Building an ADU in Claremont. Rules, costs, timeline.
What CMC Chapter 16.333 actually allows after the City rewrote it from scratch in July 2026, how the Village and the historic districts shape a backyard build, and what an all-in project costs on a Claremont lot in 2026.
What you can build — at a glance
Reviewed by CALI ADU’s ADU specialists · August 2026
- Max ADU size
- 850–1,000 sqft 850 sqft with one bedroom or fewer, 1,000 sqft with more than one — exactly the state minimums. An attached ADU is also held to 50% of the existing house, but never below those floors. JADU: 500 sqft. No minimum size beyond an efficiency unit.
- Detached height
- 16 ft · single story Measured to the highest point of the structure from average ground level. 18 ft within a half-mile walk of a major transit stop, plus 2 ft to match the primary roof pitch; 18 ft on a multistory multifamily lot.
- Attached height
- 25 ft Or the height limit that applies to the primary dwelling, whichever is lower, and no more than two stories — written into the local chapter, matching the state floor.
- Side & rear setbacks
- 4 ft The state floor. Front setback follows your zone. No setback at all for an ADU converted from an existing structure, or rebuilt in the same place to the same dimensions.
- Units per SFR lot
- Up to 2 ADUs + 1 JADU The state stack: a conversion ADU + a JADU + a new detached ADU up to 800 sqft. The old one-unit-per-lot cap was repealed in July 2026; state-exempt units now sit outside the local standards entirely.
- Parking required
- 1 space · often waived Tandem and setback parking count. The state exemptions apply on top — transit proximity and the historic districts cover much of the city. No replacement parking for a converted garage; a JADU never needs a space.
- Permit timeline
- 60 days Ministerial approval by the Community Development Director — no hearing, no discretionary review, no neighbor sign-off. Completeness determined in 15 business days.
- Historic districts
- HC & Arbol Verde Historic Claremont and Arbol Verde AV1/AV2, plus any listed property. Parking drops to zero, but a garage demolition needs five days’ notice and a listed property needs a Certificate of Appropriateness.
- Detached Up to 1,000 sqft (2BR+) · 16 ft, single story
- Attached Same size caps, and no more than 50% of the house · up to 25 ft
- Garage conversion Attached or detached garage · no setback, no replacement parking
- Interior conversion Carved out of existing home space · no square-foot cap under § 66323(a)(1)
- Junior ADU Up to 500 sqft inside the single-family home, attached garage included
Per Claremont Municipal Code Ch. 16.333 as repealed and replaced by Ordinance No. 2026-02 (adopted July 14, 2026, effective 30 days after adoption) and Gov. Code §§ 66310–66342. Cross-checked against the HCD ADU Handbook (March 2026). Full citations in the sections below.
On this page
Can I build an ADU in Claremont?
Five things to know before you start
If you read nothing else here, read these. They are the five points that change the most projects in this city.
| What to know | Why it matters for your project |
|---|---|
| 1. The rulebook was replaced in July 2026 | Ordinance No. 2026-02 repealed and replaced CMC Chapter 16.333 in full. The Council adopted it on July 14, 2026 and it took effect 30 days later. It was drafted straight to the renumbered Government Code. Anything you read that predates it — including the City’s own ADU webpage and the codified chapter still showing on the code publisher’s site — may describe rules that no longer exist. |
| 2. The one-unit-per-lot cap is gone | The old chapter allowed “one accessory dwelling unit or one junior accessory dwelling unit” per lot. The new CMC § 16.333.040 permits ADUs and JADUs subject to Gov. Code §§ 66314 and 66328, and § 16.333.060(A) lifts state § 66323 units out of the local standards entirely. You no longer have to argue preemption to get the full stack. |
| 3. Detached still means single story | A standard detached ADU is capped at 16 feet (CMC § 16.333.060(B)(7)(a)(iii)) — the state floor. It rises to 18 feet on a transit-proximate or multistory-multifamily lot, and the 25-foot allowance applies to attached ADUs only. Plan the product accordingly, and see the two-story routes below. |
| 4. The design standards are real, and specific | Walls, windows, doors, roof pitch, and architectural style all have to read as the same house (CMC § 16.333.060(B)(12)). They are objective, so review stays ministerial — but they shape the drawings from the first sheet. An ADU consistent with the City’s Pre-Approved ADU Design Program is deemed architecturally compatible. |
| 5. Long-term tenancy for the units that matter | A state § 66323 ADU and a JADU may never be rented for 30 days or less (CMC §§ 16.333.060(B)(17), (C)(9)). State law requires that floor rather than merely allowing it (Gov. Code §§ 66323(e), 66333(g)). A larger ordinance ADU can take a short-term rental permit under CMC Chapter 16.110 — the one place Claremont is more permissive than most. |
How many units your lot can take
Everything in this section is grounded in CMC Chapter 16.333 as replaced by Ordinance No. 2026-02, and in Gov. Code § 66323; we won’t re-cite the local chapter on every line. The rewrite changed the answer here more than anywhere else on the page.
