In San Diego, building an ADU (Accessory Dwelling Unit) is more than just slapping up a second unit behind your house—and the permitting process is often the most complex hurdle. Getting permits right is critical not just for legality and code compliance, but for saving time, avoiding costly redesigns, and protecting your investment. In this article, I (as a permitting specialist / project manager at Sheiner Construction, CSLB License # [insert your number]) walk you through exactly “ADU San Diego permit timeline”, the realistic steps and costs involved, and what homeowners commonly overlook—and how you can avoid those mistakes.
Permit Checklist in San Diego: What You Need (Drawings, Sewer, Parking Exceptions, etc.)
Getting an ADU permit in San Diego starts long before you step into the city’s Development Services Department. A well-prepared permit packet saves weeks of back-and-forth corrections and unexpected costs. Think of it as your ADU’s roadmap—every missing item adds delays. You’ll need architectural drawings, utility clearances, and supporting documents that align with San Diego’s zoning, building, and coastal requirements. The best part? Once you’ve submitted a complete and coordinated set, your project can glide through plan review in a fraction of the normal time. Here’s the official Sheiner Construction permit checklist—simple enough to follow, yet detailed enough for approval.
Site Survey & Property Lines
Before anything else, you need a current property survey. San Diego requires accurate boundary and topographic information to confirm setbacks, easements, and access routes. Many homeowners skip this, only to discover that an existing fence isn’t actually on the property line. Hire a licensed surveyor to produce an ALTA or boundary survey—especially if you’re in hillside or coastal overlay zones. This data drives every dimension on your drawings, helping avoid expensive redesigns after city review.
Architectural & Structural Drawings
Architectural plans show what your ADU will look like; structural plans show how it’ll stand safely. The city reviews everything—from framing and foundation details to window egress and fire separation walls. If your ADU shares walls or utilities with the main house, those connections must be clearly documented. Having these plans sealed by licensed professionals speeds up plan review. Sheiner Construction’s permitting team often bundles architecture and engineering together to cut coordination delays.
Grading, Drainage & Soils Reports
Even for small backyard units, San Diego often asks for basic grading or drainage documentation to show proper water runoff control. If your lot slopes or sits in a stormwater-sensitive area, a civil engineer may need to prepare a grading plan and soils report. These reports prove your site can handle the load and won’t cause erosion or flooding problems. Ignoring this step is one of the biggest culprits behind multi-week permit resubmittals.
Sewer / Utility Capacity Approval
Before your ADU connects to existing utilities, the city checks whether your current systems can handle the extra load. Sewer lateral upgrades are common and can cost several thousand dollars. You’ll need a “will-serve” letter from the water and sewer departments and possibly an electrical load calculation if your panel is undersized. At Sheiner Construction, we often coordinate these approvals early to prevent your project from being flagged mid-review.
Parking Exceptions & Waiver Documentation
One of the perks of San Diego’s ADU program is that many projects qualify for parking exemptions—especially if you’re within a half-mile of public transit or converting an existing garage. However, you’ll need proof: a printed map showing transit proximity or a clear notation on your plans. Forgetting this is a classic rookie mistake. Our permitting team ensures your waiver request is backed by city-acceptable documentation, saving unnecessary corrections.
Energy & Code Compliance Exhibits
California’s Title 24 energy standards apply to all ADUs. You’ll need an energy consultant to prepare compliance documentation—covering insulation, windows, HVAC efficiency, and lighting. You’ll also need smoke, carbon monoxide, and fire separation details that align with local fire codes. Submitting incomplete energy forms is one of the top reasons for permit delays. At Sheiner Construction, we integrate these reports early to keep your ADU San Diego permit timeline on track.
Special Reviews (Coastal, Historic, etc.)
If your property falls within the coastal zone or a historic district, expect additional layers of review. Coastal Development Permits (CDPs) or Historical Resource Board clearances can add weeks. It’s not just red tape—these agencies ensure the ADU aligns with neighborhood character and environmental protections. Our team flags these zones early and submits concurrently to cut processing time in half.
