ADU Builder · Calabasas
A guest house for the in-laws, a suite for your parents, or a detached ADU that earns its keep. Calabasas lots have the room. We permit through the city and build to estate standards.
ADU Builder in Calabasas
Calabasas lots run big, some of the largest in the region, and most have room for a second, smaller home. Maybe your parents move in, close but not underfoot. Maybe it becomes the guest house your property always implied. We build detached ADUs and multigenerational suites to estate standards, because on Calabasas land, every square foot counts.
Athenian Builders Group is a licensed California general contractor (CSLB #1045030) that designs, permits, and builds ADUs across Calabasas with its own crews. You approve a fixed, itemized price and a firm timeline before we start, and every build carries a 2-year workmanship warranty. See our full ADU construction services.
Permits
Calabasas is its own incorporated city, so ADU permits go through the City of Calabasas building department rather than LADBS. We handle the drawings, the submittal, and every inspection, so the process stays on our plate, not yours.
Transparent Pricing
Real 2026 ranges for the Los Angeles area, by ADU type. Size, site conditions, and finishes decide where you land. After a free on-site visit, you get a fixed, itemized price.
| ADU Type | Typical Size | Typical Cost (2026) |
|---|---|---|
| Garage Conversion | 300–500 sq ft | $100k – $180k |
| Junior ADU (JADU) | up to 500 sq ft | $90k – $160k |
| Attached ADU | 400–800 sq ft | $180k – $320k |
| Detached New-Build | 500–1,200 sq ft | $250k – $450k |
Typical ranges for 2026, not quotes. Financing is available for qualified homeowners. See remodel financing options. Considering a smaller in-home unit? See our Junior ADU page.
Estimated project cost
Why Athenian
Most “ADU builders” are design shops or brokers who sub the construction out. We are a single self-performing team: we design it, pull the permits, and build it with our own crews. That means one point of contact, a fixed itemized price before we start, a firm timeline in writing, and a written 2-year workmanship warranty on everything we build in Calabasas.
Questions
Yes. We design and build detached ADUs and guest houses across Calabasas, including the gated and hillside communities, and our own crews do the work.
Calabasas is its own city, so permits are issued by the City of Calabasas building department, not LADBS. We prepare the plans, file them, and manage inspections through sign-off.
Type and size drive the number. A garage conversion typically runs $100k–$180k, while a detached new-build lands between $250k–$450k. After a free on-site walkthrough, you get a fixed, itemized price, and that number holds.
Most of our ADUs finish in 3 to 5 months, depending on type, size, and city review times. You approve a firm timeline in writing before construction starts.
Start with a free on-site feasibility visit and a fixed, itemized price for your Calabasas ADU. Call (310) 857-2520. You’ll know exactly what it costs before we break ground.
Takes about a minute. We reply the same business day and set up a free on-site visit.