Under Gov. Code § 66323(a)(1)–(2) — confirmed by the HCD ADU Handbook (March 2026), p. 17 — a single-family lot may combine a conversion ADU carved from existing space in the house or an accessory structure, a JADU of up to 500 sqft inside the house, and a new detached ADU of up to 800 sqft with 4-foot setbacks. That is up to two ADUs plus a junior ADU. State law separately requires the City to allow at least one ordinance ADU under Gov. Code § 66314 — the larger 850- or 1,000-sqft unit the local development standards govern.
On a lot with an existing multifamily building the state counts apply: conversion ADUs in non-livable space, at least one and up to 25% of the existing unit count (Gov. Code § 66323(a)(3)(B)), and up to eight detached ADUs, capped at the number of existing units (Gov. Code § 66323(a)(4)(A)(ii)). JADUs remain a single-family product only, one per lot.
Owner-occupancy
You do not have to live on the property to build or rent an ADU. Gov. Code § 66315 forbids a city from requiring it, and Claremont’s chapter imposes no such condition. An investment build or a family-flex build works here the same way it does anywhere else in the county.
What can you build?
The numbers below come from CMC § 16.333.060(B), the track that governs a standard ordinance ADU, with state-law citations called out where the statute supplies or reinforces the local rule. Assume that anchor under each subsection unless we say otherwise. The parallel track at subsection (A) covers state-exempt units, and it is usually the shorter road on a constrained or character-controlled lot.
Which ADU type fits your property?
Claremont permits five types. On these lots the right one is usually decided by two things: whether the parcel sits in a historic district, and whether there is already a garage worth converting.
| If this sounds like you | Start with | What that means |
|---|---|---|
| You have a deep rear yard and want the most space, privacy, and rental value | Detached ADU | Up to 850 sqft with one bedroom or fewer, 1,000 sqft with more, single story at 16 ft, 4-ft side and rear setbacks, drawn to match the house. |
| Your lot is in Historic Claremont or Arbol Verde, or the parcel is tight, and you want the shortest path to a permit | The 800 sqft state-exempt unit | A new detached ADU of up to 800 sqft at 16 ft with 4-ft setbacks under Gov. Code § 66323(a)(2). CMC § 16.333.060(A) removes it from the local development standards entirely — the design standards, the interior-amenity specs, all of it — leaving only the 30-day rental floor and a percolation test on a septic lot. |
| You have a garage, attached or detached, that you rarely use | Garage conversion | Both are named as ADU locations. No setback for an in-place conversion, no replacement parking for the spaces you lose, and the demolition permit is issued alongside the ADU permit. |
| You want the unit under the existing roof, or the yard has to stay open | Interior conversion | Carve the ADU from existing space in the home. A conversion under Gov. Code § 66323(a)(1) has no square-foot cap and may add up to 150 sqft for ingress and egress. |
| You are housing a family member and want the lowest-cost path | Junior ADU (JADU) | Up to 500 sqft inside the single-family home — and the ordinance counts an attached garage as part of the residence, so a garage-to-JADU conversion is on the table. No parking may ever be required. Owner-occupancy applies only if it shares a bathroom with the house. |
Maximum size
| Standard | Limit |
|---|---|
| ADU, one bedroom or fewer | 850 sqft of interior livable space |
| ADU, more than one bedroom | 1,000 sqft of interior livable space |
| Attached ADU | The same caps, and no more than 50% of the existing primary dwelling — but never below 850/1,000 sqft (Gov. Code § 66321(b)(2)) |
| Conversion under Gov. Code § 66323(a)(1) | No square-foot cap; may expand up to 150 sqft for ingress and egress |
| State-exempt detached unit | 800 sqft, guaranteed regardless of lot coverage, floor-area ratio, open space, front setback, or minimum lot size (CMC § 16.333.060(B)(8); Gov. Code § 66321(b)(3)) |
| JADU | 500 sqft, inside the single-family home (Gov. Code § 66313(d)) |
| Minimum size | Whatever an efficiency unit requires — the old 150 sqft floor was repealed (Gov. Code § 66313(c)) |
Two changes here are worth naming, because they undo advice that was correct a year ago. The ordinance used to cap every ADU at two bedrooms; that cap is gone, which is why a three-bedroom unit at the 1,000 sqft ceiling is now a real option on a Claremont lot. And the 50% attached rule still trips people up: on a 1,600 sqft house, half computes to 800 — but Gov. Code § 66321(b)(2) puts a hard bottom under that math, so the 850 or 1,000 sqft floor controls instead.
Maximum height
| ADU type | Height limit |
|---|---|
| Detached, standard lot | 16 ft to the highest point of the structure, from average ground level — the state floor (Gov. Code § 66321(b)(4)(A)) |
| Detached, within ½ mile walking distance of a major transit stop or high-quality transit corridor | 18 ft, plus 2 ft to carry a roof pitch matching the main house (Gov. Code § 66321(b)(4)(B)) |
| Detached, on a lot with an existing or proposed multistory multifamily dwelling | 18 ft (Gov. Code § 66321(b)(4)(C)) |
| Attached ADU | 25 ft or the primary dwelling’s height limit, whichever is lower; no more than two stories (Gov. Code § 66321(b)(4)(D)) |
Setbacks and placement
Side and rear setbacks are 4 feet — the state floor in Gov. Code § 66314(d)(7), and a city may not require more of a conforming ADU. The front setback follows the underlying zone. An ADU converted from an existing structure, or rebuilt in the same location and to the same dimensions, needs no setback at all.
