




500 SF ADU Floor Plan
A compact concept for guest accommodations, smaller rental units, or efficient backyard infill.
CA Licensed · 99% Permit Approval
Licensed architects and structural engineers for ADU design, home additions, remodeling, wall removal, and permits. Accurate, permit-ready plans with a 99% approval rate across California.

By the Numbers
Monthly Active Projects
Projects Delivered
Permit Approval Rate
Professional Team Members
Trust & Collaboration
Our architectural and structural plans are consistently approved across California — from Northern to Southern cities. With deep familiarity of local building codes, we help homeowners avoid rejections, shorten review cycles, and secure permits with confidence.
All featured projects are real, city-approved plans.
Our Services
Comprehensive design and construction solutions for residential and commercial projects, delivered with expertise and attention to detail.

Custom Accessory Dwelling Unit designs that maximize your property value while maintaining aesthetic harmony.

Remove load-bearing walls to create more space in your home.

Add extra space to your home with a new room or extension.

Transform your home with expert kitchen, bathroom, and living room remodeling.

Secure your building permits with our 100% approval rate and complete regulatory compliance guidance.

Expert foundation inspection with detailed structural reports to ensure safety and long-term stability.
ADU Floor Plans
Three concept floor plans — from a compact 500 SF studio to a 1,200 SF family-ready layout. Each includes a floor plan and 3D renderings so you can picture the space before committing.





A compact concept for guest accommodations, smaller rental units, or efficient backyard infill.





A balanced concept that begins to separate living, cooking, and resting zones more clearly.





A mid-size concept that feels more complete for long-term use without becoming oversized.





A comfort-focused concept for owners who want an ADU that feels closer to a small home.
These are concept layouts. We adapt the final plan to your lot, setbacks, and city permit path.
Why Choose Us
We’re not just another design firm — we’re the most-reviewed architecture firm on Thumbtack, completing 2–3 projects every week across California.
The highest-rated and most-reviewed architecture firm on Thumbtack in California — 500+ verified reviews and a 4.9★ rating from real homeowners.
We give you the complete, all-inclusive price before you commit — no lowball estimates, no change-order surprises. Just one honest number you can plan around.
We complete 2–3 projects of the same type every single week. That’s more hands-on experience in one month than most firms accumulate in a year.
We connect you with vetted, licensed contractors we work with repeatedly — no vetting required on your end, no coordination gaps between design and construction.
Share your project details and we respond within 1 business day with a complete, all-inclusive quote. No ‘I’ll need to come see it first,’ no hidden fees added later.
Licensed architects and structural engineers with deep knowledge of California codes, city-specific requirements, and a 99% permit approval rate across the state.
Our Process
Our process is designed to be transparent and efficient, delivering a complete one-stop service from design to final permit approval.
Share your project details and get a complete, fixed-price quote — full scope, full cost, no vague estimates.
Precise measurements and site evaluation for accurate project planning.
Creating detailed plans and visualizations to bring your vision alive.
Navigating complex approval processes to ensure code-compliant construction.
Ongoing guidance and contractor coordination throughout the building process.
Client Testimonials
Ranked #1 on Thumbtack based on verified reviews from homeowners who relied on our architectural and structural engineering services.
We wanted to build an ADU in our backyard but had no idea where to start. Mason walked us through zoning, setbacks, and the permit timeline. The plans were approved on the first submission—way faster than we expected.
Removing our load-bearing wall seemed risky, but Mason explained the beam options and provided engineering calcs the city approved right away. Our open-concept kitchen is exactly what we dreamed of.
We remodeled our entire first floor—kitchen, living room, and bathrooms. Cecilia Home handled all the structural drawings and coordinated with our contractor. The permit process was surprisingly smooth.
We wanted to build an ADU in our backyard but had no idea where to start. Mason walked us through zoning, setbacks, and the permit timeline. The plans were approved on the first submission—way faster than we expected.
Removing our load-bearing wall seemed risky, but Mason explained the beam options and provided engineering calcs the city approved right away. Our open-concept kitchen is exactly what we dreamed of.
We remodeled our entire first floor—kitchen, living room, and bathrooms. Cecilia Home handled all the structural drawings and coordinated with our contractor. The permit process was surprisingly smooth.
Adding 800 sq ft to our home felt overwhelming, but Mason's team made it manageable. From foundation plans to the final permit stamp, every detail was covered. We couldn't be happier with the result.
After noticing cracks in our foundation, we called Cecilia Home for an inspection. Mason was honest—he explained which cracks were normal for older Bay Area homes and which needed attention. No pressure, just solid advice.
As a general contractor, getting permits approved quickly is critical. Mason's team delivers accurate plans and handles city comments fast. Our projects run smoother when Cecilia Home is involved.
Adding 800 sq ft to our home felt overwhelming, but Mason's team made it manageable. From foundation plans to the final permit stamp, every detail was covered. We couldn't be happier with the result.
After noticing cracks in our foundation, we called Cecilia Home for an inspection. Mason was honest—he explained which cracks were normal for older Bay Area homes and which needed attention. No pressure, just solid advice.
As a general contractor, getting permits approved quickly is critical. Mason's team delivers accurate plans and handles city comments fast. Our projects run smoother when Cecilia Home is involved.
Converting our garage into an ADU for my mother-in-law was the perfect solution. The design maximized every square foot, and the city approved the plans with no corrections. Now she has her own private space.
Our 1920s bungalow needed seismic retrofitting before we could refinance. Mason provided the engineering report and retrofit plans the city required. The whole process was faster than our bank deadline.
We hired Cecilia Home for our kitchen remodel permit drawings. Mason's team was responsive and fixed minor city comments within days. Compared to other engineers we've used, their turnaround time is exceptional.
Converting our garage into an ADU for my mother-in-law was the perfect solution. The design maximized every square foot, and the city approved the plans with no corrections. Now she has her own private space.
Our 1920s bungalow needed seismic retrofitting before we could refinance. Mason provided the engineering report and retrofit plans the city required. The whole process was faster than our bank deadline.
We hired Cecilia Home for our kitchen remodel permit drawings. Mason's team was responsive and fixed minor city comments within days. Compared to other engineers we've used, their turnaround time is exceptional.
FAQ
Find clear answers about our services, timelines, process, and how we help you move from design to permit approval smoothly.
Haven't found what you're looking for?
We provide architectural and structural design for ADUs, home additions, interior remodeling, wall removals, foundations, seismic retrofits, and permit-ready plans. We also handle all building permit submissions and revisions until approval.
We start with a free consultation, then complete your preliminary plans within one week. Final stamped plans typically take 2–3 weeks. Throughout the process, we provide clear communication, 3D visualization when needed, and full support through city review.
Our pricing is based on project scope and complexity. We offer transparent, fixed-price packages for common services such as ADUs and additions, and provide detailed quotes during your free consultation with no hidden fees.
Preliminary plans are completed in 1 week, and final plans take 2–3 weeks. City review timelines vary by city, but ADU permits typically take 2–3 months. We keep you updated throughout each stage.
Yes. We help you optimize your design based on your budget and provide cost-conscious recommendations while maintaining structural safety and code compliance.
Simply contact us to schedule a free consultation. We’ll review your project goals, timeline, and budget, then prepare a customized proposal. Virtual meetings are available.