Foster City — Development Standards

Last reviewed: July 2, 2026

Overview

This page summarizes the Foster City zoning ordinance rules that control how land may be developed — setbacks, height, lot coverage, density/FAR-related limits, and special standards (ADUs, SB 9, Planned Development). It focuses strictly on the local zoning / planning ordinance language — not Title 24 building code matters. Where the ordinance gives an explicit numeric standard I cite the controlling code section; where the ordinance text or uploaded extracts did not contain a clear numeric standard I state that it was Not found in retrieved materials. For topics that trigger other processes, see the city’s zoning overview, and for trade-specific items see parking, design review, overlay districts, ADUs, and the California Building Standards Code.

How to read this page

• Bolded terms are the exact district names or decision-relevant numeric standards you will see in the code.
• Each ordinance requirement is tied to the Foster City code section number and the uploaded ordinance file citation.
• If a numeric standard is not available in the retrieved materials I clearly mark it as Not found in retrieved materials — Verify with the jurisdiction for parcel‑specific answers.

District-by-district development standards

Note: each district subsection gives (A) purpose/typical permitted uses from the code, (B) where the rules apply, and (C) the key dimensional standards that the ordinance text shows (with the controlling §). If the numeric standard was not present in the retrieved excerpts I mark that explicitly.

R-1 / R-1/PD — Single‑family residence

• Purpose & typical uses: The R-1 district is the single‑family residential district (standard single‑family housing uses, accessory uses). SB 9 and two‑unit procedures in Foster City specifically apply to parcels in the R-1 and R-1/PD districts (see applicability). See § 17.79.020 .
• Where it applies: City parcels zoned R-1 or combined R-1/PD.
• Key numeric standards: Specific R‑1 area/bulk numeric rules (front/side/rear setbacks, maximum height, lot coverage or FAR) were Not found in retrieved materials for the R‑1 chapter excerpts in the uploaded materials. For SB 9 and ADU exceptions that affect R‑1 parcels, see § 17.79.060 and § 17.78 (ADU rules) below. Verify with the Community Development Department for parcel-specific R‑1 yard/coverage numbers. See § 17.79.020 for applicability of SB 9 to R-1 parcels .

R‑T — Townhouse / rowhouse multiple‑family

• Purpose & typical uses: The R‑T district regulates townhouse/rowhouse style residential development and related accessory uses. See Chapter heading 17.16 in the ordinance. The code requires compliance with the district’s area/bulk/yard/height table. See § 17.16.045 .
• Where it applies: Parcels mapped R‑T on the zoning map.
• Key numeric standards (table): front setback 5 ft, side/rear setbacks 0 ft / 10 ft (0 allowed except where adjacent to R‑1/R‑1/PD then 10 ft), maximum stories 3, maximum height 38 ft, maximum structural coverage 50%. See § 17.16.045 .

R‑3 — Medium‑density multiple‑family

• Purpose & typical uses: R‑3 allows multiple‑family residential development (apartments, condominiums) and accessory uses; all developments in R‑3 must follow the district’s area/bulk/yard/height rules. See Chapter 17.18 headings and design references § 17.18.010–.060 .
• Where it applies: Parcels zoned R‑3.
• Key numeric standards: The uploaded extracts include the R‑3 chapter headings but did not include a single clear, fully legible numeric table for every yard/height/coverage entry that can be relied upon verbatim here. For the official numeric table of front/side/rear setbacks, maximum height and permitted densities for R‑3, consult § 17.18.040 (Area, bulk, yard and height regulations) in the municipal code — Verify with the jurisdiction. See § 17.18.010 .

R‑4 — High‑density multiple‑family

• Purpose & typical uses: R‑4 is the high‑density multifamily district; permitted uses include multiple‑family housing and associated services. See Chapter 17.20 headings. See § 17.20.010–.060 .
• Where it applies: Parcels zoned R‑4.
• Key numeric standards: The ordinance includes an area/bulk/yard/height table for R‑4. The uploaded file includes the chapter and table location (Area, bulk, yard and height regulations) but the full numeric table is large and presented in the municipal code; pull the exact front/side/rear setbacks, maximum height and lot coverage for a given parcel from § 17.20.040. See § 17.20.040 .

C‑1 — Neighborhood Commercial

• Purpose & typical uses: The C‑1 neighborhood commercial district permits small‑scale commercial uses that serve nearby residents. See Chapter 17.24 (Permitted uses and area/bulk rules). See § 17.24.040 .
• Where it applies: parcels mapped C‑1.
• Key numeric standards (excerpted): The ordinance’s C‑1 table shows that small‑scale commercial frontage is allowed with close setbacks; the chapter states a typical maximum of 1 story and a maximum building height dimension in the table (see § 17.24.040). For exact front/side/rear setbacks and coverage percentages consult § 17.24.040 .

