ADU Constructionin Loma Linda, CA
ADU construction in Loma Linda runs on state law: the permit is ministerial, with no hearing, and the City has 60 days after a complete application or it is deemed approved. The City allows one ADU plus one junior unit on a single-family lot, up to 850 or 1,000 square feet, with 4 foot side and rear setbacks.
Loma Linda is a small hospital-and-university city of about 7.8 square miles, and that shapes who builds an ADU here. The Census Bureau's ACS 2024 five-year estimates count 10,181 homes, 45.9 percent of them single-family detached and 42.5 percent in buildings of two or more units, and 62.1 percent of households rent. The median build year is 1984, so many lots hold an older house with room behind it. The City's Housing Element says it added an ADU permit type in 2020, adopted a state-consistent ordinance in 2021 and saw a substantial increase in applications.
We lead with state law because it sets the clocks, the size floors and the fee line. Then the page covers what the City allows, where a unit can sit, the Mission Road overlay, South Hills fire and fault rules, garages and sprinklers, and fees and rent rules. Code text came from GoCodebook's third-party mirror of the Municipal Code, so confirm each point with the City's ADU page and the Planning Division. Prices are on our ADU construction page, and the Loma Linda area page lists every trade we cover here.
What the City of Loma Linda says about an ADU
Where adu construction permits come from in Loma Linda: City of Loma Linda Community Development Department, Building and Safety Division.
- ADU sprinklers: Municipal Code 17.110.060(G) says an ADU or JADU must meet the Fire Code including any sprinkler requirement, but if the primary dwelling does not need sprinklers under Title 15, the ADU does not need them separately. Because Title 15 requires sprinklers in all new buildings, a new detached ADU is the case to confirm with the Fire Marshal. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
- ADU approval is ministerial: Chapter 17.110 (Ordinance 783, November 12, 2024) approves ADUs and JADUs without discretionary review when its standards are met, and no lot coverage, floor area, open space, minimum lot size or front setback rule may block an ADU up to 800 square feet and 16 feet high with 4 foot side and rear setbacks, or a JADU up to 500 square feet inside a single-family home. A planning permit and a building permit are both required and processed together, and the planning permit is issued within 60 days of a complete application unless the owner asks for a delay. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
- ADU sizes and types: one attached or detached ADU is allowed on a single-family lot, plus one JADU, with a maximum of 850 square feet for up to one bedroom and 1,000 square feet for two or more bedrooms, an attached ADU limited to 50 percent of the existing house floor area (up to those maximums), and no size limit for conversions of existing space apart from up to 150 square feet of new space for access. Multifamily lots can convert non-habitable space up to 25 percent of existing units or add up to eight detached ADUs. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
- ADU setbacks and height: new ADUs need at least 4 feet from side and rear lot lines, no part may be closer to the front lot line than the front plane of the house or 25 feet (whichever is less), conversions and same-footprint replacements need no added setback, and detached ADUs are limited to 16 feet (18 feet near major transit or on a multistory multifamily lot, with up to 2 more feet to match roof pitch); an attached ADU may be up to 25 feet or the zone limit, whichever is lower, and two stories. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
- ADU parking and design: one off-street space is required per ADU (tandem on a paved driveway allowed, none in the front setback unless the driveway is 20 feet deep), but none for JADUs, conversions, units within half a mile walking distance of a public bus stop, units in the Historic Mission Overlay District, or where a car-share is within a block; replaced garage spaces need not be replaced (except for a JADU made from an attached garage). The exterior must match the house's style, colors, roof pitch, windows and trim, every ADU needs its own exterior entrance, and no passageway is required. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
- ADU owner and rental rules: ADUs may be rented but not sold separately or rented for 30 days or less; for ADUs created on or after January 1, 2025 as part of a single-family dwelling the owner must live in the house or the ADU, JADUs always carry owner occupancy and a recorded deed restriction, and the application must include the projected annual rent. ADUs under 750 square feet pay no City impact fees, larger ones pay in proportion to the house size, and the owner pays water, sewer and other agency fees. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
- ADU fees and pre-approved plans: the November 2025 fee schedule lists ADU/JADU planning review at $805 for a new unit and $555 for a conversion. The City offers four pre-approved detached plans (462, 627, 738 and 983 square feet) for R-1 through R-4 lots with a single-family home that are not in a FEMA Flood Hazard Area; applicants contact the named engineer, sign a hold harmless form and apply on the portal, and any floor plan change means resubmittal to the City's plan checker.
