Big Bear Lake ADU rules

Maximum size

A Class 2 detached or attached ADU may be up to 850 sq ft with a studio or one bedroom, or 1,000 sq ft with two or more bedrooms. An attached ADU on a lot with an existing home is also limited to 50% of the home's floor area. Lot coverage (50% on a single-family lot, 60% on a multifamily lot), front setback, open space and the 50% rule cannot hold an ADU below 800 sq ft. A detached ADU up to 800 sq ft with 4 ft side and rear setbacks is allowed under state law as a Class 1 ADU.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(E)(1)(b), (G)(1), (G)(3), accessed 2026-11-03.

Setbacks

ADUs need 4 ft side and rear setbacks. A Class 2 ADU also needs a 15 ft front setback from a public right-of-way 40 ft wide or more, or 20 ft from a narrower one, unless that would hold the ADU below 800 sq ft. No setback is needed for a Class 2 ADU built in the same place and size as an existing structure.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(E)(1)(b), (G)(2), accessed 2026-11-03.

Local ADU rules

Big Bear Lake's ADU rules are in Development Code Section 17.25.210, last amended by Ordinance 2026-527 (February 11, 2026). Every ADU and JADU needs an ADU permit and a building permit, issued without a hearing. The City says within 15 business days whether an application is complete and acts on a complete application within 60 days. An ADU that does not meet the section's objective standards may still be allowed with a conditional use permit.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(D), (J), accessed 2026-11-03.

ADU types under state law (Class 1)

These are allowed under state law with only the section's general rules: one converted ADU and one JADU in a proposed or existing single-family home or an accessory structure (up to 150 sq ft added for entry and exit); one new detached ADU up to 800 sq ft with 4 ft side and rear setbacks, which may be combined with the converted ADU and JADU; converted ADUs in non-livable space of an existing multifamily building (at least one, up to 25% of the units); and up to two detached ADUs with a proposed multifamily building, or up to eight with an existing one, not more than the number of existing units. All other ADUs are Class 2 and follow the size, setback, parking and design rules below.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(E), accessed 2026-11-03.

Height

A detached ADU may be 16 ft. It may be 18 ft within a half mile walk of a major transit stop or high-quality transit corridor (plus 2 ft, up to 20 ft, for a roof pitch that matches the main home), or on a lot with a multifamily building of more than one story. An attached ADU may be 25 ft or the zone's limit for the main home, whichever is lower, and no more than two stories. Any ADU with a sloped roof of at least 2:12 pitch may be up to 30 ft if detached, or 40 ft if attached.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(F)(2), accessed 2026-11-03.

Parking

A Class 2 ADU needs one off-street space at least 9 ft by 19 ft, which may be in setback areas or tandem. No space is needed within a half mile walk of public transit, in a historic district, for an ADU that is part of the home or an accessory structure, where on-street permits are required but not offered, within one block of a car share stop, or when the ADU is filed with a new home or multifamily building. Garage, carport or uncovered spaces removed for an ADU do not have to be replaced. Class 1 ADUs (including a detached ADU up to 800 sq ft) and JADUs have no parking rule in this section.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(G)(6), accessed 2026-11-03.

Junior ADUs

A JADU may be up to 500 sq ft inside a proposed or existing single-family home (an attached garage counts), with an efficiency kitchen, and is allowed only on a lot zoned for single-family homes. If it shares a bathroom with the home it needs an inside entrance plus its own outside entrance. The owner must live in the home or the JADU only when the JADU shares a bathroom (not when the owner is a public agency, land trust or housing group). A recorded deed restriction is required before occupancy.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(C), (F)(1)(c), (F)(7)-(8), accessed 2026-11-03.

Design rules for Class 2 ADUs

A Class 2 ADU must match the main home's wall, roof, window and door materials and colors and its main roof slope; have its own outside entrance; be at least 10 ft wide inside in every direction with 7 ft ceilings; use shielded, downward lighting; avoid windows or doors with a direct view into a neighbor's lot (or screen them); use high or frosted windows within 30 ft of a side or rear line; and have evergreen screening or a 6 ft solid fence. These rules do not apply to Class 1 ADUs or JADUs.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(G)(7)-(8), accessed 2026-11-03.

Fees, utilities, sprinklers and rentals

No impact fees for a JADU or an ADU under 750 sq ft; larger ADUs pay in proportion to the main home's size. Converted ADUs and JADUs on a single-family lot need no separate utility connection or connection fee unless built with a new home; other ADUs need a separate connection for City utilities, with a fee in proportion to their size or plumbing fixtures. Fire sprinklers are needed only if the main home needs them. ADUs and JADUs may not be rented for less than 30 days or sold separately except as state law allows. Owners must give the City an expected rent with the building permit and report the rent each January.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(F)(3)-(5), (F)(9), (H), accessed 2026-11-03.

Septic systems

An ADU or JADU that connects to a septic system needs a percolation test from the last five years (ten years if the test was renewed) with the application.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(F)(6), accessed 2026-11-03.

Older unpermitted units

The City will not deny an ADU or JADU because of a nonconforming zoning condition, building code violation or unpermitted structure that is not a health and safety threat. A permit to legalize an ADU or JADU built before January 1, 2020 may not be denied for code violations unless a fix is needed for health and safety or the building is substandard.

Source: Big Bear Lake Municipal Code § 17.25.210 Accessory dwelling units (Municode), § 17.25.210(I), accessed 2026-11-03.