C‑2 — General Business

• Purpose & typical uses: C‑2 allows broader commercial business and mixed uses; where residential is included special rules apply. See Chapter 17.26 (C‑2) and the Area/Bulk table § 17.26.040 .
• Key numeric standards: The C‑2 chapter contains an area/bulk table and a clause that when a commercial zone abuts a residential zone no building shall be closer than twenty‑five feet to the residential zone. See § 17.26.040 .

C‑M / C‑O — Commercial Mix and Commercial Office

• Purpose & typical uses: C‑M targets mixed commercial uses and C‑O focuses on office uses; each has an area/bulk table and design requirements. See Chapters 17.28 (C‑M) and 17.22 (C‑O). See § 17.28.010–.070 and § 17.22.010–.050 .
• Key numeric standards: Each chapter includes a table for minimum lot area, setbacks, maximum heights and coverage. For parcel‑specific numbers consult § 17.28.040 and § 17.22.040 in the code. See § 17.28.010 and § 17.22.010 .

OSC — Open Space and Conservation

• Purpose & typical uses: OSC is limited to open‑space uses (parks, wildlife sanctuaries, water‑oriented uses) and only authorizes certain accessory or public facility buildings with special conditions. See § 17.34.010–.060 .
• Key numeric standards: The OSC chapter contains area/bulk, permitted uses and conditional uses in § 17.34.050; numeric standards in the excerpt were limited — see § 17.34.050 in the municipal code for details. See § 17.34.020 .

PF (Public Facilities) — Public and institutional facilities

• Purpose & typical uses: Public facilities such as schools, religious institutions and government uses; the code includes a special ADU/occupancy clause for PF parcels. See § 17.78.075 (standards applicable to PF zoning districts) .
• Key numeric standards: For ADU allowances on PF lands (e.g., up to four ADUs/JADUs for religious institutions or schools) and conversion rules, see § 17.78.075 .

PD (Planned Development Combining District)

• Purpose & typical uses: PD allows a site‑specific combination of uses with a graphic general development plan; it exists to provide flexibility in design consistent with the general plan. See § 17.36.010–.030 .
• Key numeric standards: A PD may, upon planning commission approval, waive many standard numeric requirements (minimum building site, yards, maximum coverage, heights, signs, etc.). See § 17.36.020 .

Code highlights you’ll use most (decision table)

Practical guidance / synthesis

• ADUs in Foster City are liberalized but subject to the local ADU chapter: expect 4 ft side/rear setbacks for new ADUs, conversion ADUs can often be done inside existing footprint without additional setbacks, and attached ADUs are capped at 25 ft and two stories (see § 17.78.070) .
• SB 9 (two‑unit / urban lot split) projects must meet the zone’s objective development standards but the code provides objective SB 9 rules: side/rear 4 ft, max height 25 ft, and minimum parking 1 space unless within transit proximity (see § 17.79.060) .
• Planned developments (PD) are the route if you need flexibility from numeric standards — the planning commission may waive many standards when approving a PD general development plan (see § 17.36.020) .
• Many district chapters defer to the citywide design chapter and parking chapter: always check Chapter 17.96 for design standards and Chapter 17.62 for parking before assuming any numeric standard will be accepted on its own. See district cross‑references in the code (multiple chapters reference these) .
• When a commercial or higher‑density zone abuts R‑1, additional setback buffers apply (for example, the C‑2 chapter requires commercial buildings to be at least 25 ft from an abutting residential zone) — check the abutting‑zone rule in the applicable chapter (e.g., § 17.26.040) .

Checklist

• Confirm the zoning district for the parcel (e.g., R‑1, R‑T, R‑3, R‑4, C‑1, C‑2, C‑M, C‑O, OSC, PF) and pull that chapter’s Area/Bulk table (see district chapter, e.g., § 17.16.045 for R‑T) .
• If proposing an ADU, confirm ADU type and comply with § 17.78 ADU provisions (side/rear 4 ft, attached max 25 ft, conversion rules) .
• If pursuing an SB 9 two‑unit or urban lot split on an R‑1 parcel, satisfy § 17.79.060 objective development standards (setbacks 4 ft, height 25 ft cap, parking rules) .
• Check whether your site is in a PD or an overlay that modifies standards (see overlay districts and § 17.36.020) .
• Prepare design submissions to comply with Chapter 17.96 and parking per Chapter 17.62; expect design review if the parcel or project triggers it (see design review) .
• If you need a front yard reduction or encroachment, check the procedures under § 17.54.080 (use permit or director discretion for limited encroachments) .
• Confirm any additional requirements in the applicable district chapter (e.g., minimum green area, separation to lagoon, or commercial‑residential buffers) — see the district’s Area/Bulk/Height section.

