Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Before
After
Before
After
Before
AfterFast, Reliable Home Additions & ADU Across Hacienda Heights
Adding square footage or building an ADU in Hacienda Heights runs $45,000-$130,000 for a room addition and $90,000-$220,000 for a new detached ADU, and the permit path is different here than almost anywhere else in the San Gabriel Valley. Hacienda Heights is unincorporated LA County, which means every addition and ADU gets reviewed under LA County’s Title 26 Building Code, not a city building department. Our crews work these hillside parcels off Colima Road, Hacienda Boulevard, and Gale Avenue every week, and we know what county plan-checkers look for before a single wall comes down. Call (877) 610-1318 and we’ll walk your lot before you spend a dollar on plans.
Why Barrett & Sons Construction Is Hacienda Heights’s Preferred Home Additions & ADU Company
Tom Barrett started this company in 1998, and his sons run crews across Hacienda Heights today. That matters when a county inspector raises a grading question on a hillside lot and someone has to make a call on the spot. We’re not dispatching strangers; the person who walks your job is the person whose name is on the truck.
Hacienda Heights homeowners call us because we understand the unincorporated permit path. We’ve pulled LA County permits for room additions off Kwis Avenue, second-story additions near Los Altos Drive, and garage conversions in the neighborhoods around Wedgeworth Elementary. County plan-check is stricter here than in La Puente or Whittier, and we plan for it from day one.
Every Barrett & Sons job includes permits pulled and inspections signed. Every price change comes as a written change order before work proceeds, and every completed job carries the 90-Day Done Right Promise. Tom publishes his name, address, and license number. Look it up before you sign anything. A live person answers our phone 24/7, not a voicemail box.
Our Home Additions & ADU Services in Hacienda Heights
ADU Design & Permitting
An ADU in Hacienda Heights starts with a soils report and a grading plan, because most lots here sit on cut-and-fill terrain with expansive clay. We handle LA County submittals, Appendix J hillside grading review, and all the back-and-forth with plan-check. You’re not chasing paper; we are. A detached ADU in Hacienda Heights typically runs $90,000-$220,000, and the engineered foundation work is a big reason that range sits higher than flat-lot cities.
Room Additions
Adding a bedroom, family room, or extended kitchen to a 1960s ranch in Hacienda Heights means opening walls and finding what’s behind them. Original wiring, undersized headers, notched studs. We inspect first, write allowances into the contract, and any hidden condition gets priced and approved in writing before we touch it. Room additions here run $45,000-$130,000, and soil engineering on a sloped lot is often what moves that number toward the top of the range.
Second Story Additions
A second story on a Hacienda Heights hillside home triggers county structural review of the existing foundation. Many of these 1960s-1980s homes were built with cut-and-fill grading, and county plan-checkers will require a foundation assessment before approving vertical load changes. We bring in a soils engineer, confirm what the existing footings can carry, and design the addition around the science. If the foundation needs reinforcement, you’ll see it on paper before we pour anything.
Garage Conversion ADU
Converting a garage in Hacienda Heights runs $30,000-$80,000, and the permit path is a county review, not a city one. LA County plan-check will look at the slab, the walls, and whether the original garage was built to residential standard. Many weren’t. We handle the structural upgrades, the new electrical service, and the insulation and drywall to make it a legal dwelling unit, not a garage with a bed in it.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Hacienda Heights
We install windows and doors you can look up, not mystery brands off a van. On Hacienda Heights additions and ADUs, we regularly install Simonton windows, Ply Gem siding and trim, and PGT impact-rated glass where hillside exposure calls for it. Our Home Additions & ADU team stocks common sizes and finishes locally, which keeps a window swap from turning into a two-week wait. If a brand matters to you, tell us before we order; we’ll price it into the written quote.
Common Home Additions & ADU Problems We See in Hacienda Heights Homes
- County plan-check rejection for missing soil engineering. A contractor used to pulling city permits in La Puente or West Puente Valley submits a hillside addition without a soils report, and LA County bounces it back. The job stalls for weeks. We pull the soils report before we submit the first plan set.
