📞 (831) 319-6492  |  📧 richrod@peninsula.construction  |  @peninsulaconstructionca  |  CSLB #723364
6–12 MoTypical Timeline
$150K+Starting Cost
100%Permit Handled
FreeConsultation
What To Expect

Building an ADU Is a Journey — Here's Your Map

An ADU is one of the most valuable investments you can make on the Central Coast. It adds rental income, housing for family, and significant property value. It's also one of the most complex projects a homeowner can take on. We've walked hundreds of clients through this process. This guide tells you exactly what happens at every stage — what we do, what you'll decide, what to watch out for, and how to save time and money along the way.

01
Weeks 1–2

Site Assessment & Feasibility

Before a single drawing is made, we visit your property and determine exactly what's possible — and what isn't.

What We Do

We measure your lot, review your parcel map, check setback requirements, confirm utility capacity (water, sewer, electrical), assess soil conditions, and evaluate access. We look at how your city's ADU ordinance applies to your specific property. Some lots allow 1,200 sq ft units. Others are limited to 500 sq ft by zoning overlays.

💡 Money-Saving Tip Before signing anything, ask your contractor to pull your parcel report and confirm your sewer lateral size. An undersized lateral can add $10,000–$25,000 to your budget and is a surprise no one wants after permits are submitted.

Questions to Ask Your Contractor

  • What is the maximum square footage allowed on my lot?
  • Are there any deed restrictions or HOA rules I should know about?
  • Does my sewer lateral have capacity for an additional unit?
  • Will I need a new electrical panel or meter?
  • Can you build detached, attached, or is a garage conversion better for my lot?
  • Are there fire setback requirements near my property lines?
⚠️ Common Mistake Skipping the feasibility phase and going straight to design. If you commission full architectural drawings before confirming what your lot allows, you may pay $5,000–$15,000 for plans that can't be built.
02
Weeks 2–6

Design & Architectural Plans

Good design decisions here save weeks of delays and thousands of dollars in construction. This is where your ADU takes shape.

What We Do

Our design team creates fully engineered architectural plans tailored to your lot and your city's requirements. We offer pre-approved floor plan templates under 750 sq ft that can dramatically speed up permit approvals — in some cities from 4 months down to 4–6 weeks. For larger or custom ADUs, we work through a full design process including structural engineering, Title 24 energy calculations, and stormwater compliance.

💡 Time-Saving Tip If your ADU is under 750 sq ft and your city participates in California's pre-approved ADU plan program, you can cut permit review time significantly. Ask us if your city qualifies — many on the Central Coast do.

Questions to Ask Your Contractor

  • Do you have pre-approved plans that fit my city's program?
  • Who handles engineering — in-house or a third party?
  • How many design revisions are included before extra charges apply?
  • Can I see 3D renderings before plans are finalized?
  • What finishes and fixtures are included in the base price?
  • How do I future-proof the unit for aging-in-place or rental use?
⚠️ Common Mistake Choosing finishes based on your own taste instead of rental market standards. If this is a rental unit, durable LVP flooring and neutral quartz counters will outperform hardwood and tile every time — lower maintenance cost, higher rental appeal.
03
Weeks 4–20 (varies by city)

Permitting & City Approvals

This is the stage that most ADU projects stall at. We've navigated every city on the Central Coast — here's what to expect.

What We Do

We handle the complete permit application — architectural plans, structural engineering package, Title 24 energy compliance report, stormwater management plan, and all city-specific submittal forms. We respond to plan check corrections, attend planning department meetings when needed, and track your permit through the review process. You don't call the city — we do.

💡 Money-Saving Tip California law (AB 2221 and SB 897) limits the fees cities can charge for ADU permits and prohibits most discretionary review. If your city is trying to charge excessive impact fees or require a hearing, it may be violating state law. Ask us — we've pushed back successfully on illegal fee demands.

Questions to Ask Your Contractor

  • How long does permit approval typically take in my city?
  • Do you handle plan check corrections in-house?
  • What are the total permit fees for my project?
  • Will there be school district fees or utility connection fees?
  • Can we start any site work before permits are issued?
  • What happens if the city comes back with major corrections?
⚠️ Common Mistake Starting any grading, demolition, or foundation work before permits are approved. This can result in stop-work orders, fines, and having to undo completed work. No reputable contractor starts before permits are in hand.
04
Weeks 2–5 after permit

Site Prep, Foundation & Framing

Permits are in hand. Now things move fast. This is the most visible phase of construction — your ADU goes from a flat lot to a framed structure.

What We Do

We mobilize equipment, prep the site, and pour the foundation — type depends on your soil report (slab-on-grade is most common for ADUs, though some sites require a raised foundation). Once the foundation cures (typically 7–10 days), framing begins. A typical ADU is framed in 2–3 weeks. We schedule the framing inspection before any sheathing goes on so the city can verify all structural members.

💡 Headache-Saving Tip Walk the site with your contractor the day grading begins. Confirm the ADU location, confirm where the utility trenches will run, and confirm access during construction. Changes after grading starts cost money and time.