Risks & Ambiguities

Plain-English Summary

Foster City’s zoning chapters set the baseline development rules: district tables tell you minimum lot sizes, front/side/rear yard distances, maximum heights, and coverage; ADUs and SB 9 units have their own objective standards (ADUs: typically 4‑ft side/rear setbacks, attached ADUs ≤25 ft; SB 9: 4‑ft side/rear setbacks, ≤25 ft height and usually 1 parking space) — check the district chapter for parcel‑specific numbers and consult Community Development for any PD or overlay exceptions. See the ADU chapter (§ 17.78) and SB 9 chapter (§ 17.79) for the most frequently used exceptions and allowances .

Source References

• Foster City Municipal Code — ADU and multifamily ADU standards: § 17.78.070, § 17.78.075 .
• Foster City Municipal Code — SB 9 / two‑unit and urban lot split objective standards: § 17.79.010–.070 (see especially § 17.79.060) .
• Foster City Municipal Code — R‑T district area/bulk/yard/height rules: § 17.16.045 .
• Foster City Municipal Code — R‑3 / R‑4 district chapters (area/bulk/height): Chapter 17.18 and 17.20 (see district area/bulk sections such as § 17.18.040, § 17.20.040) .
• Foster City Municipal Code — C‑1 neighborhood commercial area/bulk: § 17.24.040 .
• Foster City Municipal Code — C‑2 general business area/bulk and residential adjacency buffer: § 17.26.040 .
• Foster City Municipal Code — Planned Development Combining District: § 17.36.010–.030 (waiver authority in § 17.36.020) .
• Foster City Municipal Code — Setback averaging, reductions and encroachments: § 17.54.070–.090 .
• Citywide references repeated in multiple district chapters: Design standards (Chapter 17.96) and Parking (Chapter 17.62) — district chapters cross‑reference these (see e.g., § 17.16.060, § 17.18.060, § 17.20.060) .

Retrieved passages

• CRC § 3 (§ 3) High relevance show source text
• CFC § 21155 (chapter shall) High relevance show source text
• Foster City Zoning Code (title report) High relevance show source text
• Foster City Zoning Code (§ 3) High relevance show source text
• CBC § 66314 (§ 66314) High relevance show source text
• Foster City Zoning Code (§ 4) High relevance show source text
• Foster City Zoning Code (chapter is) High relevance show source text
• Foster City Zoning Code (§ 2) High relevance show source text

Cited sections

• Foster City Municipal Code — ADU and multifamily ADU standards: **§ 17.78.070**, **§ 17.78.075** fileciteturn0file3turn0file0. (§ 17.78.070)
• Foster City Municipal Code — SB 9 / two‑unit and urban lot split objective standards: **§ 17.79.010–.070** (see especially **§ 17.79.060**) fileciteturn0file6turn0file2. (§ 17.79.010)
• Foster City Municipal Code — R‑T district area/bulk/yard/height rules: **§ 17.16.045** . (§ 17.16.045)
• Foster City Municipal Code — R‑3 / R‑4 district chapters (area/bulk/height): Chapter **17.18** and **17.20** (see district area/bulk sections such as **§ 17.18.040**, **§ 17.20.040**) fileciteturn0file15turn0file10. (§ 17.18.040)
• Foster City Municipal Code — C‑1 neighborhood commercial area/bulk: **§ 17.24.040** . (§ 17.24.040)
• Foster City Municipal Code — C‑2 general business area/bulk and residential adjacency buffer: **§ 17.26.040** . (§ 17.26.040)
• Foster City Municipal Code — Planned Development Combining District: **§ 17.36.010–.030** (waiver authority in **§ 17.36.020**) . (§ 17.36.010)
• Foster City Municipal Code — Setback averaging, reductions and encroachments: **§ 17.54.070–.090** . (§ 17.54.070)
• Citywide references repeated in multiple district chapters: Design standards (Chapter **17.96**) and Parking (Chapter **17.62**) — district chapters cross‑reference these (see e.g., **§ 17.16.060**, **§ 17.18.060**, **§ 17.20.060**) fileciteturn0file14turn0file10. (§ 17.16.060)
• FosterCity_ZoningCode.md

• Official Foster City code library