‑HO, PF, OS and Table 3A.
• § 10‑3.402 — Development Standards Table (Table 4A) and text describing the Affordable Housing Overlay (AHO) and how overlays interact with Table 4A.
• § 10‑3.202 — Zoning Map adoption and that the map controls district application.
• § 10‑3.1506 — Required findings for design review (useful when overlay changes trigger design review).
• Table 4A (Development Standards Table) — numeric district standards (setbacks, heights, FAR, lot coverage) referenced by overlays.
• Title 10, Chapter 11 (10‑11.01 et seq.) — Density Bonus provisions, application rules and interplay with local code.
• Title 10, Chapter 21 (10‑21‑010 et seq.) — Affordable Housing requirements, in‑lieu fees, enforcement and administration (used by AHO).
• Zoning map rules / boundary uncertainty: § 10‑3.204.

If you want me to: I can (1) check the Town Zoning Map against a specific parcel APN/address to confirm whether an overlay is actually mapped; or (2) draft the minimum application checklist for an AHO project (deed‑restriction language, financial pro forma, design‑review package). Verify with the jurisdiction for parcel‑specific interpretations.

Retrieved passages

• San Anselmo Zoning Code High relevance show source text
• San Anselmo Zoning Code (Article 9.) High relevance show source text
• San Anselmo Zoning Code (§ 1) High relevance show source text
• San Anselmo Zoning Code High relevance show source text
• San Anselmo Zoning Code (Title 3) High relevance show source text
• San Anselmo Zoning Code (section may) Medium relevance show source text
• San Anselmo Zoning Code (Section 10.3.1404) Medium relevance show source text
• San Anselmo Zoning Code (title across) Medium relevance show source text
• San Anselmo Zoning Code (Title 3) High relevance show source text
• San Anselmo Zoning Code (Article 13) High relevance show source text
• San Anselmo Zoning Code Medium relevance show source text
• San Anselmo Zoning Code (Title 11) Medium relevance show source text
• San Anselmo Zoning Code (Article 8) Medium relevance show source text
• San Anselmo Zoning Code (chapter and) Medium relevance show source text
• San Anselmo Zoning Code (§ 3) Medium relevance show source text
• CPC § 10 (Section 10-6.103) Medium relevance show source text
• San Anselmo Zoning Code (Section 10-3.1404) High relevance show source text
• San Anselmo Zoning Code (Section 10-3.404) Medium relevance show source text
• San Anselmo Zoning Code (§ 1) Medium relevance show source text
• San Anselmo Zoning Code (Section 5020.1) Medium relevance show source text
• San Anselmo Zoning Code (§ 1) Medium relevance show source text

Cited sections

• **§ 10‑3.302** — Land Use Regulations Table; notes on R‑HO, PF, OS and Table 3A. (§ 10)
• **§ 10‑3.402** — Development Standards Table (Table 4A) and text describing the **Affordable Housing Overlay (AHO)** and how overlays interact with Table 4A. (§ 10)
• **§ 10‑3.202** — Zoning Map adoption and that the map controls district application. (§ 10)
• **§ 10‑3.1506** — Required findings for design review (useful when overlay changes trigger design review). (§ 10)
• **Table 4A** (Development Standards Table) — numeric district standards (setbacks, heights, FAR, lot coverage) referenced by overlays.
• **Title 10, Chapter 11 (10‑11.01 et seq.)** — Density Bonus provisions, application rules and interplay with local code. (Title 10)
• **Title 10, Chapter 21 (10‑21‑010 et seq.)** — Affordable Housing requirements, in‑lieu fees, enforcement and administration (used by AHO). (Title 10)
• Zoning map rules / boundary uncertainty: **§ 10‑3.204**. (§ 10)
• SanAnselmo_ZoningCode.md

• Official San Anselmo code library