Questions to Ask Your Contractor

  • What foundation type are you planning and why?
  • When will I see the framing inspection scheduled?
  • How will you protect my main home's landscaping and driveway?
  • Will there be a dumpster and where will it be located?
  • Who is the site supervisor I can call with questions?
  • How often will I receive progress updates?
⚠️ Common Mistake Not having a dedicated site contact. On a well-run ADU project you should have one person's cell number who is on-site or reachable daily. If your contractor can't tell you who that person is, that's a red flag.
05
Weeks 4–8 after framing

Mechanical, Electrical & Plumbing (Rough-In)

The walls are open. This is your last chance to change anything without tearing drywall. The rough-in phase is where your ADU's systems are built — and where hidden costs love to appear.

What We Do

Licensed subcontractors install all rough plumbing (water supply, drain lines, vent stacks), electrical (panel, circuits, outlets, lighting rough-in), and HVAC ductwork or mini-split line sets. Each trade is inspected by the city before walls are closed. We coordinate all three trades to avoid conflicts in the walls and ceilings, which is where inexperienced contractors create expensive problems.

💡 Money-Saving Tip If you're planning to add EV charging, a hot tub, or a washer/dryer in a specific location — now is the time to rough in the circuits. Running conduit during rough-in costs a few hundred dollars. Running it after drywall can cost $2,000–$5,000.

Questions to Ask Your Contractor

  • Are your electrician and plumber licensed and insured separately?
  • Who pulls the sub-permits for each trade?
  • Can I walk the rough-in with you before the inspection?
  • Where will the electrical panel be located?
  • Is the HVAC system included or a separate bid?
  • Are you pre-wiring for internet/cable or is that my responsibility?
⚠️ Common Mistake Assuming EV charging, washer/dryer hookups, and smart home wiring are included. Always get a written list of exactly what is and isn't in the electrical scope. Verbal promises disappear fast once walls are closed.
06
Weeks 6–12 after rough-in

Finishes, Inspections & Move-In

The finish phase is where your ADU transforms from a construction site into a home. It's also where attention to detail matters most — and where many contractors rush.

What We Do

We install insulation, hang and finish drywall, apply paint, install flooring, set cabinets and countertops, install all plumbing fixtures and trim, hang light fixtures, install doors and hardware, and complete all exterior work including paint, trim, and landscaping restoration. Final inspections are scheduled and we walk every punch-list item with you personally before we consider the project complete. We also walk you through your new unit — showing you shut-off valves, breaker panel, HVAC operation, appliances, and any maintenance items to know about.

💡 Long-Term Tip Photograph every wall before drywall goes up. Having a photo record of where every pipe, wire, and duct runs will save you significant money if you ever need repairs or renovations down the road. We do this for every project.

Questions to Ask Your Contractor

  • Who does the final walk-through with me?
  • What is your punch-list process — how do items get resolved?
  • Will you show me where the water shut-off, gas shut-off, and breaker panel are?
  • What warranty do you provide on labor and materials?
  • How do I request warranty work after move-in?
  • Can you provide as-built drawings for my records?
💡 Maintenance Tips for Your New ADU Change HVAC filters every 3 months. Test smoke and CO detectors monthly. Know where your main water shut-off is before you need it. Caulk around tubs and showers annually to prevent water intrusion. Flush your water heater once a year to extend its life.

You've Done Your Homework. Let's Build.

Ready to take the next step? Get a free estimate and talk directly with the owner — no sales team, no runaround.

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ADU FAQ

Straight answers to the questions we hear most.

Can I rent my ADU immediately after the final inspection?

Yes — once you have your certificate of occupancy you can rent immediately. There is no additional waiting period on the Central Coast.

Do I need to live on the property to build an ADU?

California eliminated owner-occupancy requirements in 2020. You can build and rent an ADU even if you don't live on site.

Can you take over if I already started or have partial permits?

Absolutely. We step in at any stage — whether you have approved plans, a foundation poured, or a project stalled mid-build. We assess what's been done, identify any issues, and give you a clear path to completion.

What's the difference between a JADU and a standard ADU?

A JADU (Junior ADU) is under 500 sq ft and created within the existing footprint of your home — typically a converted bedroom or garage area. It requires less permitting but has more restrictions. A standard ADU can be detached and larger.

How much rental income can I expect?

On the Central Coast, a well-finished 1BR ADU typically rents for $1,800–$2,800/month depending on location and finishes. A 2BR can command $2,500–$3,500. We're happy to share current rental comps for your neighborhood.

Will an ADU increase my property taxes?

Yes, but only on the value of the new construction — not your existing home. Your base assessment is not reassessed. Typical increase is $150–$400/year depending on the ADU's finished value.

What if my neighbor objects to the ADU?

For most ADUs, neighbor objections cannot legally block construction — California state law preempts local opposition for projects that comply with state ADU law. We've helped clients navigate this many times.

How do I finance an ADU build?

Common options include cash-out refinance, HELOC, construction loan, and the state's CalHFA ADU grant program (up to $40,000 for eligible homeowners). Visit our Financing page for details.

Ready to Start Your ADU?

Call Richie directly for honest advice — no sales pressure, just straight answers about your specific property.

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