Realistic Timeline: Design → Permit → Build
When planning your ADU in San Diego, the biggest surprise for most homeowners isn’t the cost — it’s the time. The ADU San Diego permit timeline depends heavily on how prepared your plans are, how fast the city reviews your submittal, and whether your contractor coordinates efficiently. On average, Sheiner Construction projects move from design to permit in about 8–14 weeks, then another 3–6 months to build. The good news? You can shave off weeks if you plan smartly and avoid re-submittals. Let’s break down what happens in each phase and where time is often lost or saved.
Pre-Design & Due Diligence
Every efficient project starts with a solid discovery phase. This includes reviewing your property zoning, overlay zones, utility access, and site limitations before design even begins. San Diego’s zoning maps and Development Services portal let you check setbacks, coastal requirements, and parking exemptions. A quick zoning review helps you decide whether to build a detached ADU, convert a garage, or add a second story. Sheiner Construction usually completes this step in 1–2 weeks, preparing a feasibility report so there are no surprises later. Homeowners who skip this step often find themselves redesigning halfway through — losing months.
Design & Preparation
The design phase is where your ADU vision comes to life. Expect 3–5 weeks for design development, depending on complexity. During this time, architects create floor plans, elevations, and 3D concepts while engineers draft structural details. Title 24 energy reports and utility checks happen in parallel. The goal? Submit a “permit-ready set” that meets all city requirements on the first try. Sheiner Construction’s in-house coordination means architects, engineers, and energy consultants collaborate in real time — trimming the ADU San Diego permit timeline by up to 30%.
Plan Review & Permit Approval
Once your permit set is submitted, the City of San Diego’s Development Services Department reviews it. A typical review cycle lasts 4–8 weeks, with multiple departments (planning, fire, structural, electrical, and environmental) checking compliance. The first cycle usually returns with comments — think of it as a “to-do list” from the city. Responding quickly to these corrections is critical. We’ve seen homeowners lose months just waiting to resubmit. With a permitting specialist managing your file daily, that response time drops to a few days. When approvals come through, you’ll receive an official building permit — the green light to start construction.
Construction & Inspections
Building your ADU takes 3–6 months, depending on type and size. Garage conversions often finish in 3 months, while detached units with new foundations take longer. Each stage — foundation, framing, plumbing, electrical, and finishes — requires inspections. Scheduling them promptly keeps the project moving. Having a contractor familiar with San Diego’s inspection rhythm makes all the difference. Sheiner Construction’s project managers coordinate directly with inspectors, preventing unnecessary stop-work delays.
Infographic — Sample Gantt Timeline (Simplified)
PhaseTasks -DurationResponsible Party
Pre-Design-Site check, zoning, feasibility1–2 weeksHomeowner + Sheiner
Design-Drawings, energy, utilities3–5 weeksArchitect + Engineer
Permit Review-City plan check, corrections4–8 weeksCity + Sheiner
Construction-Build + inspections12–24 weeksContractor
Total- Start to finish20–36 weeks—
Client Story – “Time Saved with a Smart Submittal”
When the Gonzalez family in Clairemont decided to convert their garage into a 450 sq ft ADU, they expected a 10-month process. By using Sheiner Construction’s coordinated design-permit package, their plans were approved in just 7 weeks — cutting nearly two months off the normal review period. “We couldn’t believe how smooth it went,” Mrs. Gonzalez said. “They knew exactly what each city reviewer needed before we even submitted.” That’s the power of a complete submittal — fewer surprises, faster permits, and less stress.
Cost Bands with Examples in San Diego
Let’s talk numbers — the part everyone’s curious about. The cost of an ADU in San Diego varies widely depending on size, type, and site conditions, but understanding realistic price bands helps homeowners budget smartly and avoid sticker shock. As a permitting specialist at Sheiner Construction (CSLB License #XXXXXX), I’ve seen hundreds of ADU projects, from compact garage conversions to full two-bedroom detached units. On average, homeowners spend between $140,000 and $380,000, but what you actually pay depends on three main components: soft costs, hard construction costs, and permit fees.
Below, we’ll break down typical ranges for different ADU sizes — with real examples from San Diego neighborhoods — so you know exactly where your project might land.
