Attached
Integrated into the main house and finished to the same standard — able to serve as living space day to day, or as a private self-contained unit.
ADU Development · Los Angeles
Built to the standard
of the main house.
Thornton Development Group designs, permits and builds accessory dwelling units across Los Angeles — most often as part of a larger development, and on select standalone projects.
How We Approach ADUs
Not a bolt-on. Part of the plan.
An ADU adds permitted, finished square footage to a property — a guest house, a rental unit, space for family, or simply more of what a lot can carry. California has made them meaningfully easier to permit than they once were.
Most of the ADUs we build are designed alongside a main residence from the start, so the two read as one property rather than a house with something added behind it. We also take on select standalone ADU projects where the site and scope are a fit.
There is no minimum project size. We quote each project on its own merits and will tell you honestly if it isn’t right for us.
Configurations
Four ways an ADU shows up in our work.
Detached
A separate structure on the lot, common on larger hillside and estate parcels where there is room to place it well.
Within multifamily
An ADU counted into the unit mix of a ground-up multifamily building, adding a home without expanding the envelope.
Entitled for later
Permitting a lot for future ADUs so the capacity exists whether or not it is built in the first phase.
Built & Building
ADUs in TDG projects.
Every project below is one we developed. Status is noted on each.
Attached · Completed 2026
“The Gonzaga Residence”Westchester · fully permitted attached ADU
Detached · Under Construction
“The Pyramid MCM”Hollywood Hills · detached 1,200 sq ft guest house
Detached · Completed
“The Apex HH”Outpost Estates · detached accessory dwelling unit
Detached · Completed
“The Macapa Oasis”Outpost Estates · detached accessory dwelling unit
Within Multifamily
“The Case V”North Hollywood · 3-bed / 3.5-bath ADU in the unit mix
Entitlement · Potential
“The Gardner II”Fairfax District · potential for two additional ADUs
A Closer Look
“The Gonzaga Residence” — a second home, built in.
The fully permitted attached ADU integrates into the house as a large family room, bedroom, and full bath — finished to the same standard as the main residence.
It can also be delivered as a private one-bedroom, one-bath unit with its own living area and kitchen: an in-law suite, a rental, a studio, a gym, or an office. Same structure, two very different uses, decided by whoever owns it.
Good Questions. Straight Answers.
Before you add one.
Do you build standalone ADUs, or only alongside a main house?
Both, though most of our ADUs are designed as part of a larger development. We take on select standalone ADU projects where the site and scope make sense. Send us the address and we’ll tell you either way.
Attached or detached — which is right for my lot?
It depends on lot size, setbacks, topography, and what you want the space to do. On larger hillside parcels a detached structure usually places better; on tighter flat lots an attached unit often makes more sense. That determination is part of the feasibility assessment.
Do you handle permitting?
Yes. Design, permitting, and construction are handled in-house, the same as our ground-up developments — so there is one point of accountability rather than a designer, an expediter, and a builder pointing at each other.
How long does an ADU take?
It varies with scope, site conditions, and city processing. We give a written estimate after reviewing the property. All timelines are estimates, not guarantees — actual schedules depend on scope, site conditions, city processing, and timely client funding and decisions.
Is the ADU covered by the TDG Builder Warranty?
Ground-up new construction carries the TDG Builder Warranty under California SB 800. Remodels and conversions are not covered; workmanship on those is governed by the applicable construction contract. See the TDG Builder Warranty page for full terms.
Wondering what your lot can carry?
Send us the address. We’ll come back with what the property supports, what it would cost, and what it should be worth.