How to Choose the Right Granny Flat Plan for Your Home

By 2034, experts predict that seniors will outnumber children in the US. This means that a little over a decade from now, there will be 77 million Americans over the age of 65.

At the same time, housing prices continue to soar, especially in sought-after locales like San Jose. Each year it becomes more challenging to make ends meet. This is especially true for seniors on fixed incomes and recent college graduates starting their careers.

What can families do to ensure that their needs (and the needs of their loved ones) will be met in the years to come? The time to start planning for the future is now. And there’s no better solution for your family’s needs than adding a granny flat to your property.

Don’t be fooled into thinking that “granny flats” are small, cramped, and only for the elderly. Today’s granny flat plans include gorgeous modern designs with spacious layouts and the latest technologies.

Are you thinking of designing a granny flat for your loved ones? What are the latest and greatest granny flat ideas? In this post, we’ll help you design the ultimate granny flat plan for your family’s needs.

Read on for all the inspiration you need!

What Is a Granny Flat Anyway?

First of all, let’s clear up some misconceptions about granny flats.

Despite the name, granny flats aren’t just for elderly family members. They’re perfect for recent graduates or young couples who are starting careers or saving to buy a home. They’re also ideal for family members who have disabilities or other long-term care requirements.

The technical term for a granny flat is an accessory dwelling unit (ADU). You might also hear them called mother-in-law suites, backyard cottages, or accessory apartments.

A granny flat can be a standalone structure in the backyard, or it can be built as an addition to your home. Some families even convert attics, basements, or garages into granny flats–though these types of conversions are more rare in California. It really depends on the amount of space you have to work with and the zoning requirements in your area.

A granny flat plan could be a studio design, or it could feature one or two bedrooms. As a self-contained home, it also has a fully functional kitchen and bathroom. Granny flats are larger and permanent as opposed to smaller mobile or “tiny homes.”On average, granny flats are 300 to 800 sf, but in some instances may go as large as 1,000-1,200 square feet.

Designing a granny flat for your property is a wonderful way to keep the family together while still allowing for independence. You can keep an eye on aging loved ones or family members with special needs. If you have kids, they’re also sure to benefit from spending more time with their grandparents.

Different Types of Granny Flats

Now that we’re clear on what granny flats are, let’s consider the three basic types. Before you start drafting a granny flat plan, you first need to determine which type of structure makes the most sense for your home (and which is legal).

1. Detached Structure or Detached ADU

If you have enough space on your property, a detached ADU is ideal. It stands completely separate from the main house, with no corridors or other connections between the two. With a kitchen, bathroom, living area, and sleeping space, it functions as a complete home.

Think of a small cottage, cabin, or carriage house. It’s larger than a tiny home but smaller than a standard single-family home. It’s also a permanent structure built on a foundation, so an RV or mobile home doesn’t count.

Detached granny flats can be designed in a wide variety of sizes and styles to suit your family’s needs and property limitations. Many granny flat plans feature a porch or patio so your loved one can relax in the fresh air.

2. Attached Structure or Attached ADU

What if your property isn’t large enough to accommodate a standalone structure? Your next best option is to create an external apartment somewhere in your existing home (or garage).

The concept of a fully functional, self-contained home remains the same. The floor plan will still include a kitchen, bathroom, and sleeping area. Most areas require this unit to share at least one wall with the main house.

An advantage to external apartments is that they include a separate entrance from the main home. For some families, this extra level of privacy is desirable. A potential drawback, though, is that they can be tricky to build due to local zoning requirements and restrictions.

3. Internal Structure or Junior ADU

If you’re limited by backyard space utilize a portion of your home to convert into its own secondary home might be an option. However, any time a project touches the primary residence there are structural, architectural, energy, and additional legal considerations.

Though not the most common, conversion options include attics, basements, and garages. Depending on the layout of your home, you might also be able to convert a master bedroom suite into a granny flat. Without a separate entrance, though, you will be sharing some common areas within the home.

This might be the best option for you if your family member has limited mobility, memory loss, or other serious physical conditions. They can retain most of their independence, but you’re close enough to keep an eye on them.

Granny Flat Plans: Legal Considerations

Before you get your heart set on the perfect granny flat plan for your loved one, it’s time for a quick reality check. The size and type of ADU you’ll be able to build depends entirely on what’s allowed in your area, on your property, the conditions of your property, and your budget..

In San Jose, for example, what can you build on a single-family lot of up to 9,000 square feet? Your options include a detached granny flat up to 1,000 square feet or an attached ADU up to 800 square feet. However, other outliers like trees, easements, plumbing and utility connects, slopes,, not to mention budget will make an impact the final size.

If your lot is larger than 9,000 square feet, you can design a detached granny flat plan of up to 1,200 square feet, at which point you can expect to budget for building a single family house! As for attached ADUs, they may be up to 50% of your home’s total size (for example, 1,100 square feet on a 2,200 square foot house). This effectively splits the home in two, and creates additional requirements like energy efficiency, fire protection, structural engineering, etc.

