Los Angeles County
Los Angeles Building Designer
for Permit-Ready Plans
Decade-proven expertise in residential building design. Over 1,500 approved projects across Los Angeles County and Orange County: custom homes, ADUs, additions, remodels, and 2 to 4 unit residential.
Scroll
About the Studio
Built on a Decade
of Delivering
Design 1 Studio has 1,500+ approved projects since 2015. Since then, we’ve been the team that property owners and investors call when the project has to be done right, and done completely. We don’t walk away. We don’t hand off. We see every single project through from first concept to final approval.
With over 1,500 approved projects behind us, we bring the kind of experience that can’t be faked or fast-tracked.
Nathan Sewell founded Design 1 Studio in 2015 and has led more than 1,500 approved projects across Los Angeles County and Orange County: ADUs and garage conversions, additions and second stories, custom homes, Eaton Fire rebuilds, and the legalization of existing buildings. His work starts with the code. Before a line is drawn, he reads the zoning, the overlays, and the plan check history of the lot, and when a city issues a correction the code does not support, he answers it in writing and takes it to the State when he has to. Every plan set is coordinated with a licensed structural engineer and managed through permit issuance. Design 1 Studio works from Pasadena and Monrovia.
Design 1 Studio Inc. is a fully established, incorporated design firm with the track record, the expertise, and the staying power to prove it.
“We don’t start projects. We finish them.”
Our Work
A Decade of
Delivered Projects
From modern ADUs to Spanish Revival estates, every project reflects our commitment to thoughtful design and meticulous execution.
What We Do
Full-Scope Design
Services
From initial sketches to permit-ready construction documents, we handle every phase of the design process for residential projects throughout Los Angeles and Orange Counties.
Custom Home Design
Ground-up residential design for single-family homes, from modern minimalist to Mediterranean revival. Complete plan sets prepared for LA County permitting and construction.
ADU & Guest House Design
Drawing ADUs since 2017, the year the state reforms made them practical to permit. Garage conversions, detached units, and junior ADUs: we’ve done them all, hundreds of times over.
Duplexes, Triplexes & Fourplexes
Duplexes, triplexes, and fourplexes. We understand density, zoning, and how to maximize value on every square foot of your lot.
Home Remodels & Additions
Room additions, second stories, kitchen and bath redesigns, and whole-home renovations. We seamlessly blend new construction with existing structures.
Permit & Plan Check
We prepare complete construction document packages and navigate the plan check process with LA County, City of LA, and surrounding jurisdictions, with plan check support through issuance.
Plan Check Advocacy
When a city issues a correction the code does not support, we answer it in writing with the section that controls, request a formal determination, and take it to the State (HCD) when a city will not follow state ADU law.
ADU Specialists
Designing ADUs in
LA County
Since 2017
We have drawn ADUs since 2017, when the state reforms first made them practical to permit, and the plan sets have kept pace with every change since. Design 1 Studio was among the very first to specialize in Accessory Dwelling Units, and we’ve been at the forefront of every regulatory update since.
From 400-square-foot junior ADUs to two-story detached units, from garage conversions to new construction: we’ve designed hundreds of ADUs across virtually every city and jurisdiction in LA County. We know the setbacks, the height limits, the parking exemptions, and the utility requirements inside and out.
2017
Designing ADUs Since
Hundreds
ADU Projects Completed
Our Process
Start to Finish
Every project follows our proven four-phase process: a system refined over ten years and 1,500+ approved projects to eliminate guesswork and keep your build on track.
I
Consultation
We listen first. Free initial consultation to understand your vision and timeline.
II
Concept Design
Preliminary layouts, site plans, and design concepts developed in close collaboration with you. We refine until it’s exactly right.
III
Construction Documents
Complete, permit-ready plan sets, coordinated with licensed structural, mechanical, electrical, and plumbing engineers where required. Ready for submission.
IV
Permit & Beyond
We submit, we handle plan check corrections, and we support you through construction. We don’t disappear after the plans are drawn.
Our Promise
Every Project, Through Permit
Design 1 Studio was built to last. We’ve been here for ten years, we’ll be here for ten more, and every project we take on gets the full weight of our experience and commitment. Period.
We Finish What We Start
Every project. Every time. We don’t abandon timelines and we don’t leave clients hanging.
A decade navigating LA County’s building codes, zoning laws, and permitting processes. We know what gets approved and what doesn’t.
We’re Accountable
Incorporated. Insured. Established. We put our name on everything we produce because we stand behind the quality of our work.
Selected reviews
5.0 on Google, 55 reviews
★★★★★
Our previous designer abandoned our project mid-plan-check and we were stuck for three months with an incomplete addition in Sierra Madre. Design 1 Studio came in, reviewed everything, identified what needed to be fixed ... and resubmitted the whole package. Nathan personally managed it through corrections and we just got our permit.
★★★★★
We wanted to add a mother-in-law suite to our home in San Dimas. Design1 Studio came out, looked at the property, and within a week had preliminary designs for us to review. The final plans were beautiful and the city approved them with only one minor correction. Great experience from start to finish.
★★★★★
Garage conversion ADU in Covina. Permitted and rented. Nathan made it painless. Five stars.
Get Started
Let’s Build
Something
Ready to move forward? Whether you have a fully formed vision or just the seed of an idea, we’re here to help you develop it into a reality. Your first consultation is free.
Phone
Service Area
Los Angeles County and Orange County
Availability
Mon – Fri, 9am – 6pm
Weekends by appointment