Building an ADU in Hermosa Beach. Rules, costs, timeline.
What HBMC Chapter 17.21 (Ord. 26-1498) actually allows, how the California Coastal Zone overlay affects your permit, and what an all-in build costs on a Hermosa Beach lot in 2026.
What you can build — at a glance
Max ADU size
1,000 sqft (Class 2 local cap) · up to 1,200 sqft (Class 1 state-law pathway)
Detached height
16 ft default · 18 ft transit-proximate · up to 20 ft for pitch alignment
Attached height
Up to 25 ft (matches two-story primary)
Side & rear setbacks
4 ft
Units per SFR lot
Up to 3: conversion ADU + JADU + new detached ≤800 sqft (Gov. Code § 66323; HCD Handbook). Local HBMC says 1 ADU + 1 JADU — state law preempts.
Parking required
None on most lots (state-law exemptions apply)
Permit timeline
60 days · ministerial review, no hearing
AB 1033 separate sale
No — Hermosa Beach has not opted in. Sale separate from primary not permitted.
Detached (Class 2)Up to 1,000 sqft local cap
State-law (Class 1)Up to 1,200 sqft via Gov. Code pathway
AttachedUp to 25 ft · matches 2-story primary
Junior ADUUp to 500 sqft inside primary dwelling
ConversionExisting accessory structure to ADU
Per HBMC Chapter 17.21 (Ord. 26-1498, effective April 23, 2026) and Gov. Code §§ 66310–66342. Units-per-lot figure reflects the state-law stack confirmed by the HCD ADU Handbook (March 2026). Full citations in the sections below.
Most LA-area ADU pages on the public internet are wrong on
Hermosa Beach because they cite outdated 2022 or 2023
versions of the local ordinance. The current operative
rulebook is Hermosa Beach Municipal Code Chapter 17.21,
codified through Ord. 26-1498, adopted March 24, 2026 and
effective April 23, 2026. That ordinance brought HB into
alignment with current state law — notably the AB
1154 JADU owner-occupancy narrowing and SB 543
completeness-review tightening.
Every regulatory claim on this page is sourced from one of
three primary documents:
Local ordinance. Hermosa Beach Municipal
Code Chapter 17.21 (“Accessory Dwelling
Units”), codified through Ord. 26-1498, effective
April 23, 2026. The chapter contains definitions,
approval procedures, the Class 1 / Class 2 split, general
development standards, specific local standards, fees,
and legalization rules for pre-2020 unpermitted ADUs.
City guidance. City of Hermosa Beach
Community Development Department “Accessory
Dwelling Unit Ordinance Summary,” revised August 7,
2025. The handout summarizes Chapter 17.21 in a single
comparison table organized by ADU type (JADU, attached
ADU, detached ADU, conversion ADU, multi-family ADU).
Note that the handout predates Ord. 26-1498; the codified
chapter is the controlling source where they differ.
State law. California Government Code
§§ 66310–66342. The full ADU statute,
including amendments from SB 543, AB 1154 (effective
Jan 1, 2026), AB 1033, AB 2533, and SB 1211. State law
governs Class 1 ADUs entirely and sets the floor for
Class 2 ADUs.
Where state law and the local chapter ever conflict, state
law governs (Gov. Code § 66316). HB’s 2026
amendment brought Chapter 17.21 substantially into
alignment with current state law, but HCD has continuing
authority to review local ADU ordinances and reject any
provision that is more restrictive than state law allows.
Class 1 vs Class 2 ADUs under HBMC § 17.21.050
One of the cleanest things about Hermosa Beach’s
ordinance is how plainly it divides ADUs into two classes.
Knowing which class your project belongs to determines
which rules apply and what size, height, and design
options are on the table.
Class 1: Statutorily Regulated under Gov. Code § 66323
Class 1 ADUs are the state-protected, statutorily-exempt
ADUs created under Gov. Code § 66323. They are
approved with a building permit only — no separate
local ADU permit, no city design review, no public
hearing. HBMC § 17.21.050(A) identifies four Class 1
scenarios:
(A)(1) Converted on a single-family lot — one ADU plus one JADU within an existing or proposed single-family dwelling or an existing accessory structure, with up to 150 sqft of new area for ingress/egress.
(A)(2) Limited Detached on a single-family lot — one detached new-construction ADU at no more than 800 sqft and the applicable height limit. This is the state-protected detached pathway.