- ADUs on historic parcels: an ADU on a National Register or California Register property, a local landmark or a contributor in the Historic Mission Overlay District must follow Chapters 17.80 and 17.82, must not change the street-facing facade, and any other exterior changes must exactly match the house and meet the Secretary of the Interior's Standards, with Mills Act contract terms applying where they exist. (Read in GoCodebook's third-party mirror of the Municipal Code, text as of 2026-10-04; the City's own code pages returned a Cloudflare 403, so confirm this ADU rule with the City.)
What does California law say about building an ADU in Loma Linda?
The City must treat an ADU as a building permit, not a hearing. Government Code sections 66310 to 66342 require ministerial approval, with objective standards only and no minimum lot size. Since January 1, 2026 the agency must say within 15 business days whether the application is complete, then approve or deny within 60 days, and silence after 60 days means the permit is deemed approved. If the City denies the application it must list every defect, and a written appeal gets a final answer within 60 business days. The text is on the Legislature's code site.
Loma Linda's Chapter 17.110, adopted as Ordinance 783 on November 12, 2024, says the same in local terms: ADUs and junior units are approved without discretionary review when the standards are met. A planning permit and a building permit are both required and are processed together, and the planning permit issues within 60 days of a complete application unless the owner asks for a delay. No lot coverage, floor area, open space, lot size or front setback rule may block an ADU of up to 800 square feet and 16 feet high with 4 foot side and rear setbacks, or a junior unit of up to 500 square feet inside a single-family home.
Our ADU versus JADU guide explains the junior unit, and the room addition versus ADU guide helps when you are choosing between the two.
How big can you build an ADU in Loma Linda, and how many fit on one lot?
A single-family lot gets one attached or detached ADU plus one junior unit. The City's maximum is 850 square feet for a unit with up to one bedroom and 1,000 square feet for two or more, an attached unit may not exceed 50 percent of the existing house, and a conversion of existing space has no size limit beyond up to 150 square feet of new space for access. State law lets a city cap a detached unit no lower than 850 square feet, or 1,000 with more than one bedroom, so Loma Linda's caps sit exactly at those floors.
Multifamily lots can convert non-habitable space such as storage or a garage, up to 25 percent of the existing units, or add up to eight detached ADUs. That matters in a city where 4,330 units sit in buildings of two or more, 1,096 of them in buildings of 50 units or more.
The City also offers four pre-approved detached plans of 462, 627, 738 and 983 square feet for R-1 through R-4 lots with a single-family home that are not in a FEMA Flood Hazard Area. You contact the named engineer, sign a hold harmless form and apply on the portal, and any floor plan change goes back to the City's plan checker.
Where can an ADU sit on the lot, and how many parking spaces does Loma Linda require?
A new unit needs at least 4 feet from the side and rear lot lines, and no part may sit closer to the front lot line than the front plane of the house or 25 feet, whichever is less. Conversions and same-footprint replacements need no added setback. Detached units top out at 16 feet, or 18 feet near major transit or on a multistory multifamily lot, with up to 2 more feet to match the roof pitch, while an attached unit may reach 25 feet or the zone limit, whichever is lower, and two stories.
Parking is one off-street space per ADU, tandem on a paved driveway allowed and none in the front setback unless the driveway is 20 feet deep. It is waived for junior units, conversions, units within half a mile walking distance of a public bus stop, units in the Historic Mission Overlay District and sites with a car-share within a block. A garage space that is replaced need not be rebuilt, except for a junior unit made from an attached garage.
Design rules are objective: the exterior must match the house's style, colors, roof pitch, windows and trim, and every ADU needs its own exterior entrance, though no passageway to the street is required. The standard R-1 numbers, a 7,200 square foot lot and 40 percent footprint coverage, do not stop a small state-protected unit.
Does an ADU in the Historic Mission Overlay or on a historic parcel need extra review?
It can. The Historic Mission Overlay District covers the Mission Road area between Redlands Boulevard, San Timoteo Creek, California Street and Mountain View Avenue, and its chapter reaches cultural resources more than 50 years old. An ADU on a National Register or California Register property, a local landmark or a contributor in the overlay must follow Chapters 17.80 and 17.82, must not change the street-facing facade, and must make any other exterior change match the house exactly and meet the Secretary of the Interior's Standards, with Mills Act contract terms applying where a contract exists.
A Certificate of Appropriateness costs $645 on the November 2025 fee schedule, and a certificate goes void if no building permit is pulled within 12 months, renewable once. Historic buildings are a small slice of the stock: 506 homes, 5.0 percent, date from 1939 or earlier and 1,334, 13.1 percent, from before 1960. The City's GIS parcel viewer shows lot data, zoning and land use, and Planning at (909) 799-2899 can say whether a parcel is a contributor.
