Backyard Cottage vs ADU: Are They the Same Thing in California?

If you're a Sacramento homeowner standing in your backyard right now, looking at that space and thinking about adding a small, cozy unit for your aging parents or adult kids, you've probably run into the terms "backyard cottage" and "ADU" and wondered if they're different. You may be concerned about rules, costs, or whether your lot meets the qualifications. I've been in conversations like this with families for years and people in their late 30s to mid-60s, already owning a single-family home, planning long-term, with budgets typically between $150,000 and $400,000. The question always boils down to: "Is a backyard cottage just an ADU with a nicer name, or is there a real difference?"

The clear answer in 2026: In California, a backyard cottage is an ADU. The state does not treat them as separate categories. The California Department of Housing and Community Development (HCD) and local jurisdictions like Sacramento County and the City of Sacramento use "Accessory Dwelling Unit" as the legal term, but everyone including the homeowners, builders, real estate agents, and even county planners, they often calls detached backyard units "backyard cottages" because that's exactly what they look like: small, charming, cottage-style homes.

The state has been very intentional about this since the big ADU law changes starting in 2020 and continuing through 2025–2026 updates. The goal is to make it simple to add secondary housing, whether you call it a cottage, granny flat, in-law suite, or backyard dwelling. So, when someone says "I want to build a backyard cottage," they mean an ADU and all the same rules, benefits, and processes apply. Talk to an ADU Expert

Why People Confuse Backyard Cottages and ADUs

The confusion is understandable. "Backyard cottage" sounds warm, traditional, and small-scale, while "ADU" sounds official and bureaucratic. But in reality, they're describing the same thing: a secondary, independent living unit on your property.

Common names used interchangeably in California (all mean ADU):

• Backyard cottage

• Backyard dwelling

• Small backyard home

• Granny flat/in-law unit

• Detached accessory unit

  
  

The state law (Government Code § 65852.2) and the HCD ADU Handbook (updated January 2025) confirm this: any detached secondary dwelling with full facilities (kitchen, bath, sleeping area) is an ADU, no matter the nickname. Start My ADU Plan

I've seen this play out many times. A family in Roseville once told me they wanted a "backyard cottage" for their parents — they were relieved when we explained it was the same as an ADU and qualified under the same streamlined rules. That clarity alone saved them months of worry.

Eligibility: Can You Build a Backyard Cottage / ADU on Your Property?

Most single-family properties in the Sacramento 60-mile radius qualify for a backyard cottage (i.e., detached ADU) under 2026 rules. The state has made eligibility very broad to encourage more housing.

Core eligibility requirements:

• You must have a primary single-family home on the lot (existing or proposed).

• The property is zoned for residential use (most R-1/R-2 zones qualify).

• No strict minimum lot size — state law overrides local restrictions in many cases.

• No owner-occupancy requirement for most new ADUs (rule extended past 2025).

Local Sacramento specifics:

• Sacramento County — Allows ADUs on nearly all single-family lots; 4-foot side/rear setbacks; pre-approved plans available.

• City of Sacramento — Similar rules; height limits 16–25 feet for detached units.

• Primaries (Elk Grove, Roseville, Folsom, Citrus Heights, etc.) — All follow state standards with minor local tweaks.

• Secondaries (Vacaville, Davis, Woodland, Rocklin, Lincoln, Vallejo, Antioch) — Same state overrides apply; confirm your address for any special overlays.

To check your lot quickly, use the Sacramento County Online Map Viewer or the City's ADU Resource Center — enter your address for instant zoning/eligibility feedback.

For more on eligibility, see our post on can I build an ADU on my property — it has step-by-step tools. Talk to an ADU Expert

Zoning & Lot Rules for Backyard Cottages / ADUs

Zoning is where confusion often peaks, but the rules are clear and homeowner-friendly in 2026. Standard Sacramento-area requirements:

• Setbacks — 4 feet minimum for side and rear yards (conversions usually exempt).

• Height — 16 feet for most detached backyard cottages; up to 25 feet if attached.

• Lot Coverage — Varies by zone, but state law allows reasonable coverage.

• Parking — No additional parking required for the ADU in many transit-accessible areas.

Pre-approved plans (required by cities since 2025) make compliance much easier — you pick from approved designs and skip long custom reviews.

Costs & Timeline: What to Expect for a Backyard Cottage / ADU

Costs for a backyard cottage (detached ADU) typically range from $250,000 to $400,000 in Sacramento, depending on size and finishes. Garage conversions are cheaper ($150k–$250k) if you have an existing garage.

For a realistic budget breakdown, check our detailed post on how much to build an ADU.

For the full process from eligibility to completion, see our step-by-step guide on Talk to an ADU Expert

If you're exploring designs that fit your lot and budget, browse our ADU models, any aof which re cottage-style detached units that families love.

Ready to Explore a Backyard Cottage / ADU for Your Family?

A backyard cottage and an ADU are the same thing under California law — and the rules are designed to make it easier than ever to add that extra space for family or income.

If your property qualifies and you're ready to discuss options with no pressure, give us a Call us at +1 (916) 238-8240 we'll give you clear, realistic answers tailored to your situation.

Frequently Asked Questions

1. Is a backyard cottage the same as an ADU in California?

Yes "backyard cottage" is a common name for a detached Accessory Dwelling Unit (ADU). California law uses "ADU" officially, but all the rules are the same. Get ADU Cost Estimate

2. Can I build a backyard cottage on my single-family lot in Sacramento?

Most single-family lots qualify in 2026, with 4-foot setbacks, 16–25 foot height limits, and no owner-occupancy requirement for most new units.

3. What is the cost range for a backyard cottage / ADU?

Typical range is $250,000–$400,000 for detached units; garage conversions are lower ($150k–$250k). See our full cost guide for details. Talk to an ADU Expert

4. Are there size limits for backyard cottages in California?

Detached ADUs (backyard cottages) can be up to 1,200 sq ft in many zones; smaller cottage-style units inside the home are JADUs (max 500 sq ft).

5. How do I check if my property is eligible for a backyard cottage / ADU?

Use the Sacramento County Map Viewer or City ADU Resource Center — enter your address for instant zoning and eligibility info. Get ADU Cost Estimate