How Your ADU Project Goes

Mazzamuto Construction · ADUs

How your ADU project goes

You’ve met your designer. Here is every step from here to a finished, permitted unit: what happens, who does it, and what you get. Read it before you sign anything, so nothing later is a surprise.

If you read one thing

The seven things to know before you sign

  1. The design fee is paid in two halves. Half when design begins. Half when your design is finished.
  2. Design starts about two weeks after your first payment. That is our designer’s current backlog, give or take.
  3. The design contract covers the architectural plans. Engineering, Title 24, a soils report or a survey are added as change orders, only if your project needs them.
  4. You review the plans three times and approve them before anything is priced or submitted.
  5. We present your pricing in person. At least 60 minutes at our showroom. We don’t release a proposal before that.
  6. A $1,000 deposit after you approve the proposal puts you in line for project prep.
  7. No start date until the permit is approved and deliveries are confirmed. The date we give you is one we can keep.
Payment Your decision Possible added cost Good to know

Phase 1

Design: the unit is drawn, engineered and permit-ready before anyone prices it

An ADU starts with your lot, not a floor plan. What the ground is, where the property lines and utilities run, and what your city allows decide what can be built. Your designer works that out first.

  1. 1

    We research your lot

    Your designer checks your property with the building department before promising anything: zoning, setbacks, easements, height, utilities and sewer. The design is built on what your city will approve.

    You getA straight answer on what is possible on your lot.

  2. 2

    Your design contract

    You receive a written design contract through Buildertrend, our client portal. It states the process, the deliverables, the responsibilities and the fee.

    Your decisionRead the contract and accept it in Buildertrend. Nothing starts until you do.

    You getEverything you are paying for, in writing, before design begins.

  3. 3

    Your first payment, then design begins

    PaymentHalf of the design fee is due when design begins. The other half is due when your design is finished.

    Good to knowDesign starts about two weeks after your first payment is received, give or take. That is our designer’s current backlog.

    Once the first half is received, your designer reaches out to get started.

    You getA start you can plan around.

  4. 4

    Site mapping

    We map the site: property lines, setbacks, easements, existing buildings, trees, slope, and where the utilities and the sewer run. This is what tells us exactly where your unit can sit.

    You getA site plan showing your unit on your lot.

    Possible added costIf your lot needs a survey, it is added as a change order.

  5. 5

    Soil testing, if your lot needs it

    Some lots need a soils report: a slope, clay, or soil the building official has questions about. When yours does, your designer coordinates it. The engineer then chooses the foundation for the ground you actually have.

    You getA foundation designed for your ground, not a guess.

    Possible added costA soils report is added as a change order, only if your lot needs one.

  6. 6

    First plan review

    Your designer prepares preliminary layouts and walks you through them, usually on a video call so you can see the drawings on screen. You tell her what works and what doesn’t.

    You getYour first look at the unit on paper, and a say in it.

  7. 7

    Revisions and second review

    She revises the plans with your changes and reviews them with you again. This repeats until the layout is right.

    Good to knowThis is the time to change your mind. Changes are easy and inexpensive now. After engineering, a layout change means the engineering is redone.

    You getA layout you have approved, before anything is engineered.

  8. 8

    Your materials, curated by your designer

    Your designer curates every material and finish for your project: cabinets, surfaces, flooring, plumbing, lighting, hardware, paint and exterior finishes. You meet in our showroom in Martinez and choose with real samples in your hands. She then hands the full list to our estimating team, so every item is priced from what you actually chose, not from an allowance.

    You getA mood board, real samples, and one documented list of everything that goes into your unit.

  9. 9

    Engineering and energy compliance

    We coordinate the structural engineer and fold the engineering into the plans. Energy compliance (Title 24) and green building requirements are prepared as part of the set.

    You getA full set of structural drawings.

    Possible added costEngineering and Title 24 are outside the architectural plans. They are added as change orders, based on what your project requires.

  10. 10

    Final plan review and your approval

    Before anything is submitted or priced, your designer goes through the complete set with you, page by page: layout, elevations, structure, electrical, plumbing and every selection.

    Your decisionYou approve the plans. Only then do they move to estimating.

    You getThe last word on your plans.

  11. 11

    Permit-ready plans

    PaymentYour design is finished. The second half of the design fee is due now.

    Every decision is now in one construction set. Your designer, estimator, plan reviewer, project manager and crew all build from the same drawings.

    The plans we develop are guaranteed to get you a permit. And they are yours. They are not tied to us.

    You getPermit-ready plans that belong to you.

The part most contractors skip

Your designer stays with you, from the first drawing to the last day of the build

She doesn’t hand off a set of plans and disappear. She reviews the plans with you at every stage, curates your materials, answers the city’s questions during plan check, and stays on your project through construction. When a question comes up on site about what was drawn or what was chosen, the person who drew it and chose it with you is the one who answers.

Phase 2

Your takeoff: real pricing from finished plans

We price the plans, not a general idea. That is why design comes first.

  1. 12

    Your takeoff is built

    Our estimating team measures every quantity from your finished plans and prices it from the materials your designer curated, with labor data from our own jobs and current vendor pricing. You hear from Christian, our lead estimator, when it starts and when it is done.

    You getLine-itemed pricing down to the smallest detail.

  2. 13

    We present your pricing in person

    Good to knowWe don’t release a proposal until we’ve gone through it with you in person. Plan on at least 60 minutes at our showroom.

    Because of how detailed your takeoff is, we want the time to go through it thoroughly. You pick the time from a booking link, and your designer is there too.