One placement rule catches people on narrow Claremont lots: an ADU may have no exterior entrance on any elevation less than 8 feet from a side property line, and an ADU sitting less than 8 feet off a side or rear line may have only clerestory windows, at least 6 feet above the floor, on those sides. There is a way out of the window rule — a solid wood fence or block wall at that property line, at least 5 feet 6 inches above the finish floor, plus screening landscaping. That exception is new in the 2026 rewrite and it saves a lot of designs.
Parking
| Requirement | Claremont rule |
|---|---|
| Standard ADU | One off-street space — permitted in a setback area or in tandem, unless the Director makes specific findings about topography or fire and life safety |
| Exemptions that zero out the space | Half a mile of public transit · an architecturally and historically significant district · an ADU within an existing primary or accessory structure · a car-share area within one block · an on-street permit area where the occupant is not offered a permit (Gov. Code § 66322) |
| Garage, carport, covered structure, or uncovered space demolished or converted for the ADU | No replacement parking may be required (Gov. Code § 66314(d)(11)) |
| JADU | None, ever — a city may not require parking for a JADU (Gov. Code § 66334(a)) |
Design standards, kitchens, and utilities
Claremont’s design standards are longer than most in the county. They are the reason a Claremont ADU looks like the house in front of it. Wall color, material, and texture; window types and doors; roof design, color, material, pitch, and texture — all substantially similar to the primary dwelling. The architectural style has to be the same, or compatible where no style can be identified. On a single-family lot the unit must hold the scale and look of a single-family home. It may not visually dominate the street. Mature trees are protected. A garage conversion seen from the street has to match the scale, materials, and landscaping of the house. And an exterior door may not face the same way as your front door where both are visible from the street, unless one sits 40 feet further back.
The chapter also specifies the kitchen. A unit of 500 sqft or less needs a 15-inch sink with a disposal and a 1.5-inch waste line, an opening for a 62-by-25-by-28-inch refrigerator, a two-element 120-volt stove, and 10 sqft of counter. Above 500 sqft it steps up to a 22-inch sink, a 69-by-30-by-29-inch refrigerator opening, a four-element stove, and 15 sqft of counter. Washer and dryer hookups go in a closet or laundry room, and shared laundry on the property now counts. These are easy to satisfy. They are also easy to fail on a set of drawings that was not written for Claremont.
On utilities, a conforming ADU is not treated as a new residential use for connection fees or capacity charges (CMC § 16.333.020(D)). Septic lots carry one extra item. A state-exempt unit needs a percolation test filed with the application, completed within the last five years, or ten if it has been recertified. Any ADU on a private sewage system also needs sign-off from the local health officer.
Signature Homes that fit the 16-foot envelope
Single-story plans engineered to sit under the detached height cap in CMC § 16.333.060(B)(7) — gable and traditional profiles that sit comfortably behind a Craftsman or a bungalow. Fixed plan fees, transparent build estimates.
The Laurel Canyon
The Melrose
The Lincoln
Our two-story plans cannot be permitted in Claremont as drawn. They stand roughly 25 feet, and the 25-foot allowance in this chapter applies only to attached ADUs — we do not sell the two-story plans as attached units. That is a constraint on the stock plan, not on the project: a two-story plan can be modified to fit the 16- or 18-foot envelope, or we design a custom ADU from scratch ($9,990–$19,990 for design and permit processing, bid per project). The single-story plans permit as drawn, which is why they lead.
What an ADU costs in Claremont (2026)
Our Signature plans are fixed-price — architectural design and full permit processing included, the same number whether the lot is in the Village, College Heights, or the north foothills. Construction is separate: once your plans are permitted, you build it yourself, bring your own licensed contractor, or build with one of our vetted construction partners. The figures below are the estimated cost to build each model with an independent licensed general contractor.
| Model | Configuration | Size | Collection | Est. cost to build |
|---|---|---|---|---|
| The Wilshire | Studio / 1BA | 400 sqft | Single-story | $180K–$200K |
| The Sunset | 1BR/1BA | 480 sqft | Single-story | $200K–$215K |
| The Westwood | 1BR/1BA | 550 sqft | Single-story | $215K–$235K |
| The Laurel Canyon | 2BR/1BA | 660 sqft | Single-story | $240K–$265K |
| The Melrose | 2BR/2BA | 800 sqft | Single-story | $275K–$295K |
| The Lincoln | 3BR/2BA | 1,000 sqft | Single-story | $325K–$350K |
| The Fairfax | 2BR/1.5BA | 840 sqft | Two-story | $280K–$310K |
| The Venice | 2BR/2.5BA | 1,080 sqft | Two-story | $335K–$365K |
| The Culver | 3BR/2.5BA | 1,200 sqft | Two-story | $385K–$420K |
The two-story models are shown for reference. In Claremont the detached envelope is single story, so the Lincoln at 1,000 sqft is the ceiling as drawn — and it lands exactly on the ordinance’s more-than-one-bedroom cap. Until this July it would not have been permittable at all, because the chapter capped every ADU at two bedrooms. Custom work is priced per project, $9,990–$19,990 for design and permit processing.