Meanwhile, if you live on a duplex or multifamily lot (regardless of the size), the largest ADU you can build is 800 square feet.

Keep in mind that these regulations are only for the San Jose area. Your locale may have similar requirements and restrictions, but no two jurisdictions are exactly the same, so you’ll need to do some research to learn about your local options.

Call your building and planning department to ask about permits, permissions, and other requirements to bring your granny flat plan to life. Or better yet, if you partner with ADU building specialists, we’ll gladly take care of the legal legwork for you.

Brainstorming Granny Flat Ideas

Now that we’re through the basics, it’s time to focus on the fun part — designing a granny flat your family members will love. Let’s talk about some potential granny flat layouts you may not have considered yet.

Studio Floor Plans

Perhaps you’re limited on space and you can only build a granny flat around 300+ square feet. Or maybe your family member loves the idea of an open floor plan with a lot of room to move around.

Rather than trying to cram several tiny rooms into a small flat, why not skip the room divisions and style it as a studio apartment?

This open-floor concept is ideal for a solo grandparent or a boomerang kid who appreciates contemporary minimalist designs. With no separation between the bedroom, living room, and kitchen, studios often feel much more spacious than you’d expect. All you need are the right furnishings — but we’ll get to that a bit later.

Studio layouts are ideal for anyone who doesn’t want to (or is unable to) spend a lot of time cleaning and maintaining the space. It’s less expensive to furnish, and the utility bills will also be lower than with a larger unit.

One-Bedroom Floor Plans

A classic one-bedroom granny flat plan is the most popular type of granny flat. Ideal for one occupant or a couple, this layout has everything they need to feel at home.

In this concept, the kitchen, living room, and dining area are open, giving the home a spacious feel. Meanwhile, there’s a separate bedroom for comfort and privacy, along with a full bathroom.

The great thing about this type of granny flat design is you can scale it up or down, depending on the amount of space you have to work with. A 400+square foot one-bedroom flat feels like a cozy cottage, while a 750+ square foot one-bedroom flat has plenty of open space for personalization.

Two-Bedroom Floor Plans

If you have enough space, the sky’s the limit for what you can achieve with a two-bedroom granny flat plan. This design feels closest to a traditional “home” and, if the layout is right, can be far more comfortable and functional.

For example, you can design a split bedroom plan with the kitchen, living area, or bathroom as a buffer between bedrooms. Or, to make space for a larger living room and kitchen area, you can arrange the bedrooms side-by-side.

You can make both bedrooms the same size, or you can turn one into a “master suite” while the other functions as a small office or guest room. There are no set rules about bathrooms either. You can have one full bath, one full bath and one-half bath, or two full baths if you have enough room.

Ideally, you’ll want at least 750 square feet of usable space if you’re thinking of a two-bedroom layout. But as modern tiny homes have shown us, you can do amazing things with small spaces.

Granny Flat Design: Traditional or Modern?

Speaking of amazing designs, what kind of style do you want your granny flat to have?

Some designs are more classic, with a rustic cabin or cozy cottage vibe. Others harken back to a particular time or place, perhaps capturing the Victorian era or the Tuscan lifestyle. Still others are ultra-modern, with oversized windows and minimalist furniture.

There are no right or wrong answers here, but you should consider who’s going to be living there. Your 20-something college graduate might not be as excited about Victorian design as your 80-year old mother-in-law. On the other hand, your mother-in-law probably won’t appreciate IKEA’s modern and functional (but not always comfortable) furnishings.

Like regular homes, you can construct a granny flat with almost any material. However, you need to consider the cost, the longevity, and the visual appeal of your chosen building material.

You don’t need to build a miniature version of your existing home, but you don’t want your granny flat to clash with it either.

6 Expert Tips for Designing a Granny Flat

Hopefully, by this point, you’re getting a clearer idea of your potential granny flat plan. You know what’s allowed in your area and how much space you have to work with. You’ve also decided between a studio, one-bedroom, or two-bedroom layout.

Now what? Now comes the best part — filling in all the little details to turn the flat into a home.

Of course, there are plenty of practical considerations to factor into your project too. For example, what’s the size, shape, and slope of your yard? How should you orient the granny flat to maximize natural light?

Most importantly, how can you design it to ensure your loved one will love living there? Here are our best tips to round out your granny flat plan.

1. Start With Orientation

At first glance, it’s easy to go with the most obvious answer. The front door should be close to the driveway, shouldn’t it? The bedroom windows should face the back of the property, right?

Not necessarily. More than just aesthetics are involved here. You also need to consider your climate, the amount of sunlight you do (or don’t) receive, as well as your current heating and cooling costs. Not to mention your city’s rules. In most cases, orientation is presided over by the city, with a professional working closely with them to make a case for where the granny flat can go.