- Expansive clay shrink-swell cracks slabs and heaves retaining walls. Hacienda Heights clay soils move with moisture, and decades of wet-dry cycles have left original concrete block walls leaning and slabs cracked. A new addition or ADU has to account for that movement, or the new work inherits the old problems.
- Opening a wall and finding undersized beams or notched load-bearing studs. Homes built during the 1960s-1980s boom often have framing that doesn’t pass today’s structural review. County plan-check flags it, and the reframe becomes a change order. That’s why we write inspection allowances into every contract.
- Failed waterproofing on sloped parcels after the first wet-season rain. Hacienda Heights gets more pronounced wet-season rain than coastal LA, and water runs downhill. If the new addition’s drainage detail wasn’t engineered for the slope, you’ll find out the first winter. We do a pre-construction drainage study on any sloped lot before we break ground.
Pricing for Home Additions & ADU in Hacienda Heights, CA
Here’s what Hacienda Heights homeowners can expect to pay for our most requested projects:
| Project | Typical Hacienda Heights Range |
|---|---|
| Room Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Garage Conversion | $30,000-$80,000 |
Those ranges reflect what we actually see on Hacienda Heights lots: soils reports, grading permits, retaining wall work, and engineered foundations on sloped parcels. Hillside work costs more than flat-lot work; that’s not a markup, it’s engineering. We don’t quote one number on the phone and hand you a different bill at the door. Every scope and every allowance is in writing before work starts, and every change order crosses your desk before a nail moves. Call (877) 610-1318 for a free estimate on your specific lot.
We Also Serve Cities Near Hacienda Heights
Our crews work the whole eastern San Gabriel Valley. In addition to Hacienda Heights, we serve La Puente, Valinda, Avocado Heights, and West Puente Valley. Different permit offices, same standard: permits pulled, inspections signed, and written change orders on every scope change. If you’re in a neighboring city, the same Tom Barrett does the work.
Serving Hacienda Heights, CA - Our Local Coverage Area
We’re based in the Hacienda Heights area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Home Additions & ADU in Hacienda Heights
Most likely yes, if your lot is on sloped or cut-and-fill terrain. LA County plan-check will evaluate the existing grading and typically requires a soils report and a grading plan before approving vertical construction. We handle the full submittal, including Appendix J hillside review. Call (877) 610-1318 and we’ll tell you what your specific parcel triggers before you spend money on plans.
We inspect first, then write allowances into the contract so you know what a hidden condition will cost before we open the wall. If we find something like cloth-insulated wiring or notched load-bearing studs, we bring it to you with a written change order and a fixed price. You approve it in writing before we proceed. That’s how it works on every Barrett & Sons job.
Because Hacienda Heights is unincorporated LA County, so every permit goes through LA County Building and Safety under Title 26, and the county enforces hillside grading ordinances far more rigorously than incorporated cities. La Puente and Whittier have their own building departments with different codes and faster turnaround for flat-lot work. We account for county review time in every Hacienda Heights schedule.
You’ll need a soils report before design, and the foundation design will likely require deeper footings, engineered slab reinforcement, or helical piers depending on what the soils report shows. The expansive clay shrink-swell cycle is a real issue across Hacienda Heights, and county plan-check will not approve a foundation that doesn’t account for it. We bring in the geotechnical engineer as step one.
Yes. A junior ADU or garage conversion in unincorporated Hacienda Heights requires LA County permits, including structural review of the existing slab and walls, electrical service upgrades, and insulation and ventilation to residential code. Skipping the permit works until you sell the house or the county finds out. We pull the permit, pass the inspection, and hand you the signed paperwork. Call (877) 610-1318 for a free estimate and we’ll walk your garage with you.
If you’re considering a home addition or ADU in Hacienda Heights, call (877) 610-1318 to schedule a free estimate. Tom Barrett or one of his sons will walk your lot, talk through what your parcel actually needs, and put every number in writing before you commit to anything.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Hacienda Heights and the eastern San Gabriel Valley since 1998.