ADU Design & Permitting Cost - Plans, Permits & Build, One Fixed Price

Every project starts with

A free site visit, a check of what your lot allows and a written, line-item price.

Get your free estimate

How Much Does ADU Design & Permitting Cost in San Diego?

ADU design and permitting in San Diego typically costs between $12,000 and $35,000 when bundled as a single service package, with most homeowners landing around $18,000 to $24,000 for a standard detached unit. Standalone design work runs $8,000 to $15,000, while permitting alone ranges from $3,500 to $9,000 depending on your neighborhood’s specific review requirements and whether you need coastal, historical, or fire-zone approvals. Those figures cover the full design set, structural engineering, Title 24 energy calculations, and city submittal through final permit issuance.

We’re Lodgewick ADU Builders, the ADU company of the Kingswell family. We’ve been building accessory dwelling units, garage conversions, and home additions in San Diego since 2010, and we put every price in writing before any work begins. This guide gives you the real numbers we see across San Diego neighborhoods in 2026, so you can budget without having to sit through a sales pitch first.

If you’re just starting your research, our ADU Design & Permitting in San Diego page walks through the full process step by step. This page is purely about cost.

Key Takeaways

• Design and permitting for a San Diego ADU runs $12,000 to $35,000 combined; design-only averages $12,000, permitting-only averages $6,000.
• Prefab ADU packages from brands like Abodu or Cover often include design fees, bringing your bundled design-plus-permitting cost down to $8,000 to $15,000.
• San Diego’s ADU permit review typically takes 60 to 120 days for standard projects, and you can’t legally pour a foundation or pull electrical without an approved set of plans.
• City of San Diego fees alone (plan check, building permit, impact fees) usually total $6,000 to $12,000 for a detached unit under 800 sq ft.
• Lodgewick ADU San Diego provides a written price before any work starts, and a live person answers calls 24/7 at (619) 376-2760.

ADU Design & Permitting Cost Breakdown (2026)

Here are the line-item costs we see across San Diego in 2026. These are real ranges from projects in Clairemont, North Park, Chula Vista, El Cajon, and Oceanside, not national averages you’d find on a generic blog.

What moves the number up or down? A garage conversion (turning an existing garage into a JADU, or junior accessory dwelling unit) is nearly always the cheapest path because the foundation, framing, and roof already exist. You’re paying for design modifications, not from-scratch architecture. A detached two-story ADU with a hillside lot in Point Loma or a canyon-edge property in Rancho Peñasquitos adds structural complexity, taller foundation requirements, and sometimes geotechnical review, all of which push design and permitting toward and past that $30,000 mark.

Prefab manufacturers change the math. Companies like Abodu, Cover, and Dvele include stamped architectural plans in their unit price, so your standalone design fee drops to coordination work: $2,500 to $5,000 instead of $8,000 to $15,000. We work with Abodu, Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie products regularly, and we match the system to your lot and budget rather than forcing a square peg into a hillside.

What Affects ADU Design & Permitting Pricing in San Diego

• Your lot’s geology and slope. San Diego is not a flat city. Neighborhoods like Mission Hills, Kensington, and parts of La Mesa sit on canyons or slopes where a soils report and deeper foundation design are standard. A hillside ADU typically adds $3,000 to $8,000 in engineering and permitting complexity compared to a flat lot in Clairemont or Mira Mesa.
• Coastal zone and historical district overlays. If your home is west of I-5 or in a designated historic district (parts of Coronado, La Playa, Mission Hills, and Bankers Hill), you’re looking at extra review layers. Coastal Commission permits and historical review boards add $2,000 to $6,000 in consultant time and extend the permitting timeline by 2 to 6 months.
• Detached vs. attached vs. garage conversion. A JADU inside your existing home footprint is cheapest to design and permit, often $5,000 to $9,000 total for design work. A detached unit requires full architectural drawings, separate utility connections, and more involved plan check: that’s the $12,000 to $35,000 range.
• Fire zone requirements. Large portions of Scripps Ranch, Rancho Bernardo, and unincorporated East County sit in Very High Fire Hazard Severity Zones. If your property is in one, you’ll need fire-resistant materials specified in the plans, possibly sprinklers, and additional plan check scrutiny. Expect $1,500 to $4,000 in added design and permit costs.
• Utility connection distance. San Diego Gas & Electric (SDG&E) trenching and panel upgrades are not design fees, but they influence what your engineer draws. A detached ADU 80 feet from the main panel needs a more involved electrical design than one 15 feet away. Design modifications for long utility runs add $800 to $2,500.
• Whether you use a design-build firm or separate architect and general contractor. Splitting the work means paying two markups and coordinating two schedules. Bundling design, permitting, and construction through one company like ours removes handoff markups. It’s not uncommon for a separate-architect path to cost 15 to 20 percent more on the design and permitting phase alone.

How to Save on ADU Design & Permitting

Saving money on design and permitting is not about cutting corners. It’s about cutting rework. Every time a plan set goes back to the city for correction, you pay additional plan check fees (typically 35 to 50 percent of the original plan check cost) and lose weeks. The cheapest permit is the one approved on the first or second review cycle.