Do the South Hills fire zones and the San Jacinto fault change where an ADU can go?
They can for lots in the southern third of the city. The Safety Element names the South Hills as the greatest fire hazard, and the State Fire Marshal's map for Loma Linda, dated March 24, 2025, shows Very High, High and Moderate zones. The City adopted those zones by Ordinance 785 on June 10, 2025: the stricter zone applies to a whole parcel, a zone cannot be lowered, and the City says it sends no notices to owners or insurers, so check the map and ask your insurer. Chapter 15.30 adopts the 2025 Wildland-Urban Interface Code, with the City's fire marshal as the code official.
The Safety Element also calls for a Fire Protection Plan on new development in High and Very High zones and for prohibiting new development or expansion in Very High zones, but those are General Plan policies, not code sections, and we could not confirm how they apply to a state-protected ADU. An Alquist-Priolo fault zone follows the San Jacinto Fault in the south, where a geologic report is required before approval and no habitable structure may sit across an active trace. Hillside areas of 10 percent grade or more need a slope analysis by a civil engineer.
Creek corridors matter too. The Safety Element names San Timoteo Creek and Mission Channel, the City follows the National Flood Insurance Program through Chapter 19.12, and the pre-approved plans are not offered in a Flood Hazard Area. We found no acreage for any fire zone, so the Fire Department, (909) 799-2850, is the source for your lot.
Can you convert a Loma Linda garage into an ADU, and does it need fire sprinklers?
Yes, and a conversion is the lightest route. It has no size limit beyond up to 150 square feet of new space for access, needs no added setback, carries no parking requirement and does not require replacing the garage spaces. Plans follow the City's checklist for ADUs and additions under 500 square feet: a site plan, foundation, floor and roof plans, four elevations, Title 24 energy calculations, wet-signed structural calculations and three 24 by 36 inch sets, now filed electronically, so ask the Building Division how the portal maps to that paper list.
Sprinklers are the open question. Municipal Code 17.110.060(G) says an ADU must meet the Fire Code, including any sprinkler requirement, but if the primary dwelling does not need sprinklers under Title 15, the ADU does not need them separately. State law points the same way, since an ADU cannot be forced to sprinkle when the main house is not required to. Title 15 requires sprinklers in all new buildings over 200 square feet, and Ordinance 793 of June 9, 2026 sharpened the rules for additions, so a new detached unit is the case to confirm with the Fire Marshal before design.
A fire final inspection comes before the building final, a Fire Department Access Plan is required for new construction before entitlement, and ADU permits carry a Fire review fee. Our garage conversion permit steps guide walks the process, though it was written for Los Angeles.
What do fees, rent rules and the build schedule look like for a Loma Linda ADU?
Planning review is $805 for a new ADU or junior unit and $555 for a conversion on the November 2025 fee schedule, with Building plan check and permit fees assessed separately on construction value. The City's ADU instructions add Fire review, Development Impact Fees, Redlands Unified School District fees and sewer capacity fees. Impact fees do not apply to a unit under 750 square feet, larger units pay in proportion to the house, and the owner pays water, sewer and other agency fees.
Rent rules need a call to the City. The code allows renting an ADU but not selling it separately or renting it for 30 days or less, and the application must state the projected annual rent. For ADUs created on or after January 1, 2025 as part of a single-family dwelling, the code text we read also requires the owner to live in the house or the ADU, while our reading of Government Code 66315 says a city may not impose owner occupancy on an ADU. The two differ, so ask Planning which governs before you plan to rent both units.
Our planning estimates, not City figures, are 4 to 10 weeks of design, the 15 business day check and 60 day decision, 2 to 6 weeks of site prep, then 3 to 5 months for a garage or 5 to 9 months for a detached unit. MDG Builders, CSLB #1040337, acts as the general contractor, and licensed subcontractors pour, frame and wire, each able to show a license number and certificate of insurance on request.
ADU photos from Loma Linda and nearby homes
Backyard cottages, garage conversions and utility work tied to Loma Linda, from older lots near Mission Road to hillside edges in the south and tract lots in the east. Tap a photo to enlarge it.
