Before You Build in Downey, CA: Permit & Rule Checklist (2026)

Downey requires a building permit before constructing most walls and fences under Municipal Code Section 8999.28(a). The only fence-specific exemption is for walls or fences up to 42 inches high; anything taller needs Building Official approval before work begins, alongside separate zoning limits on where and how tall a fence can be.

Downey exempts retaining walls up to four feet tall, measured from the bottom of the footing to the top of the wall, from a building permit under the city's Administrative Building and Housing Code. Taller walls, and any wall supporting a surcharge or impounding Class I, II or IIIA liquids regardless of height, need a permit and Building Official review before construction starts.

Residential fences in Downey top out at 42 inches in front and street-side setbacks, dropping to 30 inches within the corner cutback, and rise to seven feet on interior side and rear lines under Municipal Code Section 9520.08(l). Corner lots also carry a five-foot triangular setback for any fence over 42 inches near a driveway or alley.

California's Good Neighbor Fence Act (Civil Code 841) requires neighbors to share costs of boundary fences equally. Spite fences over 10 ft are a private nuisance under Civil Code 841.4.

Above-ground pools in Downey must meet the same CA Building Code barrier requirements as in-ground pools. Pools with walls under 60 inches require additional fencing to reach the minimum barrier height.

Pool fencing in Downey must meet California Building Code: 60-inch minimum height, self-closing/self-latching gates, plus one additional safety feature (cover, alarm, or self-closing doors).

Downey lets homeowners convert garages and other non-livable space into ADUs under § 9414.10(a)(3): on multifamily lots, up to 25% of existing units, but at least one, can come from converting garages, storage rooms, basements, or attics, while single-family conversions run through § 9414.08.

Downey allows up to two ADUs plus one JADU on single-family lots in the R-1, R-2, R-3, R-3-O, and M-U zones under § 9414.06 and § 9414.08, with size capped at 850-1,000 square feet, four-foot side/rear setbacks, and a 16-foot height limit for detached units.

Downey lets residents build tiny houses under Appendix BB of the 2025 California Residential Code, adopted by reference as the "Downey Building Code" in Municipal Code Section 8993. A tiny house still needs a full building permit reviewed by the Building and Safety Division and must meet the appendix's reduced ceiling-height, egress, loft and stair standards rather than standard single-family dwelling requirements.

Downey lets homeowners build a one-story detached shed, playhouse or similar accessory structure without a building permit if its floor area stays at or under 120 square feet. Larger sheds need a permit, and every detached accessory building must still meet the placement rules in Municipal Code Section 9534.22.

Downey Municipal Code Section 3306 amends California Fire Code 105.5.36 to require an operational permit before kindling any open burning or recreational fire on public or private ground, and bars issuing a private-property permit unless the applicant first notifies adjoining owners.

Downey Municipal Code Section 3311 caps every backyard fire pit or recreational fire at three feet in diameter and two feet in height, bans burning after 10 p.m. on weeknights and midnight on weekends, and forbids starting fires before 7 a.m. any day.

Removing a Downey street tree, City-owned or planted in the public right-of-way, requires a valid Public Works Department permit under Municipal Code § 7623, and only ten enumerated conditions, from disease and structural instability to power-line conflicts, justify removal. A denied request can be appealed to the Director under § 7624, whose decision is final.

Downey caps potable-water landscape irrigation to 7 p.m.-8 a.m., six minutes per irrigation-controller station per cycle, and two designated days a week (October-April) or three (May-September) under Downey Municipal Code § 7350(a). Odd-numbered addresses water Monday/Wednesday/Friday; even-numbered addresses water Tuesday/Thursday/Saturday. Hand-held hoses with shutoff nozzles, drip systems and repairs are exempt from the daily windows.

Downey's Urban Forest Management Plan governs street and median tree maintenance. The Director oversees all parkway tree planting, pruning, and removal. Property owners may not trim or remove street trees without authorization.