Practical ways to keep your costs in the lower half of the ranges above:

• Choose a garage conversion or JADU first. Converting an existing garage in a neighborhood like Normal Heights or City Heights often brings design fees as low as $6,000 to $9,000 because the structural shell and foundation already exist. A JADU within your home’s footprint costs even less.
• Match the unit to your lot before you fall in love with a design. A Boxabl or Tuff Shed-based unit on a flat lot is straightforward. That same unit on a canyon-edge lot in Del Cerro might need $6,000 of foundation engineering before the city will even look at it. Knowing your lot’s constraints first prevents paying for redesign.
• Ask about prefab-inclusive packages. Abodu, Cover, and Plant Prefab include stamped drawings with the unit purchase. If a prefab path fits your property, your out-of-pocket design cost drops by 50 to 70 percent. We quote these options side by side with conventional builds so you can see the difference in writing.
• Keep the unit under 750 sq ft. School impact fees, a meaningful line item in San Diego County, are typically waived for ADUs under 750 square feet. In the City of San Diego, that waiver can save you up to $4,000.
• Get your consultant reports once. Soils, survey, and arborist reports are property-specific, not design-specific. If your architect orders them and then you switch builders, you own those reports. Working with a design-build company means reports are ordered once, shared across the project, and never duplicated.

Buyer caution: any contractor who gives you a verbal ballpark and then asks for a deposit before ordering plans is not following The Kingswell Way. We say the price before the work, every time, in writing. No exceptions. If you want an exact number for your lot, call (619) 376-2760 and we’ll walk the property with you. Estimates are free.

San Diego ADU Permitting: What You’re Actually Paying For

When a San Diego homeowner asks what design and permitting costs, what they’re really asking is: what am I paying for that I can’t see? Fair question. You’re buying three things.

First, you’re paying for a plan set the City of San Diego (or Chula Vista, or El Cajon, or the County for unincorporated areas) will actually approve. The city reviews ADU plans for compliance with the 2025 California Residential Code (effective January 1, 2025), the California Green Building Standards Code, and the 2023 California Energy Code. A plan set that doesn’t address egress, fire separation, and setback requirements gets kicked back. Good design work anticipates review comments before they happen.

Second, you’re paying for the liability transfer. When a structural engineer stamps your foundation and framing drawings, they’re accepting professional responsibility for the design. That stamp is not optional for detached ADUs. It costs money because it carries weight.

Third, you’re paying the city. San Diego’s Development Services Department charges plan check and building permit fees based on project valuation. For a typical 600 to 800 sq ft detached ADU built for $180,000 to $250,000, the permit fees alone run $5,000 to $8,000 in the City of San Diego. Unincorporated county areas have similar fee schedules with slight variations. These are not negotiable, not markupable, and apply whether you work with us or anyone else.

How Long Does Design & Permitting Take in San Diego?

Design work takes 4 to 10 weeks from kickoff to a submittal-ready plan set, depending on how quickly you give feedback and whether consultants need to schedule site visits. Permitting adds another 60 to 120 days in most San Diego County jurisdictions. The City of San Diego currently reviews ADU permits under a state-mandated 60-day response window, but that window resets when corrections are requested. A project with no design errors can go from first submittal to issued permit in as little as 8 weeks. A project submitted with incomplete drawings can stretch 6 to 9 months.

That’s the hidden cost of cheap design: time. Every month your permit is held up is a month your rental income, in-law suite, or home office does not exist. A $10,000 design fee spread over a 9-month permitting ordeal costs you more in lost time than a $15,000 design fee that clears permit in 60 days.

Real San Diego ADU Cost Scenarios (2026)

Numbers on a table are useful. Numbers attached to a real lot are more useful. Here are three scenarios we see regularly.

Clairemont garage conversion to JADU, 480 sq ft. Existing garage in good structural shape, flat lot, single-story home. Design and permitting bundle came to $14,200. That included site assessment, architectural drawings, Title 24 calcs, city plan check, and permit fees. The build itself ran $95,000 because the shell was already standing. Total project: just under $110,000 for a rentable unit drawing $1,800 to $2,100 monthly in Clairemont.

Detached two-bedroom ADU in El Cajon, 750 sq ft. Flat lot, but set far back from the main panel with a long trenching run. Design and permitting ran $21,500, including $3,100 in upgrade engineering for the electrical run and a $1,800 permit expediter because the homeowner wanted to break ground before the holidays. The build ran $190,000. Monthly rental value in El Cajon for a two-bedroom detached unit: $2,200 to $2,600.

Hillside two-story ADU in Mission Hills, 900 sq ft. Slope lot, strict design review, view corridor considerations. Design and permitting came to $34,800. The soils report alone was $3,700, structural engineering hit $6,900 because of the retaining wall integration, and the design review overlay added $2,400 in consultant fees. The city’s plan check review was actually quick because the drawings addressed the slope issues up front, but the front-end engineering was the cost driver. Build cost: $280,000. That same unit on a flat lot would have saved $12,000 to $15,000 in design and permitting.

These scenarios are why we never quote a design package over the phone without seeing the property. The range is real, and it’s wide. But every number above is one we’ve actually seen in San Diego in the last 24 months.

