Custom Homes
Ground-up and hillside custom residences — architect-led or full design-build.
California Custom Homes · ADUs · Remodels
Built at a Price We
Lock Before Permits
Ground-up homes, ADUs, remodels & multifamily across California — with a fixed price locked before permits. No surprises, no cost creep.
★ Price-Lock Guarantee · Free consultation · Mon–Sat 8–8
Services
What We Build in California
From ground-up custom homes to backyard ADUs — one licensed team, one price locked before permits.
ADUs & Garage Conversions
Add space, value and rental income — by right under California law.
Remodels & Additions
Kitchens, baths, whole-home remodels and room additions.
Multifamily & Commercial
Ground-up and value-add multifamily, tenant build-outs and mixed-use.
Instant Tool · Free
Can You Build On Your Lot?
Enter your California address and get an instant readout — we locate your property and show what California law lets you build (ADUs, JADUs & more), right now, before you ever pick up the phone.
Free instant check · powered by OpenStreetMap · no account, no cost.
Parcel Feasibility
Enter your address — see what you can build, instantly.
Our Work
What We Build
The kind of work we take on across California. Filter by type.
Residential
Residential
Interior
Commercial
Commercial
Commercial
ADU
ADU
ADU
Investment
Investment
Investment
Transformations
Before & After
Drag to reveal the transformation.
Before
After
How It Works
From Discovery to Handover
A structured, predictable path — no surprises, no cost creep.
1
Discovery
Free consult, goals, feasibility.
2
Design
Plans, selections, fixed scope.
3
Price Lock
Committed price before permits.
4
Build
Craftsmanship, progress updates.
5
Elevate
Walkthrough, warranty, handover.
Affordability
Estimate Your Monthly Payment
Slide to see an estimated payment. Ask us about $0-down and CalHFA ADU programs.
Answers
Frequently Asked
Straight answers to the questions we hear most.
Can I build an ADU on my California property?
Almost every California residential lot can add at least one ADU by right under state law (AB 68 / SB 13). Detached ADUs can be up to about 1,200 sq ft with only 4-ft side and rear setbacks, plus an optional Junior ADU up to 500 sq ft inside the home. Try our free Can You Build On Your Lot? tool for an instant readout — including your exact lot size in many counties.
What is the Atrium Price-Lock guarantee?
We commit to your project price in writing before plans go to the city — so there's no mid-project cost creep. Change orders only happen with your approval. It's the single biggest protection against the cost overruns homeowners fear most.
What does Atrium build?
Custom homes, ADUs and garage conversions, interior remodels, commercial and tenant build-outs, and ground-up and value-add multifamily — across California.
How fast can an ADU be approved?
California law requires ministerial ADU approval within 60 days of a complete application, with no owner-occupancy requirement. We handle the plans, permitting, and inspections for you.
Do you help with financing?
Yes. Use our on-site payment estimator to model a monthly payment, and ask us about $0-down options and California CalHFA ADU programs. We'll point you to the right path for your project.
Where do you work?
We build across California. Enter your address in the lot tool and we'll confirm your location and what state law allows on your parcel.
Let's Talk
Start the Conversation
A project, an opportunity, or a partnership in mind? Reach out — free consultation, no pressure.