ADU Contractor · Monrovia, CA
ADU Contractors in Monrovia, California
A plain guide to what an accessory dwelling unit costs, how long it takes, and where budgets go wrong in the San Gabriel Valley foothills.
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ADU Contractor in Monrovia
Pricing & What to Expect
Transparent pricing with no surprise change orders. Every quote is locked for 30 days.
Service LevelCost Range
Garage conversion ADUfrom about $80,000
Detached studio or one-bedroomroughly $150,000 to $300,000
Detached two-bedroomroughly $250,000 to $450,000
Design, engineering and Title 24roughly $6,000 to $20,000
Electrical service upgraderoughly $4,000 to $12,000
Sewer lateral workroughly $3,000 to $15,000
Slope, retaining and drainage workhighly variable
FAQ
ADU Contractor in Monrovia — Questions Answered
How big can an ADU in Monrovia be? +
California law sets floors that a city cannot go below, and cities set their own standards inside those limits, tied to lot size and to whether the unit is attached, detached or a junior ADU. Because the number depends on your specific parcel and unit type, get it from Monrovia's planning counter or its adopted ADU standards for your address rather than from a general figure. Ask at the same time about height limits and setbacks, because those often constrain a design more than square footage does.
Do I need to add a parking space for the ADU? +
Often not. State law removed the ability to require replacement or additional parking for ADUs in several defined situations, including proximity to public transit and certain conversions. It is not a blanket exemption, though, so confirm how it applies to your parcel before you assume you can build over the driveway.
Will an ADU raise my property taxes? +
Building an ADU normally triggers a reassessment of the new construction only, not a reassessment of your whole property. In practice that means the added value of the unit is assessed and added to your existing base. The Los Angeles County Assessor is the authority on how this is applied to your parcel, and a tax professional is the right person to ask about your specific position. Treat any contractor's tax estimate as a guess.
Can I build an ADU myself as an owner-builder? +
Legally you can pull an owner-builder permit in California. Understand what you take on: responsibility for code compliance, for scheduling and passing inspections, and potentially for the legal obligations of an employer toward anyone working on the site. It also affects how the work is treated if you sell. It can make sense for a small conversion where you have real construction experience. For a detached new build it is a large commitment that many homeowners regret partway through.
How do I compare two ADU bids that are far apart on price? +
Put them side by side line by line rather than comparing the totals. Check whether both include design and engineering, permit and plan check fees, utility connections and any service upgrade, site work and drainage, and finish allowances at the same level. Then check what each one excludes in writing. Most large gaps close substantially once both bids describe the same job, and the remaining difference is the one worth discussing.
What should I check about a contractor before hiring? +
Verify the licence number and status directly with the California Contractors State License Board, ask for a current certificate of liability insurance and workers' compensation coverage sent from the insurer rather than as a photocopy, and confirm the payment schedule complies with California's limits on down payments for home improvement contracts. Ask for references on ADU projects specifically, since ADU permitting is its own skill, and speak to a homeowner whose project finished at least a year ago so you hear how the work held up.