What adu construction costs around Loma Linda
On our ADU construction page the ranges run about $100,000 to $200,000 for a garage converted to a studio or one bedroom and about $200,000 to $400,000 for a new detached unit of 400 to 800 square feet. They rest on regional sources, none from Loma Linda. UC Berkeley researchers surveyed Los Angeles County households that finished or applied for an ADU in 2018 and 2019 and found a median of $100,000, with garage units at $90,000 and detached units at $180,000. The Terner Center estimated $148,000 for Los Angeles in 2020, Remodeling magazine's 2025 Cost vs. Value report prices a Los Angeles ADU at $178,536 and Angi's January 2026 Los Angeles page shows averages of $78,000 for an in-law suite and $130,000 for a guesthouse. A median owner-occupied home of $596,900, a South Hills fuel plan, a fault report, a raised floor near a creek or a long sewer run can each add a line a regional range misses. The ADU cost guide shows how the ranges are built. See ADU pages for Redlands, Colton, San Bernardino, Highland and Los Angeles. A bath inside the unit is on our Loma Linda bathroom page, windows on the Loma Linda window page and an attached room on the Loma Linda room addition page.
| What it covers | Typical range |
|---|---|
| Garage conversion to a studio or one bedroom | $100,000 to $200,000 |
| New detached ADU, 400 to 800 sq ft | $200,000 to $400,000 |
| UC Berkeley survey, Los Angeles County median, 2018 and 2019 projects | $100,000 overall. $90,000 garage. $180,000 detached. |
| Terner Center and Berkeley CCI, 2020 | $148,000 Los Angeles estimate. $167,000 statewide average. |
| Remodeling Cost vs. Value 2025, Los Angeles | $178,536 job cost |
| Electrical and plumbing, Angi Los Angeles, January 2026 | Electrical $2,600 to $7,800. plumbing $3,900 to $10,400. |
| City permit and plan check fees | Not priced here |
Loma Linda ADU questions, answered
How do I build an ADU in Loma Linda?
Start with a site visit and a survey, then file a planning permit and a building permit together on the City's online portal. Loma Linda approves ADUs ministerially, with no hearing, and issues the planning permit within 60 days of a complete application. The City also offers four pre-approved detached plans for lots outside a flood hazard area.
Do I need a permit to build an ADU in California?
Yes, a building permit, but not a hearing. State law requires ministerial approval using objective standards, and a missed 60 day deadline means deemed approval. In Loma Linda the planning permit and the building permit are processed together, and a historic parcel adds a Certificate of Appropriateness.
How long does it take to get an ADU permit?
Up to about 60 days after the City calls the application complete, and that completeness check takes up to 15 business days. Loma Linda's code says the planning permit issues within 60 days. The pages we read give no building plan check time for ADUs, so budget the statutory clocks plus time to answer comments.
How big can an ADU be in Loma Linda?
Up to 850 square feet with one bedroom or less and 1,000 square feet with two or more, with an attached unit capped at 50 percent of the existing house. Conversions have no size limit beyond 150 square feet of new access space, and a junior unit is capped at 500 square feet inside the home.
What is the difference between an ADU and a JADU?
An ADU is a full separate unit, attached or detached, with its own kitchen and bath, while a junior unit is capped at 500 square feet, sits inside the existing single-family home and may share sanitation with it. The City's code attaches owner occupancy and a recorded deed restriction to every junior unit, though state law since 2026 requires owner occupancy only when sanitation is shared.
Do I need to provide parking for my ADU in Loma Linda?
One off-street space, with many exceptions. None is required for junior units, conversions, sites within half a mile walking distance of a public bus stop, units in the Historic Mission Overlay District or where a car-share sits within a block. Tandem on a paved driveway counts, and replaced garage spaces need not be rebuilt.
Can I sell my ADU separately from my main house?
Generally no. Loma Linda's code bars separate sale, and state law makes exceptions only for a qualified low-income buyer through a nonprofit or under a city-adopted condominium ordinance. We did not find such an ordinance in the pages we read, so ask Planning whether the City has adopted one.
How much does it cost to convert a garage to an ADU?
We plan on about $100,000 to $200,000 for a garage converted to a studio or one bedroom, resting on Los Angeles area sources rather than a Loma Linda survey. The City's planning review adds $555 for a conversion on its November 2025 schedule, and building fees follow the value of the work.
Do Loma Linda ADUs need fire sprinklers?
Possibly not, but confirm a new detached unit first. The City's ADU chapter says an ADU needs sprinklers only if the primary dwelling does under Title 15, and state law agrees. Title 15 requires sprinklers in all new buildings over 200 square feet, so the Fire Marshal should answer in writing.
Do I have to live on the property to rent out my ADU?
That is a conflict to settle with the City. The code text we read requires the owner to live in the house or the ADU for units created on or after January 1, 2025, while our reading of state law bars owner occupancy rules on ADUs. For junior units the City's code requires the owner on site, and we confirm how that squares with the 2026 state change.
Tell us about your Loma Linda ADU
Share the neighborhood, whether the lot is flat, in the South Hills or near Mission Road, what you want to build or convert and who lives on the property, and the first visit starts with the permit route and the fire map question.