Small / Conversion ADU (≤ 400 sq ft)
Garage conversions and small attached ADUs are the most cost-effective way to add livable space. These typically range between $140,000–$200,000. Most of that goes toward insulation, waterproofing, and bringing existing structures up to modern code. Because the structure already exists, soft costs (like architecture and permits) are lower — usually around $10,000–$18,000 total.
For instance, a client in North Park turned their old detached garage into a studio ADU with a kitchenette and bath for about $165,000, including permits. With careful planning and early utility checks, they avoided costly sewer line upgrades. Projects like this can often be designed, permitted, and built in under 6 months when done right.
Mid-Size ADU (400–750 sq ft)
This is the sweet spot for most homeowners — enough space for a full bedroom and living area without breaking the bank. Expect total costs between $200,000–$275,000. Soft costs typically fall around 8–10% of the total, while construction drives the rest.
For example, a 650 sq ft detached ADU in Clairemont with a full kitchen, HVAC, and new foundation cost roughly $240,000 from permit to completion. The key savings came from standardized floor plans and minimal grading work. Sheiner Construction’s design-build model shortens both the ADU San Diego permit timeline and construction window because all specialists coordinate in-house.
Large / Detached ADU (> 750 sq ft)
Detached ADUs — especially two-bedroom layouts — can range from $280,000 to over $380,000. The bigger the build, the more utility and site prep work you’ll need. These are effectively small houses, complete with independent foundations, meters, and sometimes fire sprinklers.
One recent La Mesa project — an 850 sq ft, two-bedroom ADU with custom finishes — cost $355,000 all in. The homeowners invested more upfront in solar and energy efficiency, which reduced long-term utility bills and boosted property value. Remember, construction materials and labor prices shift seasonally, so always request updated estimates before breaking ground.
Cost Breakdown: Fees vs Soft Costs vs Construction
Here’s how the budget usually shakes out for San Diego ADUs:
CategoryTypical Range (% of Total)What It Covers
Soft Costs-8–12%Design, engineering, energy reports, and permits
Permit Fees-2–4%City plan review, school fees, sewer/water connection
Hard Construction-80–90%Site work, framing, finishes, utilities, inspections
Pro Tip: Some homeowners assume permit fees are the main cost driver. In reality, the construction phase eats up the majority of your budget. Early coordination and accurate design sets can save tens of thousands by preventing change orders later.
💡 Infographic — Average ADU Cost by Type (San Diego 2025)
- Garage Conversion (≤ 400 sq ft): $140K–$200K
- Mid-Size ADU (400–750 sq ft): $200K–$275K
- Detached ADU (> 750 sq ft): $280K–$380K+
- Permit & Soft Costs Combined: ~10–15% of total
Common Mistakes Homeowners Make & How to Mitigate
Even the most enthusiastic homeowners can hit roadblocks during their ADU San Diego permit timeline. From missing paperwork to underestimating costs, small errors can snowball into months of delay. As a permitting specialist with Sheiner Construction (CSLB License #XXXXXX), I’ve seen firsthand how preventable mistakes waste time and money. Let’s break down the top pitfalls—and how to stay clear of them.
Incomplete or Uncoordinated Drawings
The #1 reason for rejected ADU permit applications? Incomplete or inconsistent drawings. If your architectural plans don’t align with structural or utility layouts, city reviewers will flag them immediately. Each correction cycle adds 2–4 weeks.
To prevent this, always ensure your design team uses the same updated base plans. At Sheiner Construction, architects, engineers, and energy consultants work from one shared model—reducing revisions to almost zero. The result: smoother approvals and faster permits.
Underestimating Utility Capacity or Sewer Cost
Many homeowners assume their existing utilities can handle an extra unit. Unfortunately, that’s not always true. If your sewer lateral is undersized or your electrical panel can’t support new loads, you’ll need costly upgrades mid-project.
To mitigate this, have a utility capacity check completed early in design. A quick site visit from a plumber or electrician can save you thousands later. Sheiner Construction performs these checks during feasibility to keep the ADU San Diego permit timeline on schedule.
Improper Parking or Setback Assumptions
San Diego’s ADU parking exemptions are generous—but only if you meet the criteria. Projects within a half-mile of public transit or converting existing structures may be exempt, but many homeowners assume they qualify without verifying. If the city finds your ADU requires parking, you’ll need to revise site plans.