(A)(3) Converted on a multi-family lot — one or more ADUs within non-livable portions of an existing multi-family structure (storage rooms, basements, garages), up to 25% of the existing unit count.
(A)(4) Limited Detached on a multi-family lot — up to two detached ADUs on a proposed multi-family lot, or up to eight on an existing multi-family lot, subject to specific limits.
Class 1 ADUs are exempt from the local development
standards at § 17.21.070 — including the
850/1,000 sqft size caps, the strict architectural
conformance rules, the landscape screening requirements,
and the FAR/lot coverage limits. They follow only the
general requirements at § 17.21.060 (height, fire
sprinklers, rental term, owner-occupancy, deed restriction)
plus the state-law floor under Gov. Code § 66323.
Class 2: Locally Regulated under Gov. Code §§ 66314–66322
Class 2 ADUs are everything that doesn’t qualify
under Class 1 — typically attached ADUs that exceed
800 sqft, detached ADUs that exceed the § 66323
envelope, or any ADU on a property type where the
statutory exemption doesn’t apply. Class 2 ADUs are
still ministerial (no hearing, 60-day clock), but they are
subject to the full set of local standards at HBMC
§ 17.21.070: the size caps (850 studio/1BR, 1,000
2BR+), the architectural conformance requirements (match
primary dwelling materials, roof slope, colors), the
landscape screening rules, FAR limits, lot coverage
limits, and historical-property protections within 600
feet of a California Register property.
Which class fits your project?
For most single-family Hermosa Beach lots, the choice
comes down to size. If you want a 1BR or 2BR ADU at 800
sqft or smaller, Class 1 is almost always the right path.
You get the state-law protections and skip the
architectural conformance rules. If you want a larger
2BR or 3BR ADU, the math gets nuanced. The local cap is
1,000 sqft for 2+ BR units. Class 1 (A)(2) caps at 800
sqft for the state-protected pathway. Above 800 sqft, you
are in Class 2 with the full conformance rules. We work
through the class decision during the Backyard Review.
What you can build in Hermosa Beach
On a single-family lot in Hermosa Beach you may build one
ADU plus one JADU under the Class 1 conversion pathway
(HBMC § 17.21.050(A)(1)), or one detached new-construction
ADU under either Class 1 (A)(2) at 800 sqft or Class 2 at
up to 1,000 sqft. Multi-family lots can support more units
per § 17.21.050(A)(3) and (A)(4). The rules below
cover the most common case: a single-family detached or
attached ADU.
Size limits
Class 2 ADUs are capped at 850 sqft for
studio and 1-bedroom units and 1,000 sqft
for units with two or more bedrooms (HBMC §
17.21.070(A)(1)). An attached Class 2 ADU is further
limited to 50% of the primary dwelling’s floor area
(§ 17.21.070(A)(2)). Class 1 ADUs follow state law
— Gov. Code § 66321 allows up to 1,200 sqft for
2+ bedroom ADUs — and are exempt from the local
850/1,000 cap entirely.
Critical state-law floor: HBMC § 17.21.070(A)(3)
codifies the Gov. Code § 66321(b)(2) protection that
no FAR, front setback, minimum lot size, lot coverage, or
open-space requirement may prevent construction of an
800-sqft ADU. This protection applies to Class 2 ADUs and
is consequential on the smaller Hermosa Beach lots where
base-zone open-space and FAR rules would otherwise block
a buildable ADU.
Setbacks
Class 2 ADUs require 4-foot side and rear setbacks and a
25-foot front setback (HBMC § 17.21.070(C)(1)). No
setback is required for an ADU built in the same location
and dimensions as an existing structure
(§ 17.21.070(C)(2)). Class 1 ADUs follow the state-law
floor of 4 feet side/rear (Gov. Code § 66314(d)(7))
and use the primary dwelling’s front setback.
The Sunset
— 480 sqft one-bedroom at $239,000
all-inclusive. Under 750 sqft, so it qualifies for the
full Gov. Code § 66318 impact-fee exemption. Under
800 sqft, so it qualifies as a Class 1 ADU under HBMC
§ 17.21.050(A)(2) — meaning it skips the
local architectural and landscape conformance rules
entirely. For a residential lot north of the Pier or
east of PCH with buildable yard area, the Sunset is
the compact entry-level 1BR fit.