City fees and pass-throughs
A conforming ADU is a ministerial permit, so there is no planning entitlement to buy. Beyond that, we are going to be careful here: the ordinance sets the ADU permit application fee by resolution of the City Council rather than writing a number into the code (CMC § 16.333.050(B)), and building-permit and plan-check fees are valuation-based against the City’s published schedule. We have not verified a current Claremont figure for this build, so we are not printing one. Pull the current schedule from the City, or we will price it against your actual construction valuation during your Backyard Review.
Development impact fees are the part state law settles. An ADU of 750 sqft or less pays none (Gov. Code § 66311.5(c)(1)), and CMC § 16.333.020(D) writes the rule into the chapter: a conforming ADU is not a new residential use for connection fees or capacity charges, except that a unit above 750 sqft of interior livable space takes proportionate impact fees under Gov. Code § 66311.5. A JADU of 500 sqft or less is exempt, and an ADU or JADU under 500 sqft is outside school impact fees entirely (Gov. Code § 66311.5(c)(3)).
One offset worth checking: the City promotes the CalHFA ADU Grant Program on its own ADU page — up to $40,000, income-qualified, reimbursing pre-development costs such as design, permits, soil tests, property survey, and site prep. Availability and funding rounds change, so confirm with CalHFA before you build a budget around it.
What it returns: renting your ADU
Long-term or mid-term tenancy, for the units most people build here. For a rent benchmark, the government figure is HUD’s Fair Market Rent for the Los Angeles–Long Beach–Glendale HUD Metro FMR Area, which covers Claremont. For FY 2026, as revised effective May 21, 2026: $2,079 for a studio, $2,328 for a one-bedroom, $2,903 for a two-bedroom, and $3,681 for a three-bedroom. Those are metro-wide figures spanning the full range of housing stock and unit ages, so treat them as a floor rather than a forecast. A college town supplies an unusually steady mid-term market on top of that — visiting faculty, graduate students, and staff at the Claremont Colleges, on the 30-day-plus tenancies the ordinance points you toward anyway. A local property manager can price your specific street.
HUD FMR figures: FY 2026 Fair Market Rents, Los Angeles–Long Beach–Glendale HUD Metro FMR Area, as revised effective May 21, 2026 (huduser.gov). Your ADU’s actual performance depends on finish level, lot, access, and the rental market at the time you lease it. For payback math keyed to your lot, use the ADU ROI calculator or the ADU calculator.
When an ADU isn’t the right move
Not every Claremont property is a good ADU candidate, and it is cheaper to learn that now than after you have paid for plans. Four situations where we would tell you to wait, pick a different unit type, or not build:
- You want a separate-sale exit. The City has not opted into AB 1033, so an ADU cannot be conveyed apart from the house, and the deed restriction recorded before your building permit issues says so. If a condominium-style exit is the plan, this is the wrong jurisdiction for it.
- Your numbers depend on nightly rental of the new unit. A state-exempt ADU and a JADU may never be rented for 30 days or less, and state law requires that floor rather than merely allowing it. A larger ordinance ADU can take a short-term rental permit under CMC Chapter 16.110, but that is a separate approval with its own rules — do not assume it.
- You need two stories of detached space exactly as our stock plans draw it. The detached envelope is 16 feet, 18 on a transit-proximate parcel. The honest routes are a single-story plan, a modified two-story plan, or a custom design — not a variance, which takes the project out of ministerial review entirely.
- Your house has an unusual or heavily altered elevation and the budget is tight. The design standards ask the ADU to match walls, windows, doors, roof pitch, and style. On a distinctive or listed property that is a real design cost. On those lots the 800-sqft state-exempt unit, which sits outside the local design standards under CMC § 16.333.060(A), is usually the better move than a larger ordinance ADU.
How long an ADU takes
Here is what the schedule actually looks like on a Signature plan.
| Phase | Duration | Notes |
|---|---|---|
| Signature plan preparation | ~2 weeks | Pre-engineered plan customized to your lot — siting, the design match to your home, mature-tree protection, the parking-exemption check |
| City completeness check | 15 business days | The Director determines completeness and notifies you in writing; the application is generally deemed complete if that written incompleteness determination does not arrive in the window (CMC § 16.333.050(C)(3); Gov. Code § 66317(a)(2)(A), (F)) |
| Ministerial approval cycle | 60 days to a decision | CMC § 16.333.050(C)(4) and Gov. Code § 66317(a)(3) require a written approval or denial within 60 days of a complete application, and an ADU that gets neither is deemed approved. Pre-engineered plans clear plan check in weeks, not months — it is a conformance review, not a from-scratch evaluation. |
| Construction | 4–6 months | By model size — the schedule is guaranteed in writing, with a daily delay penalty if the contracted finish date is missed |
| Total, start to finish | ~6–9 months | Signature plans only. Custom designs add bespoke design time and a longer plan check, because the City is reviewing the drawings for the first time. |
Two timing details specific to this chapter are worth knowing. The deemed-approved backstop covers ADUs but not JADUs — the ordinance says so plainly, and it matches state law. And the City may not issue a certificate of occupancy for the ADU before it issues one for the primary dwelling (CMC § 16.333.050(F); Gov. Code § 66328), which only matters if you are building both at once.
