Add a complete secondary home that connects naturally to the primary residence. Builtech plans the structure, circulation, privacy, utilities, fire separation, architecture, and permit package as one coordinated addition.
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IS AN ATTACHED ADU RIGHT FOR YOU?
When Attached ADUs Are the Right Fit
An attached ADU can work well when yard area is limited, when the new unit should share a roofline or wall with the main home, or when the family wants close physical proximity without giving up a separate entrance and independent living space. The project should be treated as both an ADU and a major addition because the new work affects the existing structure, envelope, utilities, and daily life inside the home.
IDEAL FOR
An in-law suite close to the primary household
A side or rear addition on a constrained lot
A unit that shares selected utility routes with the main home
An addition designed to match an existing architectural style
A future rental that still feels integrated with the property
FROM FEASIBILITY TO CLOSEOUT
Builtech’s Integrated Attached ADU Process
The process is organized around investigating the existing home before locking the floor plan, so structural and utility conditions are reflected in the design. Each stage has a defined decision, deliverable, and owner responsibility so design, permitting, pricing, and construction remain aligned.
01
Feasibility
Review the property, goals, ADU type, site constraints, utilities, access, budget, and schedule before committing to a design path.
02
Concept Design
Test placement, floor plan, massing, privacy, materials, and construction approach. Select a preferred concept and record unresolved questions.
03
Engineering + Permits
Coordinate architecture, structure, energy, utilities, fire, and site documents; submit a complete package and manage agency comments.
04
Preconstruction
Finalize scope, price, selections, permit conditions, utility tasks, schedule, long-lead materials, financing, and site logistics.
05
Construction + Inspections
Manage site work, structure, enclosure, systems, finishes, quality control, inspections, safety, communication, and changes.
06
Closeout
Complete final inspections, punch work, utilities, warranties, manuals, permit records, owner orientation, and project documentation.
PROPERTY FEASIBILITY
Property and Feasibility Review
Before design begins, Builtech evaluates the property as a complete system. The review identifies what appears feasible, what requires confirmation, and which decisions have the greatest effect on cost, schedule, and approval.
DESIGNED AROUND HOW YOU’LL LIVE
Design Priorities for a Better Attached ADU
A successful attached ADU should work as a home first. The design must balance efficient area, privacy, daylight, storage, utilities, durability, and the relationship between the ADU and the primary residence.
CONSTRUCTION + BUILDING SYSTEMS
Construction and Building-System Strategy
The design team must understand how the addition connects to the existing foundation, framing, roof, weather barrier, drainage, and energy systems. Structural openings, shared walls, attic conditions, and existing unpermitted work can materially affect scope. Early investigation reduces the risk of discovering major conflicts after demolition begins.
Existing Foundation + Framing
Review how the new work connects to existing load paths, framing, foundations, and structural openings.
Roof + Weather Barrier
Shared-Wall Assemblies
Utilities + Energy Systems
How Builtech Evaluates the Right Building System
Total Installed Cost
Compare complete system cost, not just a material price.
Site Access
Confirm that equipment, crews, and delivery routes are practical for the property.
Structural Requirements
Align the selected approach with the existing home and engineering needs.
Energy Performance
Review insulation, air sealing, glazing, mechanical systems, and applicable requirements.
Fire Exposure
Evaluate assemblies against site exposure and applicable fire requirements.
Moisture Management
Coordinate drainage, weather protection, and durable wall assemblies.
Trade Availability
Confirm qualified labor and specialty trades can support the selected approach.
Permitting
Evaluate integration with required documentation and agency review.
Schedule
Plan lead times, sequencing, inspections, and occupied-home logistics.
Long-Term Maintenance
Consider serviceability, finishes, durability, and owner expectations.
PERMITS + COORDINATION
Permitting, Utilities, and Code Coordination
Attached ADUs are generally reviewed ministerially when they meet applicable objective standards, but the permit set still needs coordinated architectural, structural, energy, fire-life-safety, and utility information. Builtech also reviews how the project affects the primary home’s egress, natural light, mechanical systems, and code compliance.
Existing-Home Review
Document conditions that may affect access, egress, natural light, mechanical systems, and the proposed addition.
Architectural + Structural Set
Coordinate plans, elevations, sections, structure, and other supporting project information.
Energy + Building Systems
Align envelope, mechanical, electrical, plumbing, and applicable energy documentation.
Utilities + Infrastructure
Evaluate service capacity, routing, connection requirements, and property-specific constraints.
Fire + Life Safety
Address shared conditions, openings, separation, access, and life-safety requirements.
Agency Comments
Manage applicable comments while keeping the package coordinated through review.
BUDGET + SCHEDULE
A reliable attached ADU budget is based on the property and project scope—not a headline price per square foot. The extent of structural alteration, roof and foundation tie-ins, utility relocation, protection of occupied areas, acoustic and fire-separation assemblies, and exterior matching can all influence cost and schedule.
RELATED ADU SERVICES
START WITH YOUR PROPERTY
Find Out What Your Property Can Support
Tell Builtech about your property, goals, intended ADU use, preferred project approach, budget range, and timing. The first conversation will identify the information needed to evaluate feasibility and define the most useful next step.
ATTACHED ADU FAQs
Frequently Asked Questions About Attached ADUs
Get answers to common questions about attached ADU requirements, shared walls, size, occupancy, and independent building systems.
Can an attached ADU share a wall with the main house?
Can an attached ADU be more than 50 percent of the main home’s area?
Will construction require us to move out?
Can the attached ADU have its own HVAC and electrical panel?
What does Builtech review during an attached ADU feasibility study?
How are permits handled for an attached ADU?
What affects the budget for an attached ADU?
Can an attached ADU use shared utilities?
What is Builtech’s process for designing and building an attached ADU?