ADU Guide

The Best Interior & Exterior Finishes for Your ADU

Whether you are building a rental ADU or a luxurious retirement ADU, your interior and exterior finishes will impact how your ADU turns out. We cover the best interior and exterior finishing options for your ADU project.

Jimmie SandmanDecember 16, 2021

You have just decided to continue moving forward with your ADU after choosing the right floor plan and designer for your project. Great work! Beyond the concrete, timber, and drywall that go into the structure of your accessory dwelling unit, finishes and finish materials really make no two ADUs alike.

Your exterior and interior finishes for the ADU are what residents, tenants, and visitors see every day in the housing unit. So how do you choose what’s best for your ADU? We decided to bring in ADU expert and homeowner advisor Jimmie Sandman to help.

Prior to helping hundreds of homeowners through their ADU journey with an empathetic touch, Jimmie worked as a carpenter on residential construction projects across the San Francisco Bay Area. His on the ground experiences give him a unique perspective in the world of residential ADU construction.

Let’s hear from the expert!

Three Common ADU Finishing Levels

From speaking with homeowners across the Bay Area, we have noted that folks tend to fall into one of three categories when it comes to choosing their ADU’s finishes:

  • Standard Finishes: ADUs on a strict budget. Most common for ADUs intended to be rentals or return on investment-focused investors.
  • Standard Plus Finishes: ADUs with some budget for a few upgrades. Usually, we see Standard Plus finishes in ADUs with more flexible use cases, such as guest houses, age-in-place options, family and friends, and the potential for rental income.
  • Premium Finishes: Designer ADUs for family, retirement, or guest spaces, often matching the existing home. These are high end ADUs for high end homes or situations.

While these are generalizations, we have found these general groupings to be pretty consistent across our homeowners. Of course, many folks span multiple levels of finish with their choices—a homeowner who wanted a rental ADU but also a luxurious glass wall is one that comes to mind—and that’s certainly possible when you work with a custom ADU provider like Cottage.

This flexibility in your finishing options is a real advantage for the custom ADU approach. You can really decide what is best for your ADU use case with each finish option as opposed to the rigid choices of prefabricated or modular ADU companies.

Standard: The No-Frills, Economical ADU

With the 2020 ADU regulations coming into effect across California, perceptive homeowners and property investors immediately seized the opportunity to build and rent out their ADU unit(s). Some have gone so far as to build economical duplexes with ADUs in backyard spaces.

If you are looking for ADU rental income or the best bang for your buck for your custom space, there are a few ways to add quality finishing touches without breaking the bank.

Exterior Finishes

  • Roofing Material: We typically recommend 30-40 year composition shingle roofs, which is standard for residential construction.

    • Alternatively, a torch down or built-up-roof solution is standard for roofs with a pitch lower than 2/12 or a flat roof. This is also common in Los Angeles for Spanish-style homes with flat roofs.
  • Exterior Wall Finish: Stucco tends to be the best balance of cost and longevity, as cheaper options such as vinyl siding may save you up front but have a shorter lifespan. This isn’t a great outcome if you are hoping to earn top rental income for the long term.
  • Entry Doors: Building code requires that an ADU have at least one single swing door for entry and exit. If sliding glass doors are your preferred choice, it is important to note that an additional swing door will be required.

ADU Front Door Entry

Interior Finishes

  • Lighting: The most cost effective choice for lighting is a surface mount fixture, which provides versatility in light coverage and fixture style.
  • Flooring: When pets or active kids are part of the equation, luxury vinyl plank (LVP) is a great flooring solution. Gone are the days of rolling out cheap vinyl sheet flooring - over the last 10 years, vinyl flooring has greatly improved as a product. LVP is now installed in pieces, just like a true hardwood floor, and each plank is offered in a range of wood grain and stain patterns with faux wood texture. This scratch-proof, waterproof, and highly durable flooring is a great starting point for most ADU projects.
  • Doors & Windows: Vinyl windows are the industry standard and come in a wide variety of sizes and operational mechanisms (sliding, awning, double hung, fixed, etc.). They are easy to install and easy to replace if future repairs need to be made.
  • Bathroom: Tile bathrooms are standard with Cottage. Pricing can range from $3-4/square foot and up to $10 or even $20/square foot for tile. The difference in quality is minimal, but a wider variety of material (ceramic, stone, porcelain), texture/finish, or tile sizing is available with higher cost selections.