The rules that make Claremont different
A brand-new ordinance, written to the current code
Claremont has amended its ADU chapter three times in fifteen months, and the last amendment was a demolition. Ordinance No. 2026-02 repealed and replaced CMC Chapter 16.333 in full. The Planning Commission recommended it 5-0-2 on May 19, 2026, the Council took a first reading on June 23 and adopted it on July 14, and Section 8 made it effective 30 days later. Its opening section now says outright that where the chapter conflicts with state ADU law, state law prevails.
The practical effect is that most of the preemption arguments a Claremont homeowner needed a year ago have been retired. The flat 16-foot cap on every ADU, the plate-height tie to the primary dwelling, the ban on a unit over a garage, the one-ADU-or-one-JADU limit, the two-bedroom cap, the 150-square-foot minimum, and the business-permit condition in the deed restriction are all gone. JADU owner-occupancy now matches AB 1154 in the City’s own text. So does the JADU definition: an attached garage counts as part of the single-family residence, which makes a garage-to-JADU conversion a local path rather than a statutory one.
Historic Claremont, Arbol Verde, and listed properties
Claremont protects its architecture more actively than most cities this size, and the ADU chapter defines exactly what counts. An “architecturally and historically significant district” is the Historic Claremont (HC) zone under CMC Chapter 16.004, the Arbol Verde single-family zones AV1 and AV2 under CMC Chapter 16.019, any property listed on the National Register, the California Register, or Claremont’s own Register of Structures of Historic and Architectural Merit, and any further district the Council designates under CMC Chapter 16.302.
That designation cuts both ways, and the upside is larger than people expect. A lot inside one of those districts is exempt from the ADU parking requirement outright under Gov. Code § 66322 — no space, no tandem stall, no driveway rework. The costs are two procedural steps. First: before demolishing a detached garage that an ADU will replace, you must give written notice to adjacent owners and post a placard on the property at least five days beforehand. Outside a historic district there is no public noticing for an ADU at all. Second: where the ADU would affect a listed property, approval includes a Certificate of Appropriateness under CMC Chapter 16.302.
The Village, the Colleges, and what the market actually wants
Claremont is about 37,000 people at the eastern edge of the San Gabriel Valley. It is built around seven colleges and a walkable historic Village, on deep tree-canopied lots below the foothills. Two features shape ADU decisions here more than the zoning does. The first is transit. The Claremont Metrolink and Metro A Line station sits at the Village, which puts much of the older housing stock inside the half-mile radius. That radius does two things at once: it deletes the parking requirement, and it lifts the detached height tier from 16 feet to 18 plus a roof-pitch allowance.
The second is the tenant pool. A college town produces a steady stream of 30-day-plus renters who are not students in the dormitory sense: visiting faculty on one-semester appointments, postdocs, staff, and families in transition. That maps almost exactly onto what the ordinance allows. It is unusual. In most cities the rental restriction fights the local demand rather than matching it.
No separate-sale path
Ordinance No. 2026-02 kept the prohibition on conveying title to an ADU separately from the primary dwelling, and the deed restriction recorded before your building permit issues repeats it for the ADU and any JADU. AB 1033 lets a city adopt a local ordinance allowing condominium-style separate sale (Gov. Code § 66342), and Claremont has not adopted that opt-in. Among LA-area cities only a handful have — Santa Monica (SMMC § 9.31.026, 2025) and Culver City (CCMC § 17.400.096, 2026) among them. Build here for rental income, family housing, or long-term value.
How the permit process works
Because a conforming ADU is ministerial, there is no planning entitlement to win first. The path is an accessory dwelling unit permit plus a building permit and its trade permits, reviewed against CMC Chapter 16.333. If the plans comply, the application must be approved — the Director has no discretion to deny a conforming project. Before any building permit issues, the deed restriction under CMC § 16.333.070 is recorded against the title; that applies to every ADU and JADU, not only to junior units, and it is a routine recordation handled at permit clearance.
Which of the two tracks you file under matters more here than in most cities, because Claremont’s local standards are long. A state-exempt unit under CMC § 16.333.060(A) — a conversion, a JADU, or the 800-square-foot detached path — escapes the design standards, the prescriptive kitchen specifications, the entrance and clerestory-window rules, and the historic Certificate of Appropriateness. A standard ordinance ADU under subsection (B) gets more square footage, up to 850 or 1,000, and takes all of them. Picking the track before you draw is worth more than any expediting trick.
The appeal route is unusually short. An incompleteness determination or a denial is appealed directly to the City Council under CMC § 16.321.020, and the Council’s final determination is generally due within 60 days of receiving the appeal (Gov. Code § 66317(d)(2)). There is no intermediate commission step for an ADU permit denial, which is a meaningful difference from the revocation process further down the chapter.
The pre-approved plan program
The City publishes an Accessory Dwelling Units Pre-Approved Designs program, which is the local answer to the statewide pre-approval mandate of AB 1332 (Gov. Code § 65852.27), required to be running by January 1, 2025. Ordinance No. 2026-02 gave it teeth that most city programs do not have: CMC § 16.333.060(B)(12)(c) states that an ADU consistent with the Pre-Approved ADU Design Program is architecturally compatible with the primary dwelling. That turns the single most subjective judgment in the chapter into a checkbox.
