A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Monrovia, CA
Monrovia isn’t like building in Arcadia or Pasadena. The hillside lots, the narrow railroad-era parcels, the Craftsman homes from the early 1900s – every ADU project here asks different questions than a flat, gridded lot would. We’re Seedling ADU Builders, and we work on accessory dwelling units, garage conversions, and home additions across Monrovia with written pricing before any tool gets picked up. Call us at (626) 657-5461 for a free estimate on your project.
Why Monrovia Homes Are Different
Monrovia grew along the 1887 land boom and the 1903 Monrovia-Rancho Duarte Short Line railroad, which left behind long, narrow lots – many 50 feet wide by 150 feet deep – and homes that were platted before cars changed how people thought about garages and setbacks. Many of the city’s early 20th-century Craftsman bungalows and mid-century ranch homes sit on lots that slope toward the San Gabriel Mountains, which means foundation work, drainage, and utility runs all need to be planned differently than they would be on a flat lot in neighboring Arcadia.
The mountains also bring wind. Santa Ana winds move through Monrovia’s foothill neighborhoods, and hillside ADUs face real exposure during winter rain events. That’s why we recommend wildfire-resistant siding, wind-rated framing, and erosion control on hillside jobs – not because it’s a nice add-on, but because Monrovia’s geography asks for it.
Older homes on those deep lots often have aging foundations. When we plan an ADU or garage conversion on a 1910s or 1920s home, we check what’s underneath first. Sometimes the foundation needs reinforcement before any new structure ties in, and that’s a normal part of the work here – written into the price before we start, not discovered later as a surprise change order.
Our Main Monrovia Services
The three projects Monrovia homeowners call us about most are home additions, garage conversions, and new ADUs. Each one has its own page with Monrovia-specific detail, pricing, and what to expect.
Home Addition Contractor in Monrovia
Adding a bedroom or a family room to a 1920s Craftsman on a narrow lot takes careful planning around existing footings, rooflines, and the slope of the property. Our Home Addition Contractor in Monrovia page walks through how we handle foundation reinforcement, matching roof pitches, and keeping the existing house livable while the addition goes up. Every addition gets a written price before work begins, and the crew follows the Cedarwell Care Promise: shoe covers, drop cloths, and a photo of the clean-up before we leave each day.
Garage Conversion Contractor in Monrovia
Monrovia has more detached garages from the Model T era than almost any neighboring community – narrow, shallow structures that were built for cars smaller than a modern Civic. Converting one into a livable space means working within tight dimensions, often adding insulation and new electrical from scratch, and sometimes reframing to meet current minimum room sizes. Visit our Garage Conversion Contractor in Monrovia page for the full breakdown. On Myrtle Avenue and the surrounding blocks, we’ve converted garages that still had their original alley-facing doors intact.
ADU Builders in Monrovia
A new ADU in Monrovia is a new home on your lot – separate entrance, separate utilities, built to last. Hillside lots here often require pier-and-beam foundations or retaining walls before the unit goes up, and the city’s setback rules on narrow lots can influence placement more than they would in the flat valley. Our ADU Builders in Monrovia page covers design options, prefab versus stick-built choices, and what to expect from permits to final inspection.
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.
Brands We Service in Monrovia
We work hands-on with the brands serious ADU buyers research before calling anyone: our brands include Abodu, Cover, Dvele, and James Hardie materials. Homeowners can compare what each product offers for their specific lot – hillside or flat, narrow or wide – rather than settling for whatever the builder prefers to sell.
Pricing for ADU Company in Monrovia, CA
| Service | Typical range in Monrovia |
|---|---|
| New detached ADU (permits, foundation, utility hookups) | $180,000 – $320,000 |
| Prefab ADU (Abodu, Cover, or Dvele unit, site prep, utilities) | $120,000 – $260,000 |
| Garage conversion to ADU (full livable unit) | $110,000 – $190,000 |
| Garage conversion to studio or office (no kitchen) | $70,000 – $120,000 |
| Detached home addition (one bedroom, one bath) | $140,000 – $240,000 |
| Second-story addition | $220,000 – $380,000 |
| Foundation reinforcement on pre-1920 home | $8,000 – $25,000 |
| Hillside retaining wall (up to 4-foot height) | $6,000 – $18,000 |
| Utility trenching and connections on hillside lot | $4,000 – $12,000 |
| James Hardie siding package for ADU | $12,000 – $28,000 |
Monrovia prices shift most on hillside lots – foundation work, retaining walls, and longer utility trenches add real cost. On flat lots near the Myrtle Avenue corridor, the same ADU often lands at the bottom of the range. Whatever the number, you’ll see it in writing before we start, and it won’t change once crews arrive.
Neighborhoods We Serve in Monrovia
We work in every part of Monrovia, from the foothill streets north of Foothill Boulevard to the flatland blocks south of Huntington Drive. Response times vary by crew availability, but most estimates happen within a few days of your call.
- North Monrovia (foothill slopes)
- Historic Myrtle Avenue corridor
- Monrovia Old Town area
- Mayflower Village side streets
- Canyon Park neighborhoods
Service Area – Cities Near Monrovia
Along with Monrovia, we take ADU, garage conversion, and home addition projects in the surrounding foothill and valley communities. If you’re in Sierra Madre, CA, Baldwin Park, CA, San Marino, CA, or Rosemead, CA, we can schedule an estimate and put together the same written pricing.
Serving Monrovia, CA - Our Local Coverage Area
We’re based in the Monrovia 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 About ADU Company in Monrovia
Yes. City of Monrovia permits are part of the scope on every ADU, garage conversion, and home addition we build. We handle submittal, corrections, and inspections from start to finish. Call (626) 657-5461 and we’ll walk you through the Monrovia permit timeline for your specific lot.
Hillside lots typically need retaining walls, deeper foundations, or pier-and-beam work, which adds both cost and time compared to a flat Monrovia parcel. The price difference is written into your estimate before work starts, so it’s not a surprise later. Call (626) 657-5461 for a free site assessment on your slope.
No. Seedling gives you a written price before any work begins, and that number holds unless you choose to change the scope mid-project. If we find an issue during the build – an aging foundation, an unexpected utility line – we discuss it before touching anything, and any new cost is agreed on in writing. Your estimate is free; call (626) 657-5461 to schedule one.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Monrovia Customers Say
"Built a backyard unit for us. For a months long project the crew kept the site remarkably tidy, swept daily, and were respectful of our neighbors and our dog. Beautiful result."
- Charlotte Vey"Backyard cottage build. For a long project they kept the site remarkably tidy and were respectful of our neighbors and our dog. Swept the driveway every evening."
- Leona Pfeiffer"Garage conversion into a studio. They sealed off the work area so dust didn't get into the house, and cleaned up every day before leaving. Calm, careful team to have around."
- Darnell Hobbs