Maximum height
Detached ADUs are capped at 16 feet by
default (HBMC § 17.21.060(B)(1)). The height is
measured from existing legal grade or the lowest floor
(whichever is lower) to the peak of the structure
(§ 17.21.060(B)(5)). Two state-law upward exceptions
apply:
18 feet if the lot is within one-half mile walking distance of a major transit stop or high-quality transit corridor (HBMC § 17.21.060(B)(2); per PRC § 21155 definitions).
+2 feet (max 20 feet) if necessary to accommodate a roof pitch on the ADU aligned with the primary dwelling’s roof pitch (§ 17.21.060(B)(2)).
Attached ADUs may reach 25 feet or the
underlying zone’s height limit, whichever is lower
(§ 17.21.060(B)(4)). Notably, HBMC does NOT include
an above-detached-garage 26-foot allowance like Manhattan
Beach. A standalone two-story detached ADU is not
buildable in Hermosa Beach — the only path to
two-story ADU height is an attached ADU integrated into a
two-story primary residence.
Parking
HBMC § 17.21.070(G)(1) requires one off-street parking
space per ADU or per bedroom, whichever is less. Six
exemptions waive the requirement, matching the state-law
framework at Gov. Code § 66323(c):
(a) ADU is within one-half (½) mile walking distance of public transit;
(b) ADU is within an architecturally and historically significant historic district;
(c) ADU is part of the existing primary residence or accessory structure;
(d) on-street parking permits are required but not offered to ADU occupants;
(e) an established car-share vehicle stop is within one block of the ADU; or
(f) the ADU permit is submitted with a new SFR/MFD permit and the lot satisfies one of (c)–(e).
Most Hermosa Beach addresses qualify under at least one
exemption — the city’s compact footprint means
most lots fall inside the half-mile transit catchment.
Garage-conversion ADUs get a separate guarantee: HBMC
§ 17.21.070(G)(3) prohibits the city from requiring
replacement parking when an existing garage or covered
parking is demolished or converted. JADUs require no
parking under any circumstance.
The Wilshire
— 400 sqft studio at $219,000
all-inclusive. The smallest detached Signature Home in
the lineup, fit for the tighter Hermosa Beach lots
east of PCH or in the mid-block residential streets
that can accommodate a free-standing ADU within the
state-law 800-sqft envelope. Note that
HBMC § 17.21.070(H) requires Class 2 ADUs to match
the primary dwelling’s materials and roof slope
— the modern flat-roof variant shown here is
appropriate where the primary residence shares that
aesthetic; Class 1 ADUs (under 800 sqft) are exempt
from the architectural conformance rule.
Owner-occupancy — HB has codified AB 1154 properly
Owner-occupancy is not required for a standard ADU at a
single-family or multi-family dwelling in Hermosa Beach
(HBMC § 17.21.060(G)(1)). For a JADU, Hermosa Beach
is one of the few South Bay cities that has already
codified the AB 1154 narrowing directly into the
ordinance text. HBMC § 17.21.060(G)(2)(b)(I) exempts
the owner-occupancy requirement when the JADU has its own
separate sanitation facilities (a dedicated bathroom).
This is the cleanest implementation of the January 1, 2026
Gov. Code § 66333(b) amendment in the region. If your
JADU has its own bathroom, no owner-occupancy is required.
If the JADU shares a bathroom with the main house, the
owner must reside in either the primary dwelling or the
JADU as their legal domicile and permanent residence.
The second exception (§ 17.21.060(G)(2)(b)(II))
applies when the property is owned by a government agency,
land trust, or housing organization.
Short-term rentals: prohibited
HBMC § 17.21.060(D) prohibits any ADU or JADU rental
for a term shorter than 30 days. Unlike some neighboring
South Bay cities that permit STRs under a separate
registration ordinance, Hermosa Beach does not offer an
STR permit path for ADUs. The 30-day minimum is enforced
through the deed restriction recorded on the property
before certificate of occupancy is issued (§
17.21.060(H)). Plan around long-term rental as the only
legal rental option.
Impact fees
ADUs under 750 sqft of livable interior space are exempt
from all local impact fees (HBMC § 17.21.080(A)(1);
Gov. Code § 66318). ADUs at or above 750 sqft are
subject to impact fees charged proportionally to the size
of the ADU relative to the primary dwelling, not at the
full per-unit rate — HBMC § 17.21.080(A)(3)
codifies the proportional-charge formula. Education code
school fees do not apply (the ADU does not increase
assessable space by more than 500 sqft for purposes of
Education Code § 17620).