CALI ADU does not participate in the program. Our Signature plans are individually permitted on your lot and adapted to what these parcels actually present: the design match to your specific elevation, mature-tree protection, the 8-foot entrance and window rules on a narrow side yard, the historic overlay, and septic where it exists. If you want a standard plan built as filed on a simple lot, the City program is a real option and we will tell you so. If you want a design and permit partner with a fixed, transparent plan fee, that is us.
ADU questions, answered
The questions homeowners here actually ask before they start — with citations to CMC Chapter 16.333 (Ord. No. 2026-02) and Gov. Code §§ 66310–66342.
How many ADUs can I build on a single-family lot in Claremont?
Up to two ADUs plus a junior ADU. Ordinance No. 2026-02 repealed the old one-unit-per-lot cap: CMC § 16.333.040 now permits ADUs and JADUs on any lot zoned for residential use, subject to Gov. Code §§ 66314 and 66328, and CMC § 16.333.060(A) exempts state § 66323 units from the local development standards outright.
Gov. Code § 66323(a)(1)–(2) lets a single-family lot combine one ADU converted from existing space in the house or an accessory structure, one JADU of up to 500 square feet inside the house, and one new detached ADU of up to 800 square feet. The HCD ADU Handbook (March 2026, p. 17) confirms that stack. State law separately requires the City to allow at least one ordinance ADU under Gov. Code § 66314 — the larger unit CMC § 16.333.060(B) governs.
How big can an ADU be in Claremont?
Per CMC § 16.333.060(B)(5), the interior livable space of an ADU may reach 850 square feet with one bedroom or fewer, or 1,000 square feet with more than one bedroom. An attached ADU is separately held to 50% of the existing primary dwelling — but Gov. Code § 66321(b)(2) puts a hard floor under that percentage, so an attached ADU can never be cut below 850 or 1,000 square feet by bedroom count.
There is no minimum square footage any more: Ordinance No. 2026-02 replaced the old 150-square-foot floor with “sufficient for an efficiency unit” (CMC § 16.333.060(B)(4); Gov. Code § 66313(c)). A conversion ADU built under Gov. Code § 66323(a)(1) has no square-foot cap at all and may add up to 150 square feet for ingress and egress, and a JADU is capped at 500 square feet (CMC § 16.333.060(C)(4); Gov. Code § 66313(d)).
How tall can an ADU be in Claremont?
A standard detached ADU may reach 16 feet, measured to the highest point of the structure from the average ground elevation beneath it (CMC §§ 16.333.010, 16.333.060(B)(7)(a)(iii)) — the state floor in Gov. Code § 66321(b)(4)(A). Ordinance No. 2026-02 wrote the two state bonuses straight into the code: 18 feet plus 2 more feet to carry a roof pitch matching the main house, if the lot is within a half-mile walking distance of a major transit stop or high-quality transit corridor (Gov. Code § 66321(b)(4)(B)), and 18 feet on a lot with an existing or proposed multistory multifamily dwelling (Gov. Code § 66321(b)(4)(C)).
An attached ADU may reach 25 feet or the primary dwelling’s height limit, whichever is lower, and no more than two stories (Gov. Code § 66321(b)(4)(D)). The old flat 16-foot cap, the plate-height tie to the primary dwelling, and the ban on building an ADU over a garage were all repealed. For a detached backyard unit, Claremont is still a single-story market.
Do I need a parking space for an ADU in Claremont?
Often not. CMC § 16.333.060(B)(10) starts at one off-street space per ADU, expressly subject to the exceptions in Gov. Code § 66322 — among them a half-mile of public transit, an architecturally and historically significant district, an ADU created within an existing primary or accessory structure, a car-share area within one block, and an on-street permit area where the occupant is not offered a permit. Claremont’s Metrolink and Metro A Line station and its Historic Claremont and Arbol Verde districts put a lot of the city inside one of those.
The space may sit in a setback or in tandem unless the Community Development Director makes specific findings about topography or fire and life safety. Demolishing or converting a garage, carport, covered structure, or uncovered space never triggers replacement parking (CMC § 16.333.060(B)(11); Gov. Code § 66314(d)(11)), and no parking may be required for a JADU at all (CMC § 16.333.060(C)(7); Gov. Code § 66334(a)).
Does Claremont require the owner to live on the property?
Not for an ADU, ever — Gov. Code § 66315 forbids a city from requiring it, and Claremont’s chapter imposes no such condition. For a JADU, CMC § 16.333.060(C)(8) states the current rule correctly: owner-occupancy applies only where the JADU shares sanitation facilities with the existing structure, which is the narrowing AB 1154 made to Gov. Code § 66333(b) effective January 1, 2026.
Give the JADU its own bathroom and the requirement does not attach. The ordinance also carves out owners that are a governmental agency, land trust, or housing organization. This is one of the places where Ordinance No. 2026-02 caught the City’s code up to state law rather than leaving a preemption argument behind.
Can I rent a Claremont ADU on a short-term basis?
It depends on which unit you build, and the answer is more nuanced than most city pages allow. Under CMC § 16.333.060(B)(17), neither an ADU nor the primary dwelling may be rented for less than 30 days without a short-term rental permit under CMC Chapter 16.110 — so an ordinance ADU has a permitted path.