    You getEvery line explained before you decide anything.

  3. 14

    You approve the proposal

    Your proposal is released in Buildertrend after the presentation. If something needs a second look, we revise it and tell you when the new version is there.

    Your decisionWhen everything looks right, you approve the proposal in Buildertrend.

    You getA proposal tied to the plans you approved.

Phase 3

Preparing your job: permits, materials and a start date we can keep

We don’t give you a start date until the permit is in hand and the delivery dates are confirmed. A date we can’t keep helps no one.

  1. 15

    Your $1,000 deposit

    PaymentA $1,000 deposit puts you in line for project prep. Our finance team sends the invoice through Buildertrend.

    You getYour place in line.

  2. 16

    Meet your project manager

    Our project leadership team meets to go over every detail of your job. Then Mike, your project manager, introduces himself and calls you.

    You getOne person to call.

  3. 17

    Sewer district, then the permit

    An ADU is reviewed by more than one agency. The sewer district reviews the plans, and in Martinez it stamps them before the building permit application goes in. Then the city or county reviews the application. This is plan check: the reviewer sends comments, your designer and the engineer answer them, and the plans are resubmitted until they are approved. We submit, track every comment and handle the corrections.

    You getUpdates from your project manager at each turn.

  4. 18

    Ordering and your start date

    Good to knowWe don’t give a start date until the permit is approved and the delivery dates are confirmed.

    Once the permit is approved we order materials and track every delivery date. When those are firm, your project manager coordinates a start date with you.

    You getA start date built on confirmed deliveries.

Phase 4

Building: one superintendent on site, everything in one place

  1. 19

    Construction

    Travis, your job superintendent, runs your job day to day and knows it inside and out. Your designer stays on your project through the build, so design questions on site are answered by the person who drew the plans. Daily updates, photos, the schedule, selections and messages all live in Buildertrend.

    You getA daily record of your project.

  2. 20

    Final stretch and walkthrough

    Travis walks the unit with you and lists anything that needs a touch-up. The crew works through the list, then comes the final inspection and closing paperwork.

    You getA finished, permitted unit.

Money, in order

When you pay, and for what

Step 3Design fee, first halfDue when design begins.
During designChange orders, if neededEngineering, Title 24, soils, survey. Only what your project requires. You approve each one first.
Step 11Design fee, second halfDue when your design is finished.
Step 15$1,000 depositPuts you in line for project prep.

Construction payments follow the schedule in your construction agreement, which you review with your proposal.

How it’s billed

What’s in the design contract, and what’s added only if your project needs it

Your design contract covers the architectural plans. Every lot is different, so the reports and engineering a city asks for are different too. Rather than charge everyone for everything, we add those as change orders, based on what your project actually requires. You see each one in Buildertrend and approve it before the work is done.

In your design contract

  • Research with the building department
  • Site plan: property lines, setbacks, easements, utilities
  • Plan reviews with you at every stage
  • Layouts, revisions, renderings and a mood board
  • Floor plans, elevations and sections
  • Every material curated by your designer and documented
  • Coordination of the engineer and every consultant
  • Coordination with the sewer district
  • Permit-ready plans, guaranteed to get you a permit
  • Plans that belong to you

Added by change order, only when necessary

  • Structural engineering and structural drawings
  • Title 24 energy calculations
  • Soils (geotechnical) report
  • Survey
  • Any other report or engineering the city or your lot requires

Your designer tells you which of these your project needs, and why, as soon as she knows.

One designer works with you from the first visit to the end of the job, through the build itself.

Plain language

The rules that shape an ADU in California

These are state rules as of 2026. Your city and your lot can add to them, and your designer confirms what applies to yours.

ADU or JADU
An ADU is its own home: detached, attached, or converted from existing space. A junior ADU is up to 500 square feet inside your house. An attached garage counts as inside the house. A detached garage becomes an ADU.
Setbacks
Four feet from the side and rear property lines. No setback when an existing structure is converted.
Height
At least 16 feet is allowed for a detached unit. Martinez allows 18, plus 2 to match a roof pitch.
Approval
No public hearing. The agency has 15 business days to say the application is complete, then 60 days to decide.
Fees
No impact fees on a unit of 750 square feet or less. School fees can apply from 500 square feet. The sewer district charges a fee on a new unit and none on a conversion.
Parking
No replacement parking is required when a garage is converted.
Fire sprinklers
Only if your main house is required to have them.
Solar
Solar may be required on a newly built detached unit. Not on an attached unit or a conversion.
Sewer
An attached unit uses the house’s sewer line. A detached unit connects to it outside. The sewer permit is separate from the building permit.
Power
The utility meters each home. A junior ADU does not need its own meter.

Said plainly

What can change the cost or the timeline

Most surprises on an ADU come from the lot, not the building. We look for them in design, while they are still easy to plan for.

  • The ground. Clay or a slope can change the foundation.
  • The sewer. The district, the line, and sometimes rights across a neighbor’s lot.
  • More than one agency. City or county, sewer district, fire, school district and the utility each have a say.
  • Access. Some jurisdictions require a path from the street to the unit.
  • Exceptions. When a lot needs a variance, that is its own application.
  • Changes after engineering. A layout change after the engineer is finished means the engineering is revised.

One voice at a time

Who you’ll hear from

JackieYour designer. With you through the plans, the materials and the whole build.
ChristianLead estimator. Your takeoff and proposal.
HersheyFinance. Invoices and your deposit.
MikeProject manager. Permits, ordering and your start date.
TravisJob superintendent. Your day-to-day contact during construction.

Keep reading

What to look at next