Montclair · Building on your lot

Building on your lot in Montclair

Montclair sets its own accessory-structure limits for R-1 lots and its own home-business rules. The total size allowed for detached accessory structures rises with lot size.

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Key points

Accessory structures: Montclair limits R-1 accessory structures to 1 story or 15 ft; total detached floor area is 200–1,400 sq ft by lot size.
Home businesses: City rule: a home business may use 1 room of the home, no outside building or space, and no employees beyond resident family members.

Each rule below is marked Montclair code or CA state law and links to the section it comes from (checked October 2026). General information, not legal advice.

Sheds, garages and other accessory structures

Montclair code What Montclair's code adds
Maximum height	No more than 1 story or 15 feet. Applies: Accessory structures on R-1 single-family lots of any size; RV garages follow other rules. § 11.19.050 · code text Less than 6,000 square feet \| 200 square feet \| 1 \| 1 story or 15 feet
Size or lot coverage	No more than 200 square feet in total. Applies: R-1 lots under 6,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text Less than 6,000 square feet \| 200 square feet \| 1 \| 1 story or 15 feet No more than 400 square feet in total. Applies: R-1 lots of 6,001 to 9,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text 6,001—9,000 square feet \| 400 square feet \| 2 \| 1 story or 15 feet No more than 600 square feet in total. Applies: R-1 lots of 9,001 to 12,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text 9,001—12,000 square feet \| 600 square feet \| 2 \| 1 story or 15 feet No more than 800 square feet in total. Applies: R-1 lots of 12,001 to 15,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text 12,001—15,000 square feet \| 800 square feet \| 2 \| 1 story or 15 feet No more than 1,000 square feet in total. Applies: R-1 lots of 15,001 to 18,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text 15,001—18,000 square feet \| 1,000 square feet \| 2 \| 1 story or 15 feet No more than 1,200 square feet in total. Applies: R-1 lots of 18,001 to 20,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text 18,001—20,000 square feet \| 1,200 square feet \| 2 \| 1 story or 15 feet No more than 1,400 square feet in total. Applies: R-1 lots over 20,000 square feet; all detached accessory structures combined, including approved second units. § 11.19.050 · code text Over 20,000 square feet \| 1,400 square feet \| 2 \| 1 story or 15 feet

Running a business from home

Montclair code What Montclair's code adds
Space used	No more than 1 room in the home. § 11.58.030 · code text Not more than one room in the dwelling shall be employed for the home occupation; No building or space outside the main building may be used. § 11.58.030 · code text No building or space outside the main building shall used for home occupation purposes;
Customer visits	No more foot or vehicle traffic than is normal for the neighborhood. § 11.58.030 · code text The use shall not generate pedestrian or vehicular traffic beyond that normal to the neighborhood in which it is located;
Employees	No employees other than members of the resident family. § 11.58.030 · code text No employment of help other than the members of the resident family;

Lot splits under SB 9

Montclair code What Montclair's code adds
How the lot may be divided	Each new lot must be between 40% and 60% of the original lot. Applies: Original lot of at least 2,400 square feet. § 11.87.050 · code text Each of the resulting lots must be between 60 percent and 40 percent of the original lots.
Minimum new lot size	Each new lot must be at least 1,200 square feet. § 11.87.050 · code text The resulting lots must each be at least 1,200 SF.
Standards	Any standard that would block up to 2 units, or keep either unit under 800 square feet, is set aside. Applies: Standards that physically block up to 2 units or a unit of at least 800 square feet. § 11.87.130 · code text Any standard that would have the effect of physically precluding the construction of up to two units or that would physically preclude either of the two units from being at least 800 SF in floor area must be set aside. Waived in order until 2 units of 800 square feet fit: coverage, FAR, open space, tree preservation, articulation, second-floor setback. § 11.87.130 · code text 1. Lot Coverage; 2. Floor Area Ratio; 3. Open Space; 4. Tree Preservation; 5. Articulation; and 6. Second Floor Setback. Driveway access to a rear lot must be at least 12 feet wide with a prepared surface. Applies: Rear lots. § 11.87.120 · code text Driveway access to a rear lot shall be at least 12 feet wide, and constructed of a prepared surface such as concrete, brick/pavers, or asphalt. All dwelling sides must be within a 150-foot hose pull of the street or an onsite hydrant or standpipe. Applies: All dwellings on the site. § 11.87.120 · code text All sides of all dwellings on the site must be within a 150-foot hose-pull distance from either the public right-of-way or an onsite fire hydrant or standpipe. A paved fire access driveway at least 20 feet wide. Applies: New parcels with structures beyond a 150-foot hose pull. § 11.87.120 · code text A new parcel with structures exceeding a 150-foot hose-pull distance shall comply with Fire Marshal requirements, including, but not limited to, the provision of a minimum 20-foot wide paved access route/driveway for emergency Fire Department access.

Swimming pools

Montclair code What Montclair's code adds
Pool barrier	No horizontal openings over 4 inches. Applies: Fences or solid structures with vertical members. § 10.48.020 · code text For a fence or other solid structure having chief covering members constructed in a vertical direction, there shall be no openings in a horizontal direction of more than 4 inches No vertical openings over 4 inches. Applies: Fences or solid structures with horizontal members. § 10.48.020 · code text For a fence or other solid structure having their covering members constructed in a horizontal direction, there shall be no openings in a vertical direction of more than 4 inches.
Barrier height	At least 5 feet high. § 10.48.020 · code text Such fence or other solid structure shall be not less than 5 feet in height with no openings, ladders, or other means for access over the fence or structure (other than by doors or gates)
Gates	Self-closing and self-latching device at least 4 feet 6 inches above ground. Applies: All gates or doors through the enclosure; dwelling doors that form part of it are exempt. § 10.48.030 · code text All gates or doors opening through such enclosure shall be equipped with a self-closing and self-latching device not less than 4 feet, six 6 inches from the ground

Other Montclair rules on this

Montclair's code also has these chapters. We have not summarized their values on this page yet; read them in the library.

Parking RVs, oversized vehicles and trailers on the street (Ch. 8.38) — on public streets
RV garages on a single-family lot (§ 11.19.110) — single-family zones only
Permit for rooftop solar on a home (§ 10.20.030) — the next section covers EV charger permits

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

How big can a shed or accessory building be in Montclair?

Montclair limits R-1 accessory structures to 1 story or 15 ft; total detached floor area is 200–1,400 sq ft by lot size.

Can I run a business from my home in Montclair?

City rule: a home business may use 1 room of the home, no outside building or space, and no employees beyond resident family members.

Can I split my lot under SB 9 in Montclair?

Montclair's code: Each new lot must be between 40% and 60% of the original lot. (Original lot of at least 2,400 square feet.) (§ 11.87.050); Each new lot must be at least 1,200 square feet. (§ 11.87.050).

What are the pool fence and setback rules in Montclair?

Montclair's code: No horizontal openings over 4 inches. (Fences or solid structures with vertical members.) (§ 10.48.020); No vertical openings over 4 inches. (Fences or solid structures with horizontal members.) (§ 10.48.020).

General information, not legal advice.

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