Foster City — Overlay Districts

Last reviewed: July 2, 2026

Overview

Foster City’s Title 17 uses a mix of combining/overlay districts (often called “combining districts” or “overlay combining districts”) to modify base zoning where special policy goals apply, especially for housing and phased development. The primary overlay/combing districts in the code are the PD (Planned Development Combining District), Senior Housing Overlay District, Affordable Housing Overlay (AHO) Combining District, By‑Right Housing Overlay (BRHO) Combining District, and the X (Future Development) Combining District; the list of allowable combining districts is set out in § 17.10.020.

(First mention links: the Foster City zoning code and related permitting topics are summarized in the city planning pages — see the city's Foster City Zoning overview and the Foster City Land Use page for how overlays map to general plan land use.)

How overlay districts are used in Foster City

• Overlay/combining districts are applied in addition to a parcel’s base zoning and are used only in combination with a primary district unless the overlay chapter says otherwise; creation/removal follows the procedures set out in the code (typically Chapter 17.74). See § 17.10.040 and repeated establishment clauses in each overlay chapter.

• Where an overlay is “floating” or “combining,” the code typically requires application by the property owner or action by the planning commission/city council to attach it to a parcel. See the establishment language in § 17.36.020, § 17.37.040, § 17.92.020, and § 17.94.020.

District-by-district breakdown

Note: each subsection below states the chapter used in Title 17 and gives the practical effect. For development standards and site-level measurements consult the city's Foster City Development Standards and the base district chapters referenced in each overlay.

PD — Planned Development Combining District (Chapter 17.36)

• Purpose: Provide flexibility of design to accommodate a variety of developments (single‑family subdivisions, multifamily, shopping centers, offices, industrial parks) while aligning with the general plan. § 17.36.010.
• Typical permitted uses: Same spectrum as primary districts but implemented via a general development plan and specific development plan; conditional uses are identified in the PD approval documents. See § 17.36.010–§ 17.36.050.
• Key dimensional / procedural standards:
  • PDs may waive certain ordinary zoning standards upon planning commission approval without a variance (the chapter lists categories that can be modified). § 17.36.020(B) and § 17.36.130.
  • A use permit in a PD typically expires in two years unless otherwise stated; extensions follow the code’s permit extension rules. § 17.36.110.
  • Off‑street parking requirements in a PD are specifically addressed in § 17.36.060 (PDs may have their own parking provisions). (When you are planning parking counts, also consult the city’s Foster City Parking standards.)
• Where it applies: PD is a combining district attached to a base zone by application or initiative; its terms supersede or modify other Title 17 provisions only where the PD text does so. § 17.36.020, § 17.36.130.

Senior Housing Overlay District (Chapter 17.37) — Senior Housing Overlay

• Purpose: A floating overlay used only in conjunction with a PD to facilitate affordable rental housing for seniors through incentives, while ensuring long‑term affordability and compatibility with surrounding areas. § 17.37.010–§ 17.37.030.
• Typical permitted uses: Affordable senior rental housing projects developed under a PD; uses are constrained to be compatible with senior living (no heavy industrial, etc.). § 17.37.040 (establishment conditions) and § 17.37.030 (policies).
• Key incentives / dimensional effects:
  • The overlay offers incentives such as reduced off‑street parking requirements, dwelling unit density bonuses, reduced unit sizes, fee waivers/reductions, and priority/fast‑track processing; incentives are negotiated case‑by‑case. § 17.37.050(A).
  • Projects receiving incentives must enter into a development agreement to secure long‑term affordability. § 17.37.060.
  • The chapter states that, except where specified, the PD provisions apply but Section 17.36.060 (PD parking rules) does not apply in certain parts where the overlay grants parking exceptions; the overlay specifically modifies the application of Chapter 17.62 for portions of a senior project. § 17.37.030(G–H).
• Where it applies: Floating; applied only by PD and only when conditions (compatible surrounding uses, infrastructure, proximity to amenities) are met. § 17.37.040.