General wisdom states that you want to make the most of both dominant wind direction and natural sunlight. In San Jose, for example, we enjoy 257 days of sunshine every year. It’s great for getting a tan, but it can be brutal on your energy bill.

If possible, try to plan so that the longest sides of the granny flat face north and south. This will capture more warmth and natural light in the winter while keeping the flat cooler during the summer months. Adding west-facing windows will also allow the flat to collect offshore breezes.

2. Porch & Patio Options

A good granny flat plan doesn’t just include the interior. If space allows, you should consider adding a porch or patio, or just a great outdoor space too.

Does your property have a lovely view of the mountains or a nearby park? Have you worked hard on your garden landscaping or swimming pool area? The occupant of your granny flat will love having a little patio or patio that faces the beautiful scenery. A lot can be done with a little in most cases.

You could choose to add a traditional covered porch or an open patio to offer direct access to the sun. You could also extend one wall to provide some protection from the elements, perhaps as a windbreak if your neighborhood tends to be breezy. Or a simple landing where a bistro table and some flower pots can rest, also makes a great outdoor environment to enjoy.

If you’re building the flat with a particular family member in mind, you could ask about their habits and preferences. Would they enjoy having their morning coffee on a sunny patio, or would they prefer a porch that faces the sunset? Would they most enjoy a traditional table-and-chairs set, or would they prefer a cozy porch swing or glider?

3. Be Smart About Storage

Most granny flats don’t have enough space to accommodate large closets, wardrobes, or pantry spaces. To ensure your loved one has enough space for their personal items, you’ll have to think outside the box when it comes to storage.

One idea is to go vertical by adding open shelves all the way up the walls. This provides ample space for photo frames, books, houseplants, and other items of decor. If you’re worried about clutter, you can always hide some shelves behind a tasteful cabinet door.

Carry this same idea over to the bedroom by creating under-the-bed storage space. Use rolling drawers, boxes, or other organizers to store seasonal or rarely-used items. You could also elevate the bed onto a platform to allow for decorative open shelving underneath.

To free up space in the bathroom and laundry room, you might consider pull-out hampers, rolling carts, or back-of-door storage. You’ll be amazed by how much space you can save by storing things under sinks, over doors, or even between the washer and dryer.

4. Maximize the Kitchen Area

Since we’re talking about saving space, let’s focus on making the kitchen as comfortable (but functional) as possible. Take a look at popular kitchen layout plans, keeping in mind that you can scale them up or down to fit the available space.

To create a great kitchen in a small space, look for “compact” versions of kitchen appliances. They look and work just like the regular versions, only smaller.

Compact refrigerators are 24 to 28 inches wide, saving valuable space over the standard 36-inch version. Look for a 20-inch kitchen cooktop range and you’ll save almost a foot of counter space over the standard 30-inch size. An 18-inch compact dishwasher saves six inches of width, while a dishwasher drawer saves an additional six inches of height.

Another terrific kitchen addition? Sketch a cozy breakfast bar or island bench into your granny flat plan. Not only is it a great place to socialize and eat meals, but it adds valuable storage space as well.

5. Choose a Light Color Scheme

We all have our favorite colors, and there’s nothing wrong with the occasional dark accent piece or bold pop of color.

In general, though, your granny flat design should feature light, warm, and neutral colors. Soft colors reflect more light than darker shades, which help to brighten and open up the living space. Be sure to include plenty of windows and sliding doors to invite natural light into the flat.

Think warm creamy shades of white or yellow and gentle shades of blue, green, or gray. Install LED lights in the kitchen and bathroom to provide ample lighting. In the bedroom and living room, you may opt for softer, warmer lighting to create a cozy atmosphere.

6. Make Safety a Priority

Most homeowners build a granny flat to accommodate an elderly relative or another family member that needs extra care.

As you design your granny flat plan, you might consider some of the following features:

  • Extra-wide corridors and pathways
  • Handholds and grab bars near the toilet and in the shower
  • A walk-in bathtub or shower bench
  • A medical alert device
  • A bed safety rail
  • Indoor cameras or a home security system
  • Senior-specific step stools
  • Smart devices (thermostat, doorbells, locks, etc)
  • Hardwood or tile flooring instead of rugs or carpeting

Of course, these are just some sample granny flat ideas. The exact modifications you choose will depend on the individual’s circumstances and health concerns. Your granny flat builder can provide more insight into the best options for your project.

Your Granny Flat Plan: From Concept to Reality

One thing is clear: granny flats aren’t just for grandma. The truth is that there’s an endless array of granny flat plans to suit seniors, students, couples, and everyone in-between.

We applaud you for being proactive and considering the long-term needs of your family. Bookmark this list of granny flat ideas to help you through the inspiration process.

And whenever you’re ready to turn your granny flat plan into an actual structure, we’re here to help. We specialize in customized ADUs throughout the San Jose area. We also offer affordable financing options to suit every budget and project.

Don’t leave your family’s fate to chance. Reach out to us today or give us a call to discuss your ideas!

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