Home Addition
Permit-Ready California Home Addition Design & Engineering
From space planning and new room layouts to structural engineering, foundation design, and permit submittal—we provide complete home addition design solutions that are safe, compliant, and engineered for smooth city approval.
Our Stats
California Trusted Architectural & Structural Engineering
Years of Experience
Projects Delivered
Permit Approval Rate
Professional Team Members
Cecilia Home provides licensed architectural and structural engineering services for ADUs, additions, remodeling, wall removals, and permit-ready plans. We make the process simple, clear, and stress-free.
With 20+ years of experience, 2,000+ completed projects, and a 95% approval rate, our California-registered engineers deliver accurate, code-compliant designs trusted by homeowners statewide.
Trust & Collaboration
Home Addition Plans Approved Across California Cities
Our architectural and structural home addition plans are consistently approved by building departments across California. With deep expertise in load-bearing analysis, foundation design, and California Building Code requirements, we help homeowners reduce corrections, avoid rejections, and secure faster permit approval for new bedrooms, second-story additions, extensions, and more.
All Featured Projects Are Real, City-Approved Plans
Why You Need This
Why Careful Planning Is Critical for Home Additions
Additions impact zoning, setbacks, structural loads, and overall property value—making proper planning essential for fast approval and safe construction.
Challenges Homeowners Often Overlook
- Setback and lot coverage violationsCities have strict rules—violations cause rejection or redesign.
- HOA style and material restrictionsMany communities require pre-approval and matching architectural styles.
- Insufficient structural capacityAdding second floors or extensions requires beam, shear wall, and foundation upgrades.
Benefits of Proper Addition Planning
- Maximize allowable buildable areaWe analyze zoning to help you build as much as legally possible.
- Reduce city correction cyclesPlans aligned with local code lead to faster approvals.
- Ensure long-term structural safetyAll load paths, shear walls, and foundations engineered to code.
Why Choose Cecilia Home
- Full zoning & feasibility reportsKnow EXACTLY what you can build before spending money.
- Architectural + structural integrationDesigns that are beautiful, practical, and fully buildable.
- Thousands of CA homes expanded successfullyExperience with hillside lots, HOAs, older homes, and complex geometry.
Our Features
Why Choose Cecilia Home?
Licensed, experienced, and trusted across California—we deliver precise designs, clear communication, and reliable results for every project.
PROFESSIONAL EXPERTISE
Licensed architects and engineers with deep knowledge of California codes, ensuring accurate, compliant, and build-ready designs.
CLIENT-CENTERED APPROACH
Clear communication and personalized guidance at every step, ensuring your vision stays at the center of the project.
COMPREHENSIVE SOLUTIONS
From design to permit approval, we provide complete, end-to-end services that save you time and streamline your project.
QUALITY ASSURANCE
All plans meet California building standards, with rigorous checks to ensure safety, accuracy, and long-term performance.
FAST & EFFICIENT DELIVERY
Our optimized design workflow allows us to deliver complete, permit-ready plans in as fast as 7 days—without compromising quality.
LOCAL EXPERIENCE
Expert understanding of California’s building styles, climate needs, and local city requirements for successful permits.
Addition Design
Home Addition Architecture & Engineering
California-compliant home addition drawings engineered for structural safety, code adherence, and fast permit approval.
Rear Addition Expansion
Architectural and structural plans for extending your home into the backyard, adding new living space while meeting zoning and setback requirements.
Second-Story Addition
Full structural engineering for safely adding a new upper level — including load path redesign, shear wall upgrades, and complete framing plans.
Garage Conversion + Expansion
Convert your attached garage into livable space and extend the footprint with a front or side addition. Includes architectural plans and all required structural engineering.
Interior Expansion & Reconfiguration
Push out existing exterior walls and reconfigure interior layouts to gain usable space. Includes structural design for new openings, beams, and foundation upgrades.
Our Process
Our Process
Our process is designed to be transparent and efficient, delivering a complete one-stop service from design to final permit approval.
Guidance for your project
Free Consultation
Expert advice on your project needs, budget considerations, and permit requirements.
On-Site Assessment
Precise measurements and site evaluation for accurate project planning.
Design Development
Creating detailed plans and visualizations to bring your vision alive.
Permit Acquisition
Navigating complex approval processes to ensure code-compliant construction.
Construction Support
Ongoing guidance and contractor coordination throughout the building process.
Client Testimonials
Trusted by California Homeowners
Ranked #1 on Thumbtack based on verified reviews from homeowners who relied on our architectural and structural engineering services.
Cecilia Home designed our complete home renovation, explained everything clearly, and delivered detailed plans. Honest, professional, and fairly priced—our HOA now knows exactly how to proceed.
View Verified ReviewTrudy M.
Home Remodeling
Mason delivered exactly what I needed—professional, responsive, and great value. Clear communication throughout the process. I'll rely on him for all future remodeling projects.
View Verified ReviewJoanne D.
Home Remodeling
Mason responded instantly and offered honest guidance on whether my garage conversion would pass city review. Knowledgeable, direct, and trustworthy—I look forward to working with them again.
View Verified ReviewJasper T.
ADU Design
I appreciated their honesty. They explained that my foundation cracks were common in the Bay Area and didn't push unnecessary work. Professional, transparent advice I could trust.
View Verified ReviewArturo S.
Structural Engineering
As a general contractor, I value teams who are responsive and accurate. Cecilia Home delivered clear communication, timely plans, and over-the-counter approval. I highly recommend them.
View Verified ReviewKevin V.
Building Permit Services
Mason gave detailed structural guidance for removing our load-bearing wall, including safety considerations. Quick responses and practical advice that helped us comply with local regulations.
View Verified ReviewJackson B.
Wall Removal
FAQ
Frequently Asked Questions
Find answers to common questions about home addition design, engineering, and permit approval.
Yes. Any expansion of your home's footprint or addition of new rooms requires a building permit. We prepare complete architectural and structural plans for city submittal.
Absolutely. Second-story additions require comprehensive load analysis, shear wall design, new beam and column calculations, and potential foundation upgrades. Our licensed engineers prepare all required structural documents.
Initial concepts can be ready within 5–7 days. Complete architectural and structural plans typically take 2–4 weeks depending on the size and complexity of the addition.
Yes. We submit all home addition plans on your behalf and handle correction responses until your permit is approved.
Yes. We verify zoning constraints, lot coverage, setbacks, and height limits to ensure your home addition complies with local regulations before design begins.
Yes. We design home additions throughout California and understand the specific plan review standards of many cities statewide.