Affordable Housing Overlay (AHO) — Affordable Housing Overlay Combining District (Chapter 17.92)

• Purpose: Encourage below-market‑rate rental units for extremely low, very low and low income households on sites designated Apartment Residential in the general plan; offers an alternative inclusionary path to Chapter 17.90. § 17.92.010.
• Typical permitted uses: Apartment residential projects that include the required BMR units as specified in the chapter; eligibility is limited to properties with the apartment residential general plan designation. § 17.92.020.
• Key requirements:
  • The AHO is established/removed via the procedures in Chapter 17.74; only properties designated apartment residential are eligible. § 17.92.020.
  • The chapter incorporates definitions from § 17.90.020 and the below-market rate unit inclusion rules in § 17.92.040 (which tie back to Chapter 17.90). § 17.92.030–040.

BRHO — By‑Right Housing Overlay Combining District (Chapter 17.94)

• Purpose: A by‑right overlay to encourage below‑market‑rate rental units for lower income households on sites designated apartment residential, and to allow ministerial (objective) review of qualifying multi‑family projects that meet the chapter’s conditions. § 17.94.010.
• Typical permitted uses: Multifamily development that provides the specified percentage of affordable units as required by the chapter; such projects may proceed without discretionary review if they meet the objective criteria. § 17.94.040–§ 17.94.050.
• Key requirements / effects:
  • 20% of proposed units must be affordable to lower‑income households to qualify for by‑right treatment; fractional unit rounding rules apply. § 17.94.040(A)(1–2).
  • Applications under the chapter are ministerial and reviewed by the Community Development Director for objective compliance; the director may deny or approve with objective conditions or refer to planning commission for comment on objective design standards. § 17.94.050.
  • Establishment/removal follows Chapter 17.74 procedures. § 17.94.020.

X — Future Development Combining District (Chapter 17.38) — X combining district

• Purpose: Designate lands temporarily unsuitable for development (lack of services, poor physical condition), so the city can control future timing and conditions before full development is allowed. § 17.38.010.
• Typical permitted uses: Uses allowed in the OSC (Open Space‑Conservation) district apply while the X combining district remains in effect; conditional uses follow code rules for X. § 17.38.030–040.
• Key procedural points:
  • X districts are attached/removed via the Chapter 17.74 procedures and must align with the general plan. § 17.38.020.

Other combining district mentions

• The code explicitly lists PD, X, and W (aquatic development) as combining districts in § 17.10.020; the code allows other combining districts in Chapters 17.36–17.40 and elsewhere (for example, the separate chapters for 17.37, 17.92, 17.94). § 17.10.020.
• Where a given overlay modifies another code chapter (for example, parking in Chapter 17.62 or architectural review in Chapter 17.58), that modification is expressed in the overlay chapter text — check each overlay chapter for exceptions. See Senior Overlay and BRHO examples above.

Quick reference table — overlays and the most decision‑relevant rules

Practical guidance & synthesis

• Confirm base zoning and the parcel’s General Plan land‑use designation first; many overlays require specific GP designations (for example, AHO and BRHO require the apartment residential GP designation). See § 17.92.020 and § 17.94.010. (Use the Foster City Land Use page as your starting map.)
• Overlays frequently modify or supersede parts of the base zoning or other Title 17 chapters (parking Chapter 17.62, design review Chapter 17.58, development standards). Always check the overlay chapter for explicit exceptions (for example, Senior Overlay parking exceptions in § 17.37.030(H)). (For parking specifics consult the Foster City Parking guidance.)
• Projects relying on incentives (reduced parking, density bonuses, fee waivers) will require negotiated agreements and, in many cases, recorded obligations (e.g., a development agreement for senior projects). § 17.37.050–060.
• For housing overlays that allow by‑right or ministerial review (BRHO), pay close attention to objective thresholds (affordability percentages, unit rounding rules); failure to meet these objective thresholds converts the project to discretionary review. § 17.94.040–050.
• Design and architectural compliance remains required; architectural review findings are spelled out in Chapter 17.58 and are incorporated into the approval standards the planning/approval body uses. § 17.58.050–060. (See Foster City Design Review.)

