ADU Structural Engineering & Design Services
Transform your property with a professionally engineered Accessory Dwelling Unit. Our licensed structural engineers specialize in ADU design throughout California, providing PE-stamped plans that meet state and local requirements.
What is ADU Engineering?
Accessory Dwelling Units (ADUs) are additional residential units on single-family properties. California law encourages ADU development, but structural engineering is required for all ADUs to ensure safety and code compliance. We specialize in ADU structural engineering, navigating complex state ADU laws, local building codes, and HOA requirements.
Why Choose Our ADU Engineering Services
Expert knowledge of California ADU laws and local requirements
Cost-effective foundation and structural designs for ADUs
Experience with all ADU types (detached, attached, garage conversion, JADU)
Navigate HOA approval processes with required documentation
Fast turnaround to meet ADU streamlined permitting timelines
Coordinate with architects or provide preliminary layout assistance
Understand ADU-specific challenges (setbacks, height limits, utilities)
What We Provide
Comprehensive adu engineering services with complete documentation
Complete ADU Structural Design
Foundation design, structural framing, roof structure, and lateral force-resisting system specifically optimized for ADU construction.
Foundation Engineering
Cost-effective foundation design based on soil conditions, ADU size, and site constraints. We design conventional foundations, post-tension slabs, or specialized systems as needed.
Code Compliance Analysis
Navigate complex intersection of state ADU law, California Building Code, local amendments, and HOA requirements. Ensure your ADU meets all applicable codes.
HOA Documentation
Provide structural drawings, calculations, and documentation required by HOAs. We understand HOA review processes and design to meet their requirements.
Garage Conversion Engineering
Specialized structural analysis for converting existing garages to living space including floor system evaluation, new openings, and accessibility requirements.
Site Constraint Solutions
Creative structural solutions for challenging sites including small lots, setback issues, slopes, easements, and existing structure integration.
How It Works
Our streamlined process for adu engineering
ADU Feasibility Consultation
Review property for ADU feasibility, discuss ADU types, review local requirements, and provide guidance on structural approach and estimated costs.
Site Assessment
Evaluate site conditions, setbacks, easements, utilities, soil conditions (or coordinate geotechnical report), and existing structures affecting ADU design.
Floor Plan Coordination
Review or assist with ADU floor plan layout considering structural efficiency, building code requirements, and site constraints.
Foundation Design
Design ADU foundation based on soil report, building loads, and site conditions. Optimize for cost while meeting code requirements.
Structural System Design
Design framing system, roof structure, and lateral force-resisting system. Coordinate with mechanical, electrical, and plumbing requirements.
Drawing & Calculation Package
Produce complete structural drawings and calculations package with PE stamp ready for permit submittal and HOA review.
Permit & HOA Support
Respond to building department plan check corrections and provide additional documentation for HOA approval if needed.
Construction Phase Support
Available for contractor questions, foundation inspection, and construction support to ensure proper implementation of structural design.
Common Applications
We provide adu engineering for a wide range of projects
Cost Information
Transparent pricing for your project
Typical Range:
$3,000 - $8,000 for most ADUs; garage conversions $3,000-$5,000; hillside ADUs $6,000-$10,000+
Factors Affecting Cost:
- ADU type (detached, attached, garage conversion, JADU)
- Square footage
- Number of stories
- Site conditions and slope
- Soil quality and foundation requirements
- Setback and site constraints
ADU structural engineering fees depend on ADU type, size, and site complexity.
Timeline
What to expect for your project
Design Phase
2-3 weeks for typical ADUs; 3-4 weeks for complex sites
Permitting
2-6 weeks (ADUs benefit from streamlined review)
Total Timeline
4-10 weeks typical from engagement to permit-ready plans
Timelines vary based on project complexity, jurisdiction requirements, and information availability. We provide detailed schedules during consultation.
Frequently Asked Questions
Common questions about adu engineering
Do I need a structural engineer for an ADU?
Yes, California requires all ADUs to have structural plans prepared and stamped by a licensed Professional Engineer or Architect. This includes detached ADUs, garage conversions, and JADUs. Structural engineering ensures your ADU is safe and complies with building codes.
How much does ADU structural engineering cost?
Typical ADU structural engineering costs $3,000-$6,000 for standard detached ADUs, $3,000-$5,000 for garage conversions, and $5,000-$8,000 for second-story ADUs or complex sites. Hillside properties or challenging soil conditions may cost more. We provide free consultations and detailed quotes.
How long does ADU structural engineering take?
Most ADU structural engineering takes 2-3 weeks from receiving architectural plans to delivering stamped structural drawings. Complex sites or hillside ADUs may take 3-4 weeks. We can expedite for urgent timelines. Total time from consultation to permit-ready plans is typically 4-6 weeks.
Can you help with ADU floor plan design?
While we focus on structural engineering, we can provide preliminary layout guidance and feasibility input. We work seamlessly with architects or can recommend design professionals. Many clients use our structural expertise to inform their ADU layout before finalizing architectural plans.
Do you handle HOA requirements for ADUs?
Yes, we regularly work with HOAs and provide all documentation they require including structural drawings, calculations, material specifications, and elevation drawings. We understand HOA review processes and design ADUs to meet their architectural and structural standards.
Can you convert my garage to an ADU?
Yes, garage conversions are one of our specialties. We evaluate the existing garage structure, design necessary modifications, address floor height requirements, design new openings for windows/doors, and ensure the converted space meets residential building code. Most garages can be successfully converted to ADUs.
What if I have a sloped lot or challenging site?
We specialize in challenging sites including slopes, tight setbacks, easements, and difficult access. We design appropriate foundation systems (stepped foundations, retaining walls, pier foundations) and work with geotechnical engineers when needed. Hillside ADUs are more complex but very achievable.
Do you coordinate with prefab/modular ADU companies?
Yes, we work with prefab and modular ADU manufacturers to design foundations for their units. We review manufacturer specifications and design site-specific foundations meeting building code and manufacturer requirements. Most prefab ADUs still require site-specific foundation engineering.