More home.
Same address.
Room additions, second stories, and structural expansions — permitted, engineered, and built to seamlessly match your existing home.
Room Additions
A room addition is one of the most impactful investments you can make in your home. Adding a master suite, a home office, a second story, or an expanded living area can transform how your family uses your space — without the cost and disruption of moving.
Additions require precise structural engineering, careful permit management, and skilled finish carpentry to ensure the new space matches the existing home seamlessly. At Arc, we handle all three with our in-house team.
From single-room additions to full second-story builds, we've completed projects ranging from 200 to 2,000 sq ft across Los Angeles. Every project gets a dedicated project manager and full Arc Studio access.
Our process.
Everything you need
to know.
We use the same roofing, siding, trim profiles, and interior finishes as your existing home. Our finish carpenter specializes in seamless transitions.
Yes. Any addition modifying load-bearing walls or adding roof and floor loads requires a licensed structural engineer — included in our scope.
A single-room addition: 12–18 weeks after permits. A second story: 20–28 weeks.
In California, only the added square footage is reassessed — not the entire home. The increase is typically modest relative to the value added.
Most single-story homes can accommodate a second story with proper engineering. We assess the existing foundation and framing before committing.
Ready to build your
addition project?
Configure your project online and get a realistic budget estimate before your first call with us.