ADUs & additions in Modesto
Modesto ADU Contractor & Home Addition Builder
Evaluate detached ADUs, garage conversions, in-law suites, and room additions with one contractor coordinating the property review, permit path, construction, inspections, and closeout.
Complete project coordination
A connected plan from first review through closeout.
A useful ADU plan starts with the actual Modesto property—not a generic floor plan. The lot, existing structures, access, utilities, setbacks, fire and building requirements, intended use, and available budget all shape whether a detached ADU, attached unit, garage conversion, or addition is the better direction.
The City of Modesto outlines an eight-step path from the initial site plan and planning advice through permit review, construction, and inspections. Supreme Pro Builders can coordinate the approved construction scope from preconstruction and permitting through the build, finish work, and final walkthrough.
What the scope can include
Construction details coordinated under one contractor.
Garage conversions, in-law suites, and junior ADU scopes
Bedroom, bathroom, living-room, and primary-suite additions
Site planning, access, utilities, and existing-condition review
Foundation, framing, roofing, windows, doors, and interiors
Permit, inspection, trade, and construction coordination
A practical fit
Built around the outcome you need.
Multigenerational living
Create a more independent space for family while keeping loved ones near the primary home.
Rental or flexible space
Plan a separate dwelling around long-term household goals without assuming a specific rent, return, or approval outcome.
Home expansion
Add bedrooms, bathrooms, offices, living areas, or a larger primary suite when a connected addition is the better fit.
ADU planning focus
Choose the ADU path that fits the property.
The right starting point depends on the site, existing structure, utilities, intended use, plans, and current City requirements. These are distinct construction paths—not interchangeable labels.
Detached ADUs
A separate backyard dwelling needs coordinated placement, access, foundation, utility routing, structure, envelope, interiors, and inspections.
Garage conversions
An existing garage must be evaluated for foundation and floor conditions, ceiling height, structure, insulation, openings, utilities, egress, and the proposed layout.
Attached ADUs
An attached unit connects new living space to the main home and requires a clear plan for structure, fire separation, utilities, privacy, and circulation.
Junior ADUs
A JADU is created within a single-family residence and follows its own size, layout, and facility rules under current California and local requirements.
Room additions
A bedroom, bathroom, living area, or primary-suite expansion may solve the space need without creating a separate dwelling unit.
Plans & site feasibility
Custom plans, available pre-approved plan options, and site-specific constraints should be compared before the construction scope is finalized.
How the project moves
Clear phases. Connected decisions.
The exact path depends on scope and site conditions, but the fundamentals stay consistent from preconstruction through the final walkthrough.
- 01
Property & goal review
We discuss who the space is for and review the lot, existing structures, access, utilities, conditions, and known constraints.
- 02
Planning direction
The team compares the practical fit of a detached unit, conversion, attached ADU, JADU, or home addition before the scope is locked.
- 03
Plans, engineering & permit
Site plans, design documents, engineering, energy requirements, permit submittal, trade scopes, and construction sequencing are coordinated as applicable.
- 04
Build & inspections
Site work, structure, building systems, envelope, interiors, and required inspections are coordinated through completion.
- 05
Closeout & walkthrough
Required final inspections, punch work, documentation, final details, and the owner walkthrough complete the approved construction scope.
Start with the property
Compare a garage conversion and detached ADU.
Review the actual space, lot, utilities, permit path, and project goal before selecting an ADU construction approach.
Review the City of Modesto’s current ADU process and plan options →
Read California HCD’s March 2026 ADU Handbook →
Planning the budget? Use the site’s project financing calculator or review all Modesto construction services.
Project questions
ADUs & Home Additions FAQs
Do you build attached and detached ADUs in Modesto?
Yes, depending on project fit. Feasibility depends on the property, current zoning and building requirements, utilities, access, plans, intended use, and approved scope.
Can an existing Modesto garage become an ADU?
A garage conversion may be possible, but the existing structure, foundation and floor, ceiling height, openings, insulation, utilities, egress, proposed layout, and current approval path must be reviewed.
Does Modesto offer pre-approved ADU plans?
The City says Stanislaus County and participating cities developed detached ADU plan options that are available to property owners. A plan option still needs to be evaluated against the actual lot, site work, utilities, finishes, and current permit requirements.
What is Modesto's ADU Express Program?
The City describes ADU Express as an appointment-based coordinated plan review for qualifying, complete ADU and JADU submittals. Eligibility and current scheduling should be confirmed directly with the City before relying on that path.
What changes the cost of an ADU or garage conversion?
The plan type, size, existing conditions, foundation and structure, utility distances and upgrades, site access, design and engineering, permit requirements, finish level, and necessary site work can materially change the construction cost. A property-specific review is needed for a responsible estimate.
Do you coordinate ADU permits and inspections?
Supreme Pro Builders can coordinate applicable permit and inspection work as part of an approved construction scope. The exact responsibilities and City requirements should be documented before the build begins.
Start the conversation
Tell us what you want to build.
Share the property location, project type, and a few details. We’ll follow up to learn more and discuss the next step.
Prefer to call?510-725-5120