An ADU created under Gov. Code § 66323 has none: it may not be rented for a term of 30 days or less, full stop, and neither may a JADU (CMC § 16.333.060(C)(9)). That is not a local choice. Gov. Code § 66323(e) requires a local agency to impose a rental term longer than 30 days on a § 66323 unit, and Gov. Code § 66333(g) does the same for JADUs. The recorded deed restriction repeats it as a 31-day floor (CMC § 16.333.070(B)).
Does my ADU have to match my house in Claremont?
Yes, closely. CMC § 16.333.060(B)(12) requires the color, material, and texture of the walls, window types, and doors to be substantially similar to the primary dwelling, the roof design, color, material, pitch, and texture to be substantially similar, and the architectural style to be the same — or architecturally compatible where no style can be identified. On a single-family lot the ADU must also hold the scale and appearance of a single-family residence.
Two placement rules follow from it: an ADU may have no exterior entrance on an elevation less than 8 feet from a side property line, and an ADU with less than an 8-foot side or rear setback may have only clerestory windows at least 6 feet above the floor on those sides — unless there is a solid wood fence or block wall at that property line at least 5 feet 6 inches above the finish floor, plus additional screening landscaping. These are objective standards a plan checker applies, so review stays ministerial under Gov. Code § 66317. A design standard also cannot be used to block the 800-square-foot ADU with 4-foot setbacks that CMC § 16.333.060(B)(8) and Gov. Code § 66321(b)(3) both protect.
I own a home in a Claremont historic district — what changes?
Three things, and one of them works in your favor. CMC § 16.333.010 defines an architecturally and historically significant district as the Historic Claremont (HC) zone under CMC Chapter 16.004, the Arbol Verde single-family zones (AV1 and AV2) under CMC Chapter 16.019, any property listed on the National Register, the California Register, or Claremont’s own Register of Structures of Historic and Architectural Merit, and any further district the City Council designates under CMC Chapter 16.302.
The benefit: a lot in one of those districts is exempt from the ADU parking requirement entirely (Gov. Code § 66322). The two costs: before demolishing a detached garage that an ADU will replace, you must give written notice to adjacent owners and post a placard on the property at least five days beforehand (CMC § 16.333.050(D)), and where the ADU would affect a listed property, approval includes preparing a Certificate of Appropriateness under CMC Chapter 16.302 (CMC § 16.333.060(B)(12)(j)). Note that a state § 66323 unit is not subject to CMC § 16.333.060 at all, apart from the rental term and a percolation test on a septic lot (CMC § 16.333.060(A)).
Can I convert my garage into an ADU in Claremont?
Yes, and it is usually the shortest route. CMC § 16.333.060(B)(3) expressly lists attached garages, storage areas, and detached garages as ADU locations, and CMC § 16.333.060(B)(6)(b) requires no setback at all for an ADU converted from an existing structure or rebuilt in the same location and to the same dimensions. No replacement parking may be required for the spaces you lose (CMC § 16.333.060(B)(11); Gov. Code § 66314(d)(11)).
The demolition permit for a detached garage the ADU replaces is reviewed with the ADU application and issued at the same time (CMC § 16.333.060(B)(14)). A conversion carried out under Gov. Code § 66323(a)(1) has no square-foot cap and may add up to 150 square feet for ingress and egress. If the garage is visible from a public right-of-way, the design has to match the scale, materials, and landscaping of the house so the streetscape reads unchanged.
How long does an ADU permit take in Claremont?
The City must approve or deny a complete ADU application within 60 days, and the review is ministerial — no hearing, no discretionary review (CMC § 16.333.050(C)(2), (C)(4)(b); Gov. Code § 66317(a)(3)). Ordinance No. 2026-02 also wrote SB 543’s completeness rules into the chapter: written notice of the completeness determination generally within 15 business days, and an application generally deemed complete if the Director does not issue a written incompleteness determination in that window (CMC § 16.333.050(C)(3); Gov. Code § 66317(a)(2)(A), (F)).
An ADU is deemed approved if the City misses the 60-day clock; the ordinance notes that the deemed-approved path does not extend to JADUs. Appeals of an incompleteness determination or a denial go directly to the City Council, generally decided within 60 days (CMC §§ 16.333.050(C)(5), 16.321.020; Gov. Code § 66317(d)(2)). On a pre-engineered Signature plan, expect roughly 2 weeks of plan preparation, a permit cycle measured in weeks rather than months, then 4 to 6 months of construction — about 6 to 9 months start to finish. Custom designs run longer on both ends.
What does an ADU cost in Claremont?
Signature plan fees are fixed at $7,490 to $12,990, which includes architectural design and full permit processing. Building the unit with an independent licensed general contractor is estimated at roughly $180K–$420K across the lineup, depending on size.
City costs are separate. Claremont’s ADU permit fee is set by resolution of the City Council rather than written into the ordinance (CMC § 16.333.050(B)), and building-permit and plan-check fees are valuation-based — pull the current published schedule from the City before you budget, because we will not print a number we have not verified. Two Claremont-specific line items are worth pricing early: a Certificate of Appropriateness where the ADU affects a listed historic property, and a percolation test if the lot runs on an onsite wastewater treatment system.
