We pull a lot of permits at 1400 Highland. Manhattan Beach is not a hard city to work with, but the plan check is thorough, and the lots are tight. Most of our ADU clients here are working with a 5,400 sqft lot, a 30-ft height cap, and a 30% lot coverage limit that was already half-used by the primary house. That is the math you start with before you draw a single wall.
This post is about the permit side only. No construction costs, no square-foot estimates. Just what the city actually charges, how long plan check takes, and the conditions we see derail ADU submittals in the Sand Section, Tree Section, and El Porto. If you are thinking about adding a detached unit on your lot, read this before you hire anyone to draw plans.
What the city charges
The permit fee structure for an ADU in Manhattan Beach is published by the Building and Safety division. It comes out to a $2,400 base fee, and the $1,800 school fee is waived per state law on units under 750 sqft. That waiver is automatic for qualifying ADUs, you do not have to ask for it.
You will pay separately for any electrical panel work. The city charges $220 plus inspection for a panel upgrade, and almost every ADU we build here triggers one. A 200A service is typical when you are adding an electric kitchen and a heat-pump system.
Plan check fees are bundled into the base for ADUs, but if your scope creeps into remodel territory on the main house, the remodel fee schedule kicks in separately. Keep the scopes clean on paper.
Plan-check timeline
The city's typical plan check for an ADU runs 6 to 10 weeks for first review. Expedited review is available, and we use it on projects with tight occupancy deadlines, but it does not skip corrections. You still get red marks, you just get them faster.
Our overall ADU timeline, from design kickoff to final inspection, runs 16 to 28 weeks. Plan check is one slice of that. Design and engineering coordination is another 4 to 8 weeks before you even submit. Construction is the rest.
The Building and Safety counter is open Mon through Thu, 7:30am to 5:30pm, with alternate Fridays. Plan ahead if you need an in-person meeting. The phone is (310) 802-5500.
Code references that matter
Three code citations drive every ADU we permit in this city.
Gov Code 65852.2 is the state ADU law. Local ordinances cannot impose stricter standards than the state floor. That matters in Manhattan Beach because the city's view-equity ordinance and 30% lot coverage rules still apply to the primary structure, but the ADU has its own state-protected envelope rules.
Title 24 Part 6 applies fully to detached ADUs. Energy compliance is not optional, and the coastal climate zone affects your glazing and HVAC sizing. We spec mini-split heat pumps on almost every unit because they hit the numbers without drama.
AB 1033, passed in 2024, lets owners sell ADUs as condos separately from the primary residence in cities that opt in. Manhattan Beach has not opted in as of this writing, but it is worth tracking if you are building with a long-term exit in mind.
The gotchas that stall ADU submittals here
The sewer lateral is the one that surprises people. Older South Bay homes often have a 3-inch cast-iron lateral that is undersized for the added fixtures from a second kitchen and bathroom. Plumbing plan check will flag this, and the fix is a full lateral replacement to the city main. That is trenching across your yard, sometimes across a driveway.
Setbacks are another. State ADU law requires a minimum 4-ft setback from existing structures, regardless of local zoning. We see designers place units tight against the main house garage to maximize yard space, and then we have to redraw.
Fire sprinklers are conditional. If the primary residence has sprinklers, the ADU must also be sprinklered. Most pre-2011 Manhattan Beach homes do not have them, so this often does not apply, but check before you assume.
Edison panel capacity. We mentioned 200A above. Plan on it. The cost is not the issue, the timing is, because Edison schedules are unpredictable and the meter swap is on their calendar, not yours.
Coastal conditions that affect the design
Manhattan Beach has high salt-air corrosion west of Sepulveda. We spec marine-grade stainless fasteners and Galvalume metal where exposed. Hardie panel siding is the standard exterior material for coastal-rated wall assemblies.
Wind zone is Exposure D within 1 mile of the coast, which means increased framing and connector requirements per ASCE 7. Your structural engineer will spec heavier hold-downs and shear schedules than an inland project. The plan checker will verify these line by line.
The Hill Section has a design review process that applies above 26 ft, but most ADUs come in well under that. Sand Section and El Porto do not have HOA constraints in most cases.
May Gray and June Gloom compress the exterior finish window. We schedule paint and stain phases around that. It is not a permit issue, but it is a timeline issue, and it affects when you can hit your final inspection.
Why we self-perform
DECOMA holds CSLB A and B classifications. That means we self-perform structural framing and finish carpentry without a separate sub. One GC, one warranty, fewer handoffs. For an ADU under 1,200 sqft, we also handle design in-house, so you are not paying a separate architect retainer for a unit that has a fairly standard envelope.
You can see how this plays out on larger coastal builds like our Raymond Estate in Hermosa Beach. Same coastal conditions, same plan-check rigor, same approach.
FAQ
How long does ADU plan check take in Manhattan Beach? First review is 6 to 10 weeks. Total project timeline from design through final inspection runs 16 to 28 weeks.
What is the permit fee for an ADU? $2,400 base fee. The $1,800 school fee is waived per state law for qualifying units.
Do I need to upgrade my electrical panel? Usually yes. A 200A service is typical for a new electric kitchen plus heat-pump systems. The city charges $220 plus inspection for the panel permit.
Will my ADU need fire sprinklers? Only if the primary residence has them. Most pre-2011 homes do not.
Can I sell my ADU separately under AB 1033? Not yet in Manhattan Beach. The city has not opted in as of this writing.