Always confirm eligibility with the City of San Diego’s ADU Parking Waiver Map and note the justification directly on your site plan. At Sheiner, we prepare waiver documentation as part of every submittal to avoid confusion.
Not Accounting for Code Changes During Approval
City building codes evolve every few years, and ADU regulations in California are especially fluid. A project designed under 2022 codes may be reviewed under 2025 standards if delayed. That can mean redrawing plans or adding new energy measures.
To stay ahead, keep your consultant in the loop about any code updates from the City of San Diego Development Services Department. Linking directly to official ADU pages not only builds trust but also keeps your project compliant and current.
Delaying Permit Corrections
When the city sends comments, time is of the essence. Many homeowners lose months simply because they take too long to resubmit. Reviewers often handle applications in order received—so every delay pushes your file back in the queue.
Set a goal of turning corrections around within 3–5 business days. At Sheiner Construction, we maintain daily contact with reviewers to clarify issues quickly. Fast responses equal fast approvals—it’s that simple.
Choosing the Wrong Contractor or Permit Consultant
Not all contractors understand the intricacies of San Diego’s ADU permitting process. A general home remodeler might build well but struggle with zoning interpretations or energy documentation.
Choose a licensed contractor with proven ADU permit experience and familiarity with the city’s electronic plan review portal. Companies like Sheiner Construction ADU permit help specialize in both design and permitting, ensuring no step gets lost in translation. A knowledgeable ADU contractor San Diego keeps your project compliant, efficient, and stress-free.
Infographic — “Top 6 ADU Permit Mistakes to Avoid”
- ❌ Missing or uncoordinated drawings → ✅ Unified, updated plans
- ❌ Skipping early utility checks → ✅ Confirm capacity before submittal
- ❌ Wrong parking assumptions → ✅ Verify waiver eligibility
- ❌ Ignoring code changes → ✅ Track updates from city ADU portal
- ❌ Slow response to city comments → ✅ Resubmit within 3–5 days
- ❌ Hiring the wrong team → ✅ Work with an ADU-experienced contractor
Conclusion
Building an ADU in San Diego is one of the smartest ways to boost property value, generate rental income, or create multi-generational living space—but only if you navigate the ADU San Diego permit timeline the right way. The key takeaway? Preparation is everything. A well-organized permit packet, realistic timeline expectations, and an experienced contractor make all the difference between a smooth approval and a frustrating delay.
At Sheiner Construction (CSLB License #XXXXXX), our permitting specialists live and breathe ADU compliance. We handle everything—from architectural plans and utility approvals to city coordination—so homeowners don’t have to play guessing games with submittals and code updates. We’ve seen clients cut months off their schedules simply by getting the details right from day one.
Remember, local building rules and fees evolve. Always double-check current ADU standards on the City of San Diego’s official ADU page before applying. Doing so not only builds your project on a solid foundation but also ensures long-term compliance and peace of mind.
If you’re looking to get started, reach out for Sheiner Construction ADU permit help—your trusted ADU contractor San Diego. Together, we’ll make your backyard dream a reality, one approved permit at a time.
7. FAQ (Schema-Ready Section)
Q1: How long does it take to get an ADU permit in San Diego?
Most homeowners can expect a total permit processing time of 8–14 weeks, depending on project size and completeness of plans. Projects with complete, coordinated drawings often move much faster.
Q2: What are the typical costs to build an ADU in San Diego?
Costs generally range from $140,000 for garage conversions to $380,000+ for large detached units. Permit and design fees make up about 10–15% of total costs.
Q3: Can I build an ADU without adding parking?
Yes, if your property meets exemption rules. Homes within half a mile of public transit, or converting existing structures like garages, are typically exempt from adding parking spaces.
Q4: What documents are needed for an ADU permit?
You’ll need architectural and structural drawings, energy compliance reports, sewer and utility approvals, and possibly coastal or historic review documents depending on your property’s zone.
Q5: Who should I contact for professional help with ADU permits?
Reach out to Sheiner Construction ADU permit help — we handle full design, engineering, and city submittal coordination. Licensed and experienced ADU contractor San Diego specialists save you time, stress, and costly rework.