Do I pay impact fees on a Claremont ADU?
Not below 750 square feet. An ADU of 750 square feet or less pays no development impact fees anywhere in California (Gov. Code § 66311.5(c)(1)), and CMC § 16.333.020(D) writes the line into the local chapter: a conforming ADU is not treated as a new residential use for connection fees or capacity charges, except that an ADU with more than 750 square feet of interior livable space is subject to proportionate impact fees under Gov. Code § 66311.5.
Proportionate means scaled to the primary dwelling’s size, not charged flat per unit. A JADU of 500 square feet or less is exempt as well, and an ADU or JADU under 500 square feet is not subject to school impact fees (Gov. Code § 66311.5, § 66311.5(c)(3)). Income-qualified homeowners may also be able to use the CalHFA ADU Grant Program, which the City promotes on its own ADU page — up to $40,000 reimbursing pre-development costs such as design, permits, soil tests, and site prep.
Can I sell my Claremont ADU separately from the main house?
No. CMC § 16.333.060(B)(18) prohibits conveying title to an ADU separately from the primary dwelling, and the deed restriction recorded before your building permit issues repeats it for both the ADU and any JADU (CMC § 16.333.070(A)).
AB 1033 lets a city adopt a local ordinance allowing condominium-style separate sale (Gov. Code § 66342), and Claremont has not adopted that opt-in — Ordinance No. 2026-02 kept the prohibition in place. Among LA-area cities only a handful have opted in, Santa Monica (SMMC § 9.31.026, 2025) and Culver City (CCMC § 17.400.096, 2026) among them. Build here for rental income, family housing, or long-term value, not for a condominium exit.
Does Claremont have pre-approved ADU plans?
Yes. The City publishes an Accessory Dwelling Units Pre-Approved Designs program on claremontca.gov, which is the local answer to the statewide pre-approval mandate of AB 1332 (Gov. Code § 65852.27, program required to be in place by January 1, 2025).
Ordinance No. 2026-02 gave it real weight: CMC § 16.333.060(B)(12)(c) states that an ADU consistent with the City’s Pre-Approved ADU Design Program is architecturally compatible with the primary dwelling, which converts the hardest judgment call in the chapter into a checkbox. A pre-approved plan moves faster through the counter but is built as filed. CALI ADU does not participate in the program: our Signature plans are individually permitted on your lot and adapted to its setbacks, grade, mature trees, and historic-district exposure.
Official sources
Where the local chapter and state law differ, state law sets a floor the city cannot drop below (Gov. Code § 66316) — and after the 2026 rewrite the chapter says so itself, in its opening section.
| Source | What it governs |
|---|---|
| Claremont Ordinance No. 2026-02 (signed PDF) (opens in a new tab) eCode360 (General Code) · adopted July 14, 2026 · effective 30 days after adoption · repeals and replaces CMC Ch. 16.333 in full | The operative local ordinance and the source for every CMC citation on this page: the size and height tiers, the 4-ft setbacks, parking, the design and interior-amenity standards, the JADU rules including owner-occupancy, the state-exempt track at § 16.333.060(A), the deed restriction, and the permit and appeal timelines. |
| Claremont Municipal Code Ch. 16.333 (codified) (opens in a new tab) eCode360 · still shows the superseded text (Ord. 19-07; 20-02; 2025-04) as of August 24, 2026 — check the “New Laws” table at the top for Ord. No. 2026-02 | The published code chapter, useful for confirming what changed. Until codification catches up, treat the signed ordinance above as controlling. |
| City of Claremont — Accessory Dwelling Units (opens in a new tab) claremontca.gov · Planning Division · includes the Pre-Approved Designs (opens in a new tab) program | The City’s ADU information, the permit application, the Pre-Approved Designs program, and the CalHFA ADU Grant note. Parts of this page still describe the pre-2026-02 rules — we flag that in the sections above. |
| California Government Code §§ 66310–66342 (opens in a new tab) California Legislative Information · renumbered from former § 65852.2 et seq. by SB 477, eff. March 25, 2024 | State ADU law — the floor every city must meet. Source for the 60-day ministerial clock, the owner-occupancy and parking preemptions, the height tiers, the 800 sqft entitlement, the impact-fee exemption, and the § 66323 unit stack. |
| HCD ADU Handbook (opens in a new tab) California Department of Housing and Community Development · updated March 2026 | The state’s official interpretation of ADU law, and the position that controls when a local rule reads more narrowly. The units-per-lot answer on this page comes from its worked example at p. 17. |
| HCD letter to Claremont (Dec. 5, 2025) (opens in a new tab) From HCD’s ordinance-review-letters registry, listed as “Accessory Dwelling Unit (ADU) Ordinance Updates” | HCD’s correspondence record with the City. We list it because the registry does; we have not read its contents and this page does not summarize them. Ordinance No. 2026-02 was adopted after it, and Section 7 of that ordinance requires the City to submit the new chapter to HCD for review within 60 days of adoption. |
Last verified against primary sources on August 24, 2026. California amends ADU law every January 1, and Claremont has amended this chapter three times in fifteen months. If you are reading this six months from now, confirm the current version before you commit to a design — or call us and we will confirm it for you.
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