ADUs & Additions in Hacienda Heights

Los Angeles County Public Works, Building and Safety Division (La Puente District Office). Hacienda Heights is unincorporated, so building permits come from Los Angeles County Public Works, Building and Safety, through its La Puente District Office, and when Fire Department plan approval is required, building plans for the community go to the Diamond Bar Fire Prevention office. The office's agency referral sheet flags hillside development on slopes of 25 percent or more for drainage plan check covering stormwater (NPDES and Low Impact Development) compliance, and where grading plan check applies, rough-grade approval is required before the building permit issues. Zoning falls under the East San Gabriel Valley Planning Area Standards District (Title 22, Chapter 22.366), effective June 20, 2024, which keeps the highest point of a structure at least 50 vertical feet and 50 horizontal feet from a designated Significant Ridgeline, bars any part of a structure from blocking the view of one from a designated Scenic Route, and requires a Variance where a lot cannot meet those standards. We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.

Mostly single-family homes from the post-war suburban boom, many set on inward-facing, non-connecting streets and cul-de-sacs. Toward the south and on the western slopes, the ground rises past 25 percent slope into the Puente Hills, where ridgeline, fire and hillside rules begin to shape what fits on a lot. One local condition that shapes the work: County planning for the East San Gabriel Valley Area Plan places many portions of Hacienda Heights within Very High Fire Hazard Severity Zones and Hillside Management Areas, along some 25 miles of wildland-urban interface around the Puente Hills.

All of it, including Turnbull Canyon, Camino del Sur and Kwis Avenue. Our crews run every job out of our Cahuenga Pass base in Los Angeles, with our own people on site.

Detached ADU: generally $150,000 to $400,000+ across Southern California. What moves it is square footage, finish level, utility runs, and site access; garage conversions typically run well below a ground-up detached build. We give line-item pricing after seeing the site rather than quoting a number over the phone.

Plan a realistic year. Design and engineering typically take one to three months, city plan check and corrections add several more, and construction usually runs four to eight months depending on size and site access.

Usually yes, and often substantially, because the foundation, walls and roof already exist. The trade-offs are that you lose the garage, and older slabs and framing sometimes need upgrading to meet current code.

California ADU law is designed to allow long-term rental, and an ADU is one of the few ways to add rentable square footage to a single-family lot. Short-term rental rules vary by city, so confirm your local ordinance before counting on that income.

Yes. Plans, engineering, Title 24 and the city submittal are all handled in-house, including responding to plan-check corrections. That is a service we sell on its own, so it is not something we hand off.