Welcome to your go-to resource on everything related to granny flats! Whether you’re exploring options to house a loved one, add rental income, or simply want more space, this guide covers it all. From floor plans to financing and choosing the right builder, here’s what you need to know to confidently move forward with your project.
What Is a Granny Flat?
Granny Flat Meaning
A granny flat, also known as an accessory dwelling unit (ADU), is a secondary living space on a residential property. It’s commonly used to house family members, especially aging parents or grown children. Homeowners also use these units to generate rental income or as flexible living space. This could include a home office, a gym, or a guest suite.
Where Does the Name Granny Flat Come From?
The name “granny flat” comes from the traditional use of these units to house elderly family members. It’s a popular option for multi-generational living, where two or more generations share the same property. By building an ADU, families can offer loved ones a private and independent space while still remaining nearby. Read more about building a granny flat for multi-generational living.Â
In California, and particularly San Diego, granny flats have seen a rise in popularity since 2020. New state laws made it easier for homeowners to add these units. Statewide, every property is entitled to a detached ADU of up to 800 square feet, a junior ADU of up to 500 square feet within the primary residence, and a conversion ADU. San Diego has gone further by introducing a bonus ADU program.
What Is the Difference Between a Granny Flat and an ADU?
Technically, there is no difference between a granny flat and an ADU. These terms are used interchangeably. To qualify as an ADU, the structure must be at least 150 square feet and include a bathroom and a kitchen or kitchenette.
Different terms like carriage house, casita, or tiny home often reflect regional language or historical use. Before California formalized ADU laws, many homeowners referred to these units simply as granny flats.
The Benefits of Building a Granny Flat
Financial Benefits
Building a granny flat can be a smart financial move. It adds square footage to your property and boosts resale value. Homes with ADUs typically sell at a premium because they offer additional living space and the potential for rental income. With rising demand for multi-generational housing, properties with ADUs are even more appealing to buyers.
Many homeowners also use granny flats to generate passive income by renting them out. This added cash flow can offset mortgage costs or serve as long-term investment income. Learn more about ADU ROI.
Lifestyle Benefits
Granny flats are incredibly versatile. While they’re ideal for multi-generational living, they also work well as guest suites, home offices, gyms, or even pool houses. Because of their flexibility, they adapt to changing lifestyle needs. You might use it for your parents now, but later convert it into an income-producing rental or workspace.
This versatility adds to your home’s appeal during resale. Potential buyers may envision a range of uses, making the property more desirable. Read more on multi-generational living.
Where Can I Build a Granny Flat?
In California, statewide law permits a single-family property to include one detached ADU (up to 800 sq ft), one junior ADU (up to 500 sq ft within the main home), and a conversion ADU. Multifamily properties are allowed even more: at least two detached ADUs plus conversion units.
Each city may offer more generous guidelines. San Diego ADU regulations for instance allow for detached ADUs up to 1,200 square feet and allows two-story units. Through its affordable bonus program, some properties qualify for additional detached ADUs if they are rented to low to moderate income tenants. Some jurisdictions are even more lenient with ADU size. For example, the city of Poway allows ADUs up to 1,500 square feet. See our ADU regulations to see the rules for your city.
Granny Flat Designs and Floor Plans
Granny Flat Floor Plans
When designing a granny flat, it’s crucial to maximize both space and privacy. At SnapADU, we’ve designed over 100 units. You can choose from our past client plans, modify an existing design, or start fresh with something custom. Some cities offer pre-approved ADU plans to speed up permitting and reduce costs. Working with a team that specializes in ADUs ensures your space functions efficiently within limited square footage.
1 Bedroom Floor Plans
One-bedroom granny flats usually range from 400 to 750 square feet. These units include a living room, kitchen, bathroom, and a private bedroom. Layouts vary widely from square and rectangular to L-shaped depending on the lot shape and preferences. Explore one bedroom granny flat plans.
2 Bedroom Floor Plans
Two-bedroom layouts are popular for many reasons. They attract higher rents and can significantly boost resale value. These plans typically range from 600 to 1,200 square feet. Homeowners often choose two-bedroom units for extended family living or to increase income potential.
We’ve designed multiple two-bedroom, three-bedroom, and even four-bedroom ADUs. All are available on our website to view or customize. Explore two bedroom granny flat plans, three bedroom granny flat plans, and four bedroom granny flat plans.
How Much Does a Granny Flat Cost?
Cost to Build a Granny Flat in San Diego
The total cost of building a granny flat depends on size, finishes, site conditions, utility complexity, and access. Most detached ADUs in San Diego cost between $300,000 and $500,000 all-in. However, this can vary. A large unit on a challenging lot might exceed this range, while a smaller ADU using a pre-approved plan and modest finishes may fall below it.
Financing Options for Your Granny Flat
There are several ways to finance a granny flat, including home equity loans, renovation loans, construction loans, and cash-out refinancing. At SnapADU, we partner with trusted lenders who can help guide you through the process.
It’s important to understand your full project scope early on. Site work, utilities, construction, finishes, design, and permitting all affect your budget. Careful planning ensures your project stays on track.
Read more about ADU Financing.
Building a Granny Flat: What to Know Before You Start
Building Process
Building a granny flat involves several stages. First comes a feasibility study and custom design. Then you’ll move into permitting and revisions. After that, construction begins.
The construction phase includes site preparation, trenching and foundation, framing, rough mechanical, electrical, and plumbing, followed by exterior finishes, insulation and drywall, and finally interior finishes. A final inspection completes the process.
Check out our construction process guide.
Feasibility as the First Step
A feasibility study is essential to determine if building a granny flat on your property makes sense. At SnapADU, our feasibility studies include zoning checks, site analysis, utility mapping, and concept floor plans with 3D renderings.
This upfront work helps avoid costly surprises later, like unexpected site constraints or utility issues. With a solid understanding of the scope and cost, you can move forward with confidence.
Learn more about our feasibility studies.
Choosing the Right Granny Flat Builder
Working with Granny Flat Contractors
Partnering with a licensed and experienced team is key. Specialized builders understand local rules, permitting, and design challenges. At SnapADU, we offer an all-in-one service to make the process smoother.
When choosing a granny flat builder, look for specialization in ADUs, a robust project portfolio, local knowledge, transparent pricing, realistic timelines, strong communication, milestone-based payments, warranties, and positive reviews. Avoid red flags like vague quotes, large upfront deposits, and a lack of project history. Check out our guide to choosing your ADU provider.
How to Get Accurate Quotes and Avoid Common Pitfalls
Different ADU providers operate in different ways. SnapADU is a full-service design-build firm that handles everything in-house. Others may be consultants who outsource construction and design.
Make sure quotes include everything: feasibility, design, permit management, site work, vertical build, utility hookups, and finish materials. Look out for hidden costs, mismatched scopes, or unrealistic timelines. A trustworthy contractor will give you a clear and complete picture. You can read more in our guide to comparing ADU quotes.
Top Granny Flat Builders in San Diego: Why SnapADU?
Since 2020, SnapADU has been San Diego’s go-to ADU expert. We’ve completed over 100 granny flats and continue to lead the region in quality and innovation. Our clients value our clear communication, predictable outcomes, and detailed project tracking.
Visit our projects page to see real examples, from feasibility through construction. You’ll also find video testimonials and customer reviews that show what it’s like to work with us.
0 Comments