Checklist — what an applicant must satisfy for an overlay application in Foster City

• Verify the parcel’s General Plan designation (some overlays require Apartment Residential). § 17.92.020, § 17.94.010.
• Confirm that the chosen overlay is allowed to attach to the parcel (floating vs. map overlay) and follow Chapter 17.74 rezoning/attachment procedures. § 17.36.020, § 17.92.020, § 17.94.020.
• Prepare the required PD general development plan or specific development plan where the overlay requires PD. § 17.36.030–040.
• For AHO/BRHO: document compliance with below‑market‑rate unit percentages and affordability controls and prepare any in‑lieu fee calculations or agreements. § 17.92.040, § 17.94.040.
• If seeking incentives (parking reductions, density bonuses), prepare justification and be ready to negotiate a development agreement and/or conditions of approval. § 17.37.050–060.
• Provide site plans showing compliance with applicable development standards or PD modifications (setbacks, coverage, height) and address design review and landscape/screening as required. § 17.36.130, § 17.58.050. (See Foster City Development Standards and Foster City Landscaping and Screening.)
• Confirm parking calculations and any overlay parking exceptions with the community development director; consult Chapter 17.62 as modified by the overlay. § 17.36.060, § 17.37.030(H).

Risks & Ambiguities

Plain‑English summary

Foster City’s overlays (called combining districts in Title 17) are additional zoning layers that let the city and developers tailor rules for special projects — most commonly for affordable housing, senior housing, planned developments, or holding land for future development. Each overlay chapter spells out what it changes (for example: required affordable unit percentages, parking reductions, or ministerial review), so always check the specific overlay chapter (for example 17.37, 17.92, 17.94, 17.36) and confirm whether the overlay already covers your parcel or must be applied for.

Source References

• Foster City Municipal Code, Title 17, Chapter 17.36 PD — Planned Development Combining District, § 17.36.010–§ 17.36.140.
• Foster City Municipal Code, Title 17, Chapter 17.37 Senior Housing Overlay District, § 17.37.010–§ 17.37.070.
• Foster City Municipal Code, Title 17, Chapter 17.38 X Future Development Combining District, § 17.38.010–§ 17.38.040.
• Foster City Municipal Code, Title 17, Chapter 17.92 Affordable Housing Overlay Combining District, § 17.92.010–§ 17.92.040.
• Foster City Municipal Code, Title 17, Chapter 17.94 By‑Right Housing Overlay Combining District, § 17.94.010–§ 17.94.050.
• Foster City Municipal Code, general combining district designations and rules, § 17.10.020–§ 17.10.040.
• Foster City Municipal Code, design review standards and required findings, § 17.58.050–§ 17.58.060.
• For parking cross‑references see Chapter 17.62 and PD/overlay parking modifications in § 17.36.060 and overlay chapters.

Retrieved passages

• Foster City Zoning Code (chapter is) High relevance show source text
• Foster City Zoning Code (Chapter 17.36) High relevance show source text
• Foster City Zoning Code (Section 17.90.050) High relevance show source text
• Foster City Zoning Code (§ 1) High relevance show source text
• Foster City Zoning Code (chapter shall) High relevance show source text
• Foster City Zoning Code (§ 2) High relevance show source text
• Foster City Zoning Code (§ 1) High relevance show source text
• Foster City Zoning Code (§ 1) High relevance show source text

Cited sections

• Foster City Municipal Code, Title 17, Chapter **17.36 PD — Planned Development Combining District**, **§ 17.36.010–§ 17.36.140**. (Title 17)
• Foster City Municipal Code, Title 17, Chapter **17.37 Senior Housing Overlay District**, **§ 17.37.010–§ 17.37.070**. (Title 17)
• Foster City Municipal Code, Title 17, Chapter **17.38 X Future Development Combining District**, **§ 17.38.010–§ 17.38.040**. (Title 17)
• Foster City Municipal Code, Title 17, Chapter **17.92 Affordable Housing Overlay Combining District**, **§ 17.92.010–§ 17.92.040**. (Title 17)
• Foster City Municipal Code, Title 17, Chapter **17.94 By‑Right Housing Overlay Combining District**, **§ 17.94.010–§ 17.94.050**. (Title 17)
• Foster City Municipal Code, general combining district designations and rules, **§ 17.10.020–§ 17.10.040**. (§ 17.10.020)
• Foster City Municipal Code, design review standards and required findings, **§ 17.58.050–§ 17.58.060**. (§ 17.58.050)
• For parking cross‑references see Chapter **17.62** and PD/overlay parking modifications in **§ 17.36.060** and overlay chapters. (§ 17.36.060)
• FosterCity_ZoningCode.md

• Official Foster City code library