Utility connection fees are separate. JADUs and converted
ADUs on a single-family lot do not require a new utility
connection (HBMC § 17.21.080(B)(2)). New
detached-construction ADUs may require a separate utility
connection at the utility provider’s rates
(§ 17.21.080(B)(3)).
Permitting timeline
HBMC § 17.21.040(C) implements the state-law
ministerial review framework with notably tight deadlines.
The city must determine whether an application is complete
within 15 business days of submittal
(§ 17.21.040(C)(1)(a)); if no determination is made,
the application is deemed complete. The city must then
approve or deny the complete application within
60 days (§ 17.21.040(C)(3)); if not,
the application is deemed approved. These two deadlines
(matching Gov. Code § 66317) cap the realistic
in-house permit timeline at roughly 90–120 days for
a clean application. Coastal Zone projects add a separate
60-day CDP review on top of (and concurrent with) the
building permit clock.
ADUs in the Hermosa Beach Coastal Zone
Roughly half of Hermosa Beach lies inside the California
Coastal Zone — the regulatory boundary established
by the California Coastal Act of 1976 (Pub. Resources
Code § 30000 et seq.). The boundary runs inland
from the beach but does not cover the full city; whether
a specific property is inside or outside depends on its
exact address. We confirm Coastal Zone status during the
Backyard Review using the City’s official boundary
map, and we walk through the practical implications
before you commit to anything.
HB’s treatment of Coastal Zone ADUs is different
from neighboring Manhattan Beach. Where Manhattan
Beach’s published ADU Handout treats Coastal Zone
projects as subject to state ADU requirements only, HBMC
§ 17.21.040(C)(6) is explicit:
“Nothing in state ADU and JADU laws or this code
supersedes or in any way alters or lessens the effect or
application of the California Coastal Act of 1976.”
That means in Hermosa Beach, the local HBMC §
17.21.070 standards continue to apply in the Coastal Zone
AND a Coastal Development Permit (CDP) is required in
addition to the building permit. There is no “state
law only” bypass like Manhattan Beach offers.
The CDP carries its own 60-day deadline under HBMC
§ 17.21.040(C)(6)(b) and is reviewed concurrent with
the building permit. For a typical walk-street attached
ADU or garage conversion south of the Pier, the CDP
review is a documentation exercise — site plan,
elevations, drainage, view-corridor analysis. For a
detached ADU on a sloped, view-eligible lot on the
elevated blocks east of Hermosa Avenue, the CDP review
is materially more involved.
The CDP typically adds two to four months to the overall
permit timeline and roughly $5,000 to $15,000 in soft
costs (Coastal Commission processing fees, additional
plan-set work, view-corridor and drainage analysis). One
procedural protection: if HB does not have a fully
certified Local Coastal Program when an application is
received, the city must immediately notify the California
Coastal Commission of the application
(§ 17.21.040(C)(6)(c)).
Hermosa Beach’s architectural and landscape design rules
Hermosa Beach has some of the strictest architectural
conformance rules in the South Bay — and they only
apply to Class 2 ADUs. Class 1 ADUs under Gov. Code
§ 66323 are exempt entirely (HBMC §
17.21.070(H)(8) and (I)(5)). For projects that fall under
Class 2, the design rules shape almost every architectural
decision.
Match the primary dwelling
HBMC § 17.21.070(H) requires that a Class 2 ADU:
Materials and colors of exterior walls, roof, windows, and doors must match those of the primary dwelling (§ 17.21.070(H)(1)).
Roof slope must match the dominant slope of the primary dwelling — defined as the slope shared by the largest portion of the roof (§ 17.21.070(H)(2)).
Exterior lighting is limited to down-lights only (§ 17.21.070(H)(3)).
Independent exterior entrance apart from the primary dwelling’s entrance (§ 17.21.070(H)(4)).
Minimum interior dimensions of 10 feet wide in every direction, with a minimum 7-foot interior wall height (§ 17.21.070(H)(5)).
No direct line of sight
HBMC § 17.21.070(H)(6) prohibits any window or door
of the ADU from having a direct line of sight to an
adjoining residential property. Each window or door must
either be located where no direct line of sight exists,
or be screened with fencing, landscaping, or privacy
glass. For windows and doors within 30 feet of a property
line that is not a public right-of-way, additional
restrictions apply under § 17.21.070(H)(7): windows
must be clerestory (bottom of glass at least six feet
above finished floor), or both windows and doors must use
frosted or obscure glass.
