Home Additions That Bring Great ROI in California

Homeowners add to their homes for several reasons
. Adding on more space for an aging relative, updating a home to suit modern needs, preparing for a growing family, or rejuvenating a space in hopes of a successful resale are just a few. Even if you’re not planning to sell any time soon, choosing additions that deliver the highest return on investment (ROI) is a wise move. 


Where you decide to add to your home will inevitably depend on where your home needs it most. If you upgrade and expand your kitchen but your home still lacks a primary suite, your investment may fall flat with prospective buyers. 

With that in mind, these numbers are reported from the Remodeling 2022 Cost vs Value Report for the Los Altos, California, area and are seen as stand-alone additions and remodeling projects. In other words, without context. The latest Cost vs Value Report reflects the value home buyers place on exterior additions and improvements, like outdoor living spaces, replacing siding, and adding stone veneer. Here we’ll talk more about additions as well. 


An outdoor living space can mean so many different things, from a simple deck to a chef-worthy outdoor kitchen and bar. At its most basic, the outdoor addition of a deck has an ROI of 68% if made of wood and 60% if it’s made of composite materials. These numbers are based on a 16 x 20-foot deck with built-in planters and benches, stairs of the same material, posts, railings, and balusters. The Cost vs Value Report estimates that in Los Altos, the all-wood deck would cost around $27K and the composite deck would cost roughly $33K. 

From there, costs will climb depending on how covered, weatherproof, or extravagant you’d like your outdoor living space to become. A porch would include extending your roof, possibly being screened-in, include a fireplace, have a deck extending from the porch for open-air grilling space, and even lead down onto a patio with a pergola with an additional lounge area. 

The ever-popular outdoor kitchen makes cooking and entertaining at home more fun and shakes up the usual indoor activity. This is why an outdoor kitchen can fetch an ROI from about 60% to 100%. The range is so wide because the data for outdoor kitchens is only now being collected, making it difficult to come to a more accurate number. The range of amenities is also pretty wide. An outdoor kitchen can have just a grill and a sink, or an entire suite of outdoor kitchen appliances that rival the indoor kitchen, and then some. 


The Cost vs Value Report divides some additions and remodels into two categories: midrange and upscale. More high-end trending finishes will give your kitchen more of a luxury feel but will yield a lower ROI compared to a midrange selection of finishes. Higher-end finishes are usually more personalized and can be specific to the homeowner’s style. Buyers are more open to updating on their own down the line with more universal styles. 

Adding onto a kitchen will include foundation, expansion of the roof, framing, electric, plumbing, and likely relocating mechanical systems. You can expect to pay at least $280 to $300 per square foot on top of the remodeling costs of the existing kitchen and can go beyond that based on the finishes you choose.  

In a midrange kitchen, the cabinetry is replaced with semi-custom wood cabinetry, a 3×5 foot island is installed, custom lighting, and all new appliances. What’s less appealing to many homeowners today, though, is that this level includes laminate countertops, a double basin stainless steel sink, and a standard single-lever faucet. In Los Altos, this remodel would cost