Accessory Dwelling Units (ADUs), commonly known as guest houses, granny flats, or casitas, are one of the most valuable and in-demand home features in today’s Conejo Valley real estate market. Whether you’re in Westlake Village, Thousand Oaks, Agoura Hills, or Calabasas, ADUs are transforming how homeowners live, invest, and sell.
If you’re considering adding an ADU, or looking to purchase a home that already has one, this guide breaks down everything you need to know from benefits to values to local nuances between cities and counties.
Are you having a hard time finding a home with the right floor plan? Or maybe you already own a home but could use extra income or space for aging loved ones? Either way, accessory dwelling units (ADUs) could be the smart solution you’ve been looking for in today’s market.
What Is an ADU?
An Accessory Dwelling Unit (ADU) is a small secondary housing unit on a single-family or multifamily property, and can be a:
Detached guest house
Attached unit (converted garage, or addition)
Above-garage apartment
Junior ADU (JADU) within the main home
ADUs typically include a kitchen, bathroom, living and/ or sleeping space, and separate entrance, making them fully independent living spaces.
Why ADUs Are So Popular in Conejo Valley
Conejo Valley is known for more elbow room and bigger lots than the average in Los Angeles, which makes the area prime for ADU guest houses. In high-demand areas like Westlake Village, Newbury Park and Calabasas, ADUs offer flexibility and long-term value that homeowners and buyers are actively seeking for 4 main reasons:
1. Rental Income Potential
With rising costs all around, an ADU can help supplement your income or help pay your mortgage, whether through long-term tenants or shorter-term rentals like AirBnB. As of early 2026, California state law requires a minimum rental of 30 days (temporary rental permits are not eligible for ADUs). Please check your local government websites and offices for the most up to date and accurate information. https://rma.venturacounty.gov/
2. Multigenerational Living
Over 50% of homes with ADUs are purchased to accommodate adult children or aging parents/ seniors. ADUs are perfect for:
Aging parents
Adult children
Live-in caregivers
Living close, but still separate. For adult children and extended family, this gives you the best of both worlds like more quality time together yet privacy when you want it.
ADUs are also perfect for aging in place and allows older people to be close to caregivers or loved ones who can help them if they need it. It’s a sweet spot that offers both independence and support.
Lastly, if your extended family is living in the ADU they may be able to support childcare which can also be a cost savings.
3. Increased Property Value
Homes with ADUs often sell for a premium, especially in markets like Thousand Oaks and Agoura Hills where inventory is limited. Keep in mind that your property taxes will also increase based on the value of the ADU. County Assessor
4. Work-from-Home & Lifestyle Flexibility
ADUs make great:
Private home offices
Guest suites
Gyms and Wellness Space
Creative studios (from podcasts to painting)
We’re also seeing ADU trends in 2026 like an increase in prefab and modular options with sustainable and energy-efficient features.
What Buyers Should Know About Homes with ADUs
If you’re searching for a home with a guest house in Conejo Valley, here are a few things to keep an eye out for (things a local real estate expert like Lydia Gable can help with):
Permits & Legality: Was the ADU built with permits?
Separate Utilities: Electric, water, and gas meters
Privacy & Layout: Ideal placement for rental or guests, depending on your needs
Rental History: Proven income potential can be a plus
Zoning Compliance: Ensures future flexibility
👉 Contact the Lydia Gable Realty Group to help you find the perfect ADU property, including off-market opportunities throughout Conejo Valley, and navigate the process. For a quick search, check the end of this blog post for a detailed list of homes with ADUs for sale in Conejo Valley and surrounding areas.
What Homeowners Should Know Before Building an ADU
Adding an ADU is a major investment, but when done right it can significantly increase your home’s usability and value.
Key Considerations:
Lot size and setbacks
Parking requirements (often waived near transit)
Utility connections
Construction costs (typically $200K–$400K+ depending on size and finish)
HOA restrictions (common in parts of Westlake Village, Agoura Hills, Calabasas etc)
Property tax increases based on your ADU value
👉 Want to explore adding an ADU to your property but not sure where to start? Call, text, or email the Lydia Gable Realty Group to help guide you through feasibility, value impact, resources, and next steps.
In today’s market, ADUs are not always a “nice-to-have” but often a deciding factor for buyers. When it comes to Resale Value we’re seeing:
Faster sales for homes with turnkey ADUs
Strong interest from investors and multigenerational buyers
Premium pricing in neighborhoods across Thousand Oaks, Agoura Hills and beyond
However, value depends heavily on:
Quality of construction (we’re seeing increased demand for ADUs with high-end finishes)
Privacy and usability
Permitted vs. non-permitted status
Ventura County vs. Los Angeles County ADU Rules
Understanding the difference between regulations is critical when building or buying. Check local government websites for ADU information, like: https://toaks.gov/index.php?section=adu or https://rma.venturacounty.gov/
Ventura County
Generally more streamlined permitting
Lower fees compared to LA County
Owner-occupancy requirements have been relaxed under state law
Easier approval timelines in many cases
Los Angeles County (Calabasas, Agoura Hills)
Slightly more complex zoning overlays
More design and planning review (especially in hillside areas)
Additional regulations for short-term rentals
Potentially higher permit and utility connection costs
Important: Please always reference state and local regulations for the most accurate info. California state laws have made ADUs somewhat easier to build statewide, but local jurisdictions still influence timelines, fees, and design standards.
Final Thoughts: Is an ADU Right for You?
Whether you’re a homeowner looking to maximize your property’s potential or a buyer searching for flexibility and income opportunities, ADUs are one of the smartest real estate moves in Conejo Valley.
👉 Thinking about buying or selling a home with an ADU or adding one to your property? The Lydia Gable Realty Group is your trusted local expert across Westlake Village, Thousand Oaks, Moorpark, Agoura Hills, and Calabasas. Reach out today to start the conversation.
FAQ Frequently Asked Questions
Do ADUs add value to a home in Conejo Valley?
Yes, homes with permitted ADUs often sell for more and attract a wider pool of buyers, especially in Westlake Village and Calabasas. Keep in mind that your property taxes will also increase based on the value of the ADU. Refer to the County Assessor’s website for more information. The “value” of rental income can also be considered.
How much does it cost to build an ADU?
Costs typically range from $150,000 to $400,000+ depending on size, design, custom or prefab, and location.
Can I rent out my ADU?
In most cases, yes for long-term rentals. Short-term rental rules vary, especially in Los Angeles County cities like Calabasas. Current CA state law dictates 30-day minimums. Check with your city.
Do I need permits for an ADU?
Permitted ADUs are critical for resale value and legal rental use.
Can I convert my garage into an ADU?
Garage conversions are one of the most common and cost-effective ADU types.
Are ADUs allowed in HOA communities?
It depends on the HOA. Some allow them, others restrict or prohibit, so this is especially important to check in planned communities.
What’s the difference between an ADU and a guest house?
The terms are often used interchangeably, but technically an ADU is a fully independent living unit with a kitchen.
How long does it take to build an ADU?
Typically 6–12 months including design, permitting, and construction (often shorter for prefab).
