ADU Guides

Project Walkthrough: A 1,188 Sq Ft Two-Story ADU in Rosemead, CA

The short version

This is a finished 1,188 sq ft detached two-story ADU in Rosemead, CA — 3 bedrooms, 2 full bathrooms, an open-plan kitchen and living area downstairs, and a loft, two view bedrooms and a private balcony upstairs. We designed and built it, and the 48-second walkthrough below shows every room. It’s a working example of how a two-story ADU fits a full family home onto half the footprint a single-story would need.

48-second walkthrough of the finished unit, filmed on handover day.

Project at a glance

LocationRosemead, CA (San Gabriel Valley, Los Angeles County)
TypeDetached two-story ADU, new construction
Size1,188 sq ft
Layout3 bedrooms, 2 full bathrooms, second-floor loft
FinishesEuropean flat high-gloss cabinets, quartz counters, stainless appliances, Kohler fixtures, glass showers, luxury vinyl plank flooring
ExtrasWalk-in closet, private balcony, city and mountain views

01Downstairs: one open room that lives large

Open floor plan living and kitchen area of a two-story ADU in Rosemead with staircase and luxury vinyl plank flooring
The whole ground floor reads as one space — kitchen, dining and living, with the stair tucked against the back wall.

The ground floor is a single open volume: kitchen, dining and living in one run, with big windows on the long wall so the space is lit from the side all day. In a footprint this size, walls are what make a home feel small — so downstairs has almost none. The stair is pushed to the rear wall where it borrows no living space, and a full bathroom sits on the ground floor, which matters more than it sounds: it means the downstairs can work for an aging parent or a guest who shouldn’t need stairs.

02The kitchen: flat-panel gloss and quartz

Two-story ADU kitchen with European flat high-gloss white cabinets, quartz counters, stainless steel range and marble-look backsplash
European flat high-gloss cabinets, quartz counters, stainless appliances, full-height marble-look backsplash.
Quartz counter and stainless farmhouse sink under a garden window in a Rosemead ADU kitchen
The sink gets the window — a small layout decision that changes how the kitchen feels every day.

The kitchen runs in a U against the back of the unit: European flat high-gloss cabinets, quartz counters, a full-height marble-look tile backsplash and stainless appliances, with a deep single-basin sink under its own window. These are the same finish decisions we walk through with every client — and a good example of how an ADU kitchen doesn’t have to feel like a compromise.

03Two real bathrooms, one on each floor

Downstairs full bathroom in a Rosemead ADU with frameless glass shower, rain head and floating vanity
Downstairs full bath: frameless glass shower with rain head and handheld, floating vanity.

Both bathrooms are full baths — no half-bath compromises. Downstairs gets a frameless glass shower with a rain head and a floating vanity; the second-floor bath is fitted with Kohler fixtures. Two full baths is what lets a 3-bedroom layout genuinely work for a family or for roommates, rather than just on paper.

04Upstairs: the loft in the middle

Second floor loft of a two-story ADU with balcony access through a sliding glass door
The loft lands you off the stair into usable space — office, play area or second living room — with the balcony beyond.

The stair arrives at a loft rather than a hallway — a flexible landing zone that works as a home office, study corner or second living room, and opens through a slider onto the balcony. In two-story layouts, this is the move that separates a well-planned unit from a stack of corridors: circulation space that earns its keep.

05Bedrooms with actual views

Second floor ADU bedroom with three windows framing San Gabriel mountain views in Rosemead CA
Second-floor bedroom, windows on two walls — San Gabriel mountains one way, city lights the other.

This is the argument for building up. On the ground you’d be looking at a block wall; on the second floor these bedrooms get mountain views on one side and city views on the other, light from two directions, and privacy no single-story backyard unit can offer. One bedroom adds a walk-in closet — rare in ADUs at any size.

06The balcony

Private second-floor balcony of a Rosemead two-story ADU overlooking the neighborhood
Private outdoor space that costs no yard: the second-floor balcony.

A backyard ADU normally trades away outdoor space; a second-floor balcony gives some of it back without touching the lot. It’s also the kind of feature that shows up directly in rent: outdoor space and views are what listings lead with.

Why two stories was the right call here

A 1,188 sq ft single-story unit would have consumed most of this backyard. Building up put the same square footage on roughly half the ground footprint — keeping yard, keeping setbacks comfortable, and buying the views and privacy the bedrooms now enjoy. If your lot is tight but your space needs aren’t, this is the trade to study: our two-story ADU guide covers height rules, structural costs and when the math works, and the cost calculator gives a 2026 range for any size at our published rates.

Building in Rosemead or the San Gabriel Valley?

We design and build ADUs across Orange County and Los Angeles County, including the San Gabriel Valley. City rules differ — our ADU rules quick-reference table shows how requirements vary city to city, and the Los Angeles ADU page covers the LA side. If you are in Pasadena, the Pasadena ADU guide covers the SGV city with the most distinctive review process. 我們提供中文服務 — 請參閱中文 ADU 指南。Call (949) 374-7980 for a free site evaluation.

Quick answers

How big can a two-story ADU be in California?
Qualifying lots are entitled to a detached ADU of up to 1,200 sq ft, and state law protects at least 1,000 sq ft for ADUs with more than one bedroom. Height limits vary by city — many allow two stories, which is how this 1,188 sq ft, 3-bedroom unit was possible. Our two-story ADU guide covers the height rules in detail.
Does a 1,188 sq ft ADU need a big lot?
Not necessarily — that is the point of building up. Two stories put this unit on roughly half the ground footprint a single-story would need, so it fits typical suburban lots after the standard 4-foot side and rear setbacks while still keeping usable yard.
Do you build ADUs in Rosemead?
Yes — L Square Design & Build (CSLB #1095476) builds ADUs across Orange County and Los Angeles County, including Rosemead and the San Gabriel Valley. This project is one of ours; a free site evaluation is the first step.
How much does an ADU like this cost to build?
Every lot prices differently, so we don't quote projects by photo. At our published 2026 rates, custom detached ADUs run $270–$380 per sq ft depending on site conditions and finishes — the calculator on our ADU cost guide gives a range for any square footage in seconds.

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