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ADU & Room Addition Experts in California
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Stunning Additions That Feel Like They Were Always There
From backyard guest houses to seamlessly integrated master suites, explore how we’ve helped California homeowners unlock the full potential of their properties.
ADU & Room Addition Services
Your home should grow with your family — and your goals. Whether you’re looking to add rental income, house a loved one, create a dedicated home office, or simply gain more living space, Greenline Home Remodeling makes it happen. We specialize in building accessory dwelling units (ADUs) and custom room additions that are thoughtfully designed, expertly built, and fully permitted — so you can enjoy your new space with total peace of mind.
We handle every permit, inspection, and city approval — navigating California's ADU regulations so you don't have to.
Our designers work around your lot, your lifestyle, and your budget to create a space that feels like a natural extension of your home.
From foundation to finishing touches, we use premium materials and skilled craftsmanship for builds that last for decades.
We respect your time and your home. Our project managers keep timelines tight and communication clear from day one to move-in day.
Book an Appointment
Book an Appointment With Our ADU & Addition Specialists
Marketing Director
"Greenline built a beautiful ADU in our backyard for my mother-in-law. From permits to painting, they handled everything professionally. The unit looks like it's always been part of our property."
Creative Lead
"We added a 400 sq ft home office and it completely changed how we work and live. The team was respectful of our space, stayed on schedule, and the quality is outstanding."
IT Manager
"From the design consultation to the final walkthrough, Greenline made the entire process easy. Our room addition came out better than we imagined — and it added serious value to our home."
Common Questions
Frequently Asked Questions
What is an ADU and do I qualify to build one on my property?
An Accessory Dwelling Unit (ADU) is a self-contained living space built on the same lot as your primary home — such as a detached backyard unit, a garage conversion, or an attached suite. California state law has significantly expanded ADU eligibility, and most single-family and multifamily properties qualify. We offer free consultations to assess your property and walk you through exactly what’s possible.
How much does an ADU or room addition cost in California?
Costs vary based on size, type, and site conditions. Garage conversions typically start around $80K–$120K, detached ADUs range from $150K–$300K+, and room additions generally run $50K–$150K depending on scope. We provide detailed, transparent estimates after an on-site consultation so there are no surprises.
How long does it take to build an ADU or room addition?
Most room additions take 2–4 months from permit approval to completion. A detached ADU typically takes 4–8 months depending on complexity and city processing times. We’ll give you a realistic project timeline upfront and keep you updated throughout every phase.
Will you handle permits and approvals with the city?
Absolutely. Permitting is one of the most complex parts of any ADU project, and we manage it entirely on your behalf. Our team is experienced with building departments across LA County and the Bay Area, and we ensure your project meets all local and state requirements.
Can an ADU be used as a rental unit?
Yes — and many of our clients build ADUs specifically for rental income. A well-designed ADU in California can generate $1,500–$3,500+ per month in rent, making it one of the highest-return home improvements available.
Do you handle garage conversions and attached ADUs as well?
Yes. We build all ADU types — detached units, attached additions, garage conversions, and junior ADUs (JADUs). During your consultation, we’ll help you determine which option best fits your goals, your property, and your budget.
Will an ADU or room addition increase my home's value?
Significantly. Adding livable square footage — especially a permitted, self-contained unit — is one of the most effective ways to increase property value in California. Our clients consistently see strong returns at resale and benefit from added rental income in the meantime.
How do I get started with Greenline?
We provide a free on-site consultation and detailed estimate. Once approved, our designers create plans tailored to your property and goals, we handle permits, and our team builds your new space to the highest standards.