Evergreen landscape screening
HBMC § 17.21.070(I) requires evergreen landscape
screening between the ADU and adjacent parcels. Specific
requirements:
At least one 15-gallon plant per 5 linear feet of exterior ADU wall, OR one 24" box-size plant per 10 linear feet of exterior wall (§ 17.21.070(I)(1)).
Plant specimens must be at least 6 feet tall when installed (or a 6-foot solid fence may be installed as an alternative, § 17.21.070(I)(2)).
All landscaping must be drought-tolerant (§ 17.21.070(I)(3)).
All plants must come from the city’s approved plant list (§ 17.21.070(I)(4)).
Historical-property buffer
HBMC § 17.21.070(J) imposes an additional rule: an
ADU within 600 feet of real property listed in the
California Register of Historic Resources must be located
so as not to be visible from any public right-of-way. This
rarely applies in HB but is worth confirming during the
Backyard Review if your property is adjacent to a
designated historic resource.
The design decision that follows
For most Hermosa Beach prospects, these rules push the
design conversation toward two questions. First: does
the primary dwelling already have a clean, definable
architectural style that the ADU can match without
compromise? Second: is the ADU project small enough to
fit under Class 1 and skip the conformance rules
entirely? Our Backyard Review walks through both in the
context of your specific lot and primary residence.
How California state law backs South Bay homeowners
HB’s 2026 ordinance is among the best-drafted ADU
chapters in the South Bay — but the state-law
backstops at Gov. Code §§ 66310–66342
still matter in several specific situations. The most
consequential protections every Hermosa Beach prospect
should know:
The 800-sqft / 16-ft / 4-ft floor. No
local rule — setbacks, lot coverage, open space,
FAR, percent-based caps — may prevent
construction of an 800-sqft ADU at 16 feet with 4 ft
side and rear setbacks (Gov. Code § 66321(b)(2);
codified locally at HBMC § 17.21.070(A)(3)).
Class 1 ADU bypass of local design rules.
ADUs that qualify under HBMC § 17.21.050(A) (Class
1, statutorily regulated under Gov. Code § 66323)
are exempt from the local development standards in
§ 17.21.070 entirely — including the
architectural conformance, landscape screening, and FAR
requirements. This is the single most consequential
class-selection lever in HB.
Ministerial-only review. ADU permits
are ministerial under all classes — no design
review, no neighborhood compatibility review, no
city-council vote (Gov. Code § 66317(a)(1); HBMC
§ 17.21.040(C)(2)).
Deemed-approved deadlines. HBMC §
17.21.040(C)(3) implements Gov. Code § 66317 with
teeth: if the city fails to act on a complete
application within 60 days, the application is deemed
approved by operation of law. Similarly, if the city
fails to issue a completeness determination within 15
business days, the application is deemed complete.
Parking exemption near transit. No
off-street parking may be required for an ADU within
one-half mile walking distance of public transit (Gov.
Code § 66323(c)(1); codified at HBMC §
17.21.070(G)(2)(a)).
Garage-conversion parking exemption.
When an ADU is created by converting an existing
garage, the city cannot require replacement parking
(Gov. Code § 66323(c)(2); codified at HBMC
§ 17.21.070(G)(3)).
Impact-fee exemption under 750 sqft.
ADUs under 750 sqft are exempt from all local impact
fees (Gov. Code § 66318; HBMC § 17.21.080(A)(1)).
AB 1154 JADU narrowing — already in the code.
HBMC § 17.21.060(G)(2)(b)(I) already implements
the January 1, 2026 narrowing of JADU owner-occupancy
to shared-bathroom cases only. No preemption analysis
needed; the code matches state law.
Pre-2020 legalization. Unpermitted ADUs
constructed before January 1, 2020 must be permitted
under HBMC § 17.21.090 (implementing Gov. Code
§ 66331) — the city cannot deny a
legalization permit on the grounds that the ADU
violates current standards, unless the violation
implicates H&S Code § 17920.3 substandard-building
criteria.
HOA preemption. Homeowner association
covenants that prohibit or unreasonably restrict ADUs
are unenforceable under Gov. Code § 66342.