    • An alternative to tile is to continue the luxury vinyl plank flooring into the bathroom. LVP is durable and waterproof, and the single flooring material selection through the ADU can reduce labor and material costs for the project.

ADU Bathroom Interior

  • Kitchen: So many choices! Cabinet style, drawer and door pull hardware, countertop material, backsplash style and material, and faucet fixtures offer many places to choose from. Cottage provides guidance in the form of pre-selected kitchen design packages, which can help keep your decisions to a minimum.

    • The most affordable sink option is an over the counter stainless steel sink—easy installation and simple for future repairs or modifications.
    • All Cottage kitchen sinks come standard with a disposal.

ADU Kitchen Fixtures and Finishes

  • Appliances: Appliance packages for an ADU can range widely. A small ADU with basic appliances from a brand like Whirlpool can cost as little as a few thousand dollars.

    • When ROI or overall budget is the focus of an ADU build, a base appliance package will serve your needs quite well.
    • Cottage typically recommends brands like Whirlpool or Frigidaire, both of which are reliable brands that come in a variety of appearances.

Standard Plus: Flexible ADU Use Cases - Family, Friends, Maybe More

Multi-generational living is often a key reason why homeowners come to Cottage to build their ADU. Take Bob and Leslie for example; these Los Altos residents wanted to build a 1 bedroom ADU in their backyard for their adult daughter instead of having her pay thousands of dollars a month to rent a cramped South Bay apartment. Or take these Castro Valley homeowners, whose 2 bedroom, 1 bathroom, 750 square feet ADU is perfect for rental income or for the couple to live in when they get older.

These ADUs are examples of Cottages that prioritize flexibility. ADUs with multiple potential use cases are often the best choice for single family homeowners - the unit can function as additional space for the family or more distant relatives and has the flexibility to function as an affordable, high-quality housing unit at other points in the ADU’s lifecycle. Let’s dive into a few recommendations we make to homeowners like these:

Exterior Finishes

  • Roofing Material: If preferred, a more substantial 50 year presidential shingle is an option, but a 30-40 year shingle is still a great choice and the most popular option.
  • Wall Finish: A textured and colored stucco is a good option for an ADU’s exterior finish. Alternatively, Hardie Board siding (which can be installed as horizontal planks or in a board and batten style) offers incredible durability and mimics a traditional wood siding look. The cement fiberboard composition of Hardie Boards offers a high level of fire resistance as well.

    • Board and batten, composed of wood or Hardie Board sheeting and detailed with 2” boards running vertically on the surface, is a popular choice for a modern farmhouse aesthetic. It’s also more cost effective than redwood or cedar horizontal siding.
  • Entry Doors: French doors are the most common upgrade for exterior doors. They satisfy the swing door code requirement and can provide more light and an open feeling to the ADU. Common French doors are full light panels (glass with a 6-8” wood trim) or mullioned doors (glass panels with cross sectional wood accents to create a grid).

Exterior French Doors

Interior Finishes

  • Lighting: A mix of recessed lighting in the living room and kitchen areas with surface mounted fixtures in the bedroom and bathroom are recommended as a cost-effective lighting solution for these ADUs.
  • Flooring: Engineered hardwood flooring is the most common flooring option for Cottage ADUs. Composed of multiple layers of plywood and topped by a layer of finish wood (commonly oak or maple), engineered hardwood floors are a cost-effective way to achieve a real hardwood look and feel. Surprisingly, engineered hardwood is less expensive and more durable than hardwood.
  • Doors & Windows: Fiberglass windows offer a level up in quality, which comes with an increase in cost but greater flexibility when it comes to color selection and the ability to customize paint color.
  • Bathroom: No need to spend exorbitant amounts of money on tiling your bathroom. There are plenty of quality tile solutions within the $5-6/square foot range. Consider managing costs with a ceramic shower pan with tile walls in the bathroom, rather than a full tile shower.
  • Kitchen: The most common sink in our ADUs is an under-mounted stainless steel sink. Sitting flush under the countertop, it makes for easy cleaning and smooth lines around your sink area.
  • Appliances: LG, GE and Samsung are great options for kitchen appliances. By going with one brand for your appliance package, you are not only able to save money but keep future maintenance needs simple with a one stop shop for repair services.