FAQs – ADU Design & Permitting Cost

How much does it cost to design an ADU in San Diego?

Architectural design for a detached ADU in San Diego runs $8,000 to $15,000 for a complete plan set, or $2,500 to $5,000 if you’re using a prefab system like Abodu or Cover that includes stamped drawings. Garage conversions and JADUs trend lower, typically $5,000 to $9,000. Call (619) 376-2760 for a written quote on your specific property.

How much are ADU permit fees in San Diego?

City of San Diego permit fees for a detached ADU under 800 sq ft run $4,000 to $9,000, including plan check, building permit, and related surcharges. School impact fees are typically waived for units under 750 sq ft. Unincorporated county and other San Diego County cities run slightly lower or higher depending on jurisdiction. Your design-build firm should itemize every permit fee on your written estimate.

Is it cheaper to use a prefab ADU company for design and permitting?

Usually yes. Prefab manufacturers like Abodu, Cover, Plant Prefab, and Boxabl include stamped engineering in the unit purchase, which cuts your standalone design cost by 50 to 70 percent. You’ll still pay $3,000 to $8,000 for site adaptation, permit coordination, and city fees. Total design and permitting for a prefab ADU in San Diego typically lands between $8,000 and $15,000.

Can I skip the architect and design the ADU myself?

You can, but the City of San Diego will still require a California-licensed architect or engineer to stamp structural drawings for a detached unit. Homeowner-drawn plans almost always require corrections that add months and thousands in resubmittal fees. The savings rarely survive first contact with the plan check counter. A better savings path is choosing a prefab system with included drawings.

How long does ADU permitting take in San Diego, and does faster cost more?

Standard ADU permitting in San Diego takes 60 to 120 days from submittal to issuance. Faster paths exist: permit expediting services cost $1,200 to $3,000 and can cut 4 to 8 weeks off the review timeline. The real speed lever is design quality. Clean drawings from a firm that knows San Diego’s specific review comments get approved in one or two cycles; incomplete drawings can stretch 6 to 9 months.

What does The Kingswell Guarantee cover on design and permitting?

The Kingswell Guarantee puts a written price in your hands before any design work begins, shows up in the window we give you, leaves your property cleaner than we found it, and delivers a written guarantee on the work. If anything isn’t done right within the 365-day guarantee period, we come back and make it right at no charge. That’s the 365-Day Done Right Promise, and it’s in writing on every project, including design and permitting.

Why San Diego Homeowners Choose Lodgewick ADU Builders

A lodge is a small house on a larger property. That’s what an ADU is: a smaller home, on your lot, tuned to how you actually live. We’re the ADU company of the Kingswell family, established in 2010, and we’ve focused on nothing but accessory dwelling units, garage conversions, and home additions since the first day.

What that focus means in practice: we know which San Diego neighborhoods trigger coastal review, which ones sit in fire zones, and which ones have HOA documentation requirements that city staff won’t mention. We work directly with Abodu, Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie, so we can match the right construction system to your lot, your timeline, and your budget without being loyal to any one manufacturer’s margin.

Every Lodgewick San Diego project runs under The Kingswell Way:

• Written price first. Before any design work starts, you get a written price. Not a range, not an estimate subject to change, not a handshake. A number on paper you can hold us to.
• Real arrival window. Our crews show up in the window we gave you. If something changes, you hear from a person, not a text bot.
• Clean job site. We leave the property cleaner than we found it. Every day. This is a written commitment, not a slogan.
• Written guarantee. The 365-Day Done Right Promise is delivered in writing on every project before work begins. If the work fails within the guarantee period, we come back and fix it free.
• A live person answers. Call us at (619) 376-2760 at any hour, any day. Russ Delmar or a member of the Lodgewick San Diego team answers the phone. No voicemail loops, no call centers.

Russ Delmar leads our San Diego team. He’s the person you’ll talk to when you call, and the person who stands behind the written guarantee on your project. When a design question comes up mid-build, you’re not calling a national hotline. You’re calling the person whose name is on your paperwork.

Get Your Written ADU Design & Permitting Price

If you’re reading this, you’re likely trying to figure out whether an ADU pencils out on your property. The only way to know for sure is to get a real number for your actual lot. Our process starts with a site visit, not a phone script. We walk the property, check the setbacks, look at the utility runs, and review any HOA or historical district constraints. Then we hand you a written price for design and permitting.

That price covers the full plan set, structural engineering, Title 24 calculations, consultant reports your lot requires, city submittal, and permit fees. No surprises at the plan check counter. No add-ons when the reviewer asks for a soils report. Everything in writing, the way it should be.

Call (619) 376-2760 today for a free estimate on ADU design and permitting in San Diego. We serve the entire county, from Oceanside and Carlsbad down through Chula Vista and East County. A live person answers, 24 hours a day, 7 days a week.

Back to Lodgewick ADU San Diego home

Written by Russ Delmar, Owner at Lodgewick ADU San Diego, serving San Diego County since 2010.

Pricing reflects the San Diego market as of 2026. Lodgewick ADU San Diego offers free estimates – call (619) 376-2760.