The end-to-end permit process and timeline
ADU permits in Hermosa Beach are issued by the Community
Development Department, Planning and Building Divisions
(1315 Valley Drive). The end-to-end process for a clean
detached new-construction project on a standard
single-family lot takes roughly 5–7 months from
contract signing to issued building permit (longer in the
Coastal Zone), broken down as:
Weeks 1–4: Design and engineering. Site survey, architectural plan customization for your specific lot, structural engineering, Title 24 energy compliance, and (for Class 2 projects) matching of materials/colors/roof slope to the primary dwelling per HBMC § 17.21.070(H).
Weeks 5–6: Class selection and pre-submittal package. Confirm whether your project qualifies for Class 1 (skips architectural conformance) or falls under Class 2 (full local standards), assemble the appropriate submittal package, prepare the deed restriction for recordation.
Week 7: Submittal. Electronic submittal through the City of Hermosa Beach plan-check portal. State-law 15-business-day completeness determination clock starts (Gov. Code § 66317(a)(2); HBMC § 17.21.040(C)(1)(a)). For Coastal Zone projects, CDP application filed concurrent with building permit.
Weeks 8–15: Plan check. City plan-check review (60-day clock under HBMC § 17.21.040(C)(3)), plus corrections cycle and resubmittal. Typical project sees one to two correction cycles.
Weeks 12–20: Coastal Development Permit (Coastal Zone projects only). CDP review concurrent with building permit. View-corridor and drainage analysis on sloped or view-eligible lots may extend this.
Weeks 16–22: Permit issuance. Pay city permit and plan-check fees, pick up the approved permits. Deed restriction must be recorded with the LA County Recorder before certificate of occupancy.
We handle all permit processing, Coastal Development
Permit coordination, plan-check correspondence, and
agency clearances as part of every Signature Home project.
The deed restriction required at HBMC § 17.21.060(H)
is drafted to the City Attorney’s approved form and
recorded with LA County prior to final building inspection.
Signature Homes that fit Hermosa Beach lots
Three picks from the nine-model lineup for Hermosa Beach detached-ADU work — mid-block residential lots, elevated lots east of Hermosa Avenue, and east-of-PCH residential parcels. All three picks are single-story to fit the HBMC § 17.21.060(B)(1) 16-ft detached ADU cap. Walk-street properties south of the Pier are typically too tight for a detached Signature Home; the path there is an attached ADU or a garage conversion (both custom-tier work designed to the existing structure).
Single-story and attached projects only — none of the two-story portfolio builds fit Hermosa Beach's 16-ft detached cap (no above-garage exception like Manhattan Beach has). The work below maps cleanly onto what HB prospects typically need: a Craftsman-aesthetic single-story detached ADU, a 500-sqft one-bedroom multigenerational build at the state-protected envelope, a Spanish-style garage conversion for a coastal-aesthetic lot, and a turnkey rental ADU for the investor-owner segment.
The all-in cost of a Signature Home ADU in Hermosa Beach
is the same as in every other LA-area city we serve:
pricing does not vary by neighborhood. Our nine
architect-designed Signature Homes range from
$219,000 (Wilshire 400 sqft studio)
to $459,000 (Culver 1,200 sqft
three-bedroom two-story). The price includes architectural
design, structural engineering, Title 24 energy
compliance, all permit processing and plan-check
correspondence through to issued permit, all construction
labor and materials, interior finishes, cabinetry,
countertops, flooring, fixtures, appliances, and utility
connections for water, power, sewer, and gas.
What is not included in the Signature Home all-inclusive
price: City of Hermosa Beach permit and plan-check fees
(paid directly to the city, passed through at cost),
Coastal Development Permit fees for Coastal Zone projects,
any architectural finish upgrades required to match a
high-end primary residence under HBMC § 17.21.070(H)
beyond our standard finish library, and any site-specific
work outside the standard package (unusual grading on
sloped elevated lots east of Hermosa Avenue, retaining
walls, long utility runs, view-corridor analysis). We
identify and price all site-specific work in the
proposal before contract signing.
The Lincoln
— 1,000 sqft three-bedroom two-bath single-story,
$389,000 all-inclusive. The largest
single-story Signature Home in the lineup. At 1,000
sqft, it sits at the upper boundary of the HBMC Class 2
cap for 2+ BR ADUs (§ 17.21.070(A)(1)). The modern
farmhouse variant shown here fits the residential
character of HB’s mid-block streets — final
siding, color, and roof slope must match the primary
dwelling per § 17.21.070(H) unless the project
qualifies as a Class 1 ADU.