Premium: Luxury ADUs to Match The Main Home

Some homeowners are looking for their ADU to be 100% custom, luxurious, and up to the quality of their also luxurious main homes. This Los Altos retiree, for example, wanted to build a massive almost-1200 square foot ADU to move into while still owning the existing house.

Without the need for 4-plus bedrooms and bathrooms but still wanting to live in the same neighborhood, a luxurious backyard Cottage becomes a great option for downsizing retirees or parents looking to rent out the main house or pass it on to younger family members. Yet, the downsized square footage does not need to come with downsized expectations.

There are some common finish selections that are common for homeowners thinking about these more premium and custom options:

Exterior Finishes

  • Roof Material: The 50 year presidential shingle is the most durable and substantial composition shingle roof option.

    • Metal roofs, often referred to as “standing seam roofs”, have also gained popularity. The cost of such a roof can range anywhere from $8-15,000 more than a traditional shingled roof
  • Wall Finish: Cedar shingle, horizontal redwood siding, and smooth stucco are the most common premium exterior finishes for our ADUs. A combination of smooth stucco and cedar siding can give your ADU a beautiful modern look.
  • Entry Doors: Large sliding or accordion glass doors are a go-to option to make a statement for your ADU entry. They provide that famous Californian indoor-outdoor living when connected to a backyard or deck space and allow for tremendous light into a space. If the only entrance to the ADU is the large glass panel wall, then one of the panels must function as a swing door by code.

ADU Roofing material

Interior Finishes

  • Lighting: Recessed lighting can provide sleek lighting throughout a space—typically selected in living rooms and kitchens. The cost difference between recessed and ceiling mounted lighting can be substantial, as a single recessed light can costs $2-300 more and light a much smaller area than a single comparable surface mounted light.
  • Flooring: Engineered hardwood flooring is being installed in high end, multi-million dollar homes and is an excellent premium flooring choice. That said, tried and true hardwood flooring is a common option for our premium ADUs. These floors will stand the test of time, with the ability to sand and refinish for decades to come.
  • Doors & Windows: Fiberglass windows, can be made in a more modern style akin to high-end aluminum or bronzed aluminum styles. Because Title 24 energy regulations in California make metal-framed windows difficult to permit, fiberglass is the upgrade of choice for our premium ADUs.
  • Bathroom: Stone and porcelain tiles come in a wide variety of looks and textures. Porcelain is more durable than a traditional ceramic tile and stone (whether it’s a slate or marble) is not only the most durable option but can make the biggest statement when it comes to the color and texture of your ADU bathroom.

    • Large bathrooms can accommodate a dual basin vanity (“Jack and Jill”) and are a great option in high end bathrooms where space is not a constraint.
  • Kitchen: Farmhouse ceramic sinks have become popular—examples of which can be seen all over Pinterest, Instagram, and in Dwell magazine. They offer a unique look and a large, open basin for washing. In many of our premium ADUs, an undermount stainless steel sink is still the go-to option.
  • Appliances: Thermador and Sub-Zero fridges are the crème de la crème of the cold food storage world. When it comes to cooking, Viking and Wolf ranges are the preferred choice of professional chefs and foodies who want to cook on the highest level equipment. For a full size kitchen, going with top of the line appliances can cost upwards of $12,000 more than other basic options.

ADU Interior Space

What are the Right ADU Finishes for My Needs?

With so many options to choose from when you take the custom approach for your ADU, we believe it’s important to have experts in your court from planning to executing your project. At Cottage, we believe in designing your custom, stick-built ADU in a cost-effective and smart way to give you the best bang for your buck. Whether you have a huge budget or a small one, complex needs or a simple single use case, we are here to help advise on the best finishes and design so you can get the most out of your ADU project..

Need advice for the finishes in your future ADU or want to learn more? Click the "Get Started" button on the top right hand corner to get a Free Consultation and Estimate Today.

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