For a typical Hermosa Beach project, total cost to the
homeowner is the Signature Home all-inclusive price plus
$8,000–$13,000 in City of Hermosa Beach permit and
plan-check fees. Coastal Zone projects add
$5,000–$15,000 in CDP soft costs. The all-in number
for a typical Coastal Zone Hermosa Beach Signature Home
project lands at $232K–$487K depending on which
model you choose. Run your specific numbers on our
ADU ROI calculator
— the tool takes your lot, your model, your
expected rent, and your financing assumptions and returns
a year-by-year cashflow plus payback projection.
Why Hermosa Beach is a strong ADU market
Hermosa Beach is one of the highest rent-per-square-foot
ADU markets in LA County. Single-family home values in
2026 typically run $2.5M–$6M+ in the residential
blocks west of Pacific Coast Highway, with the supply of
new single-family inventory effectively frozen —
the city has 1.4 square miles of land and almost no
buildable greenfield.
An ADU on an existing Hermosa Beach lot captures a
meaningful slice of that scarcity premium without
triggering subdivision or larger redevelopment risk.
Rental returns are strong but constrained by the strict
30-day minimum (HBMC § 17.21.060(D) prohibits
short-term rentals entirely). One-bedroom ADUs in the
mid-block residential streets command long-term rents
of $2,800–$3,800 per month; two-bedroom ADUs on
the elevated blocks east of Hermosa Avenue command
$3,800–$5,200 per month; rare detached ADUs on
the walk-streets south of the Pier (where most lots are
too tight for free-standing construction) can clear
higher. The South Bay’s
tech-worker demographic — SpaceX, Northrop, Aerospace
Corp, ICANN, the El Segundo tech corridor — provides
consistent long-term tenant demand.
On the property-value side, a well-designed Class 1 ADU
(which avoids the architectural conformance overhead) at
800 sqft typically adds $400K–$700K to property
value — a meaningful multiple of the all-in
construction cost. A larger Class 2 ADU at 1,000 sqft
with matching primary-dwelling aesthetics can add even
more on the right elevated lot east of Hermosa Avenue.
The class-selection decision is one of the most
consequential financial levers in a Hermosa Beach ADU
project.
Hermosa Beach ADU questions, answered
The questions Hermosa Beach homeowners actually ask
before they start — with citations to HBMC Chapter
17.21 (Ord. 26-1498), the City of Hermosa Beach ADU
Ordinance Summary, and Gov. Code §§
66310–66342.
Does Hermosa Beach have its own ADU ordinance?
Yes. Hermosa Beach Municipal Code Chapter 17.21
governs ADUs and JADUs at the local level. The chapter
is one of the most current in the South Bay —
codified through Ord. 26-1498, adopted March 24, 2026
and effective April 23, 2026. HBMC § 17.21.050
establishes a clean two-class system: Class 1 ADUs
are statutorily regulated under Gov. Code §
66323 (the state-exempt small ADU pathway), and Class
2 ADUs are locally regulated under § 17.21.060
and § 17.21.070 with the city’s specific
size, design, and landscape requirements.
How big can my ADU be in Hermosa Beach?
It depends on the class. A Class 2 ADU is capped at
850 sqft for studio/1BR units and 1,000 sqft for
units with two or more bedrooms (HBMC §
17.21.070(A)(1)). An attached Class 2 ADU is further
capped at 50% of the primary dwelling’s floor
area. A Class 1 ADU under Gov. Code § 66323 is
not subject to these local caps — state law
allows up to 1,200 sqft for 2+ bedroom ADUs. All
pathways respect the state-law 800-sqft floor: no
local rule may prevent construction of an 800-sqft
ADU at 16 feet with 4-foot side and rear setbacks
(HBMC § 17.21.070(A)(3); Gov. Code §
66321(b)(2)). JADUs are capped at 500 sqft per HBMC
§ 17.21.030 and Gov. Code § 66333.
Can I build a two-story detached ADU in Hermosa Beach?
Not as a standalone detached ADU. HBMC §
17.21.060(B)(1) caps detached ADUs at 16 feet,
measured from existing legal grade to the peak of the
structure. The exceptions: (1) 18 feet if the lot is
within one-half mile walking distance of a major
transit stop or high-quality transit corridor
(§ 17.21.060(B)(2)); and (2) up to 20 feet if
necessary to accommodate a roof pitch aligned with
the primary dwelling. Hermosa Beach does NOT have an
above-garage 26-ft height allowance like Manhattan
Beach. The only path to two-story ADU living here is
an attached ADU integrated into a two-story primary
dwelling at up to 25 feet (§ 17.21.060(B)(4)).
Do I need to add a parking space for my ADU in Hermosa Beach?
Probably not. HBMC § 17.21.070(G)(1) requires
one off-street space per ADU or per bedroom,
whichever is less. But § 17.21.070(G)(2) waives
the requirement under six exemptions: within
one-half mile transit, within a historic district,
ADU within an existing primary or accessory
structure, on-street permits required but not
offered to ADU occupants, car-share vehicle within
one block, or submitted with a new SFR/MFD permit.
Most Hermosa Beach addresses qualify. Garage-conversion
ADUs are also exempt — § 17.21.070(G)(3)
prohibits the city from requiring replacement
parking. JADUs require no parking under any
circumstance.
Does Hermosa Beach require owner-occupancy for an ADU?
No, not for a standard ADU. HBMC § 17.21.060(G)(1)
states ADUs are not subject to an owner-occupancy
requirement. For a JADU, Hermosa Beach is one of the
few South Bay cities that has already codified the
AB 1154 narrowing directly into the ordinance:
§ 17.21.060(G)(2)(b)(I) exempts the
owner-occupancy requirement when the JADU has its
own separate sanitation facilities (a dedicated
bathroom). If your JADU shares a bathroom with the
primary dwelling, owner-occupancy is required; if
your JADU has its own bathroom, it is not. This
matches the January 1, 2026 amendment to Gov. Code
§ 66333(b).
What happens if my Hermosa Beach property is in the Coastal Zone?
Roughly half of Hermosa Beach lies inside the
California Coastal Zone — the boundary runs
inland from the beach but does not cover the full
city. Whether a specific property is inside or
outside depends on its exact address; we confirm
Coastal Zone status during the Backyard Review using
the City’s official boundary map. Unlike
Manhattan Beach (where the City Handout treats
Coastal Zone projects as exempt from local ADU
rules), HBMC § 17.21.040(C)(6) is explicit:
“Nothing in state ADU and JADU laws or this
code supersedes... the California Coastal Act of
1976.” That means the local HBMC §
17.21.070 standards continue to apply in the
Coastal Zone, AND a Coastal Development Permit
(CDP) is required in addition to the building
permit. The CDP must be approved or denied within
60 days under § 17.21.040(C)(6)(b); it
typically adds two to four months and roughly
$5,000 to $15,000 in soft costs.
What are the architectural design rules for ADUs in Hermosa Beach?
Hermosa Beach has some of the strictest architectural
conformance rules in the South Bay. HBMC §
17.21.070(H) requires that a Class 2 ADU’s
exterior wall materials, colors, windows, doors,
and roof slope must match those of the primary
dwelling. Exterior lighting is limited to down-lights
only. ADU windows and doors must not have a direct
line of sight to adjoining residential properties
— they must be screened by fencing, landscaping,
or privacy glass. Windows and doors within 30 feet
of a non-public-right-of-way property line must be
clerestory (≥6 feet above the floor) or use
frosted/obscure glass. The chapter also requires
evergreen landscape screening between the ADU and
adjacent parcels (§ 17.21.070(I)). Class 1 ADUs
approved under Gov. Code § 66323 are exempt
from these architectural and landscape rules.
Can I rent my Hermosa Beach ADU as a short-term rental?
No. HBMC § 17.21.060(D) prohibits any ADU or
JADU rental for a term shorter than 30 days —
regardless of when the ADU was created. Unlike some
neighboring cities that permit STRs under separate
registration, Hermosa Beach does not offer an STR
permit path for ADUs. The 30-day minimum is
enforced through the deed restriction recorded on
the property before certificate of occupancy is
issued (§ 17.21.060(H)). Plan around long-term
rental as the only legal rental option.
Fixed price in writingGuaranteed timelineCoastal Zone & CDP handled
Ready to build your ADU in Hermosa Beach?
We’ll check your lot, confirm whether your specific
address is inside the Coastal Zone, identify whether your
project qualifies for Class 1 (skips the architectural
conformance rules) or falls under Class 2, walk you
through which Signature Home fits your block, and give
you a fixed number — before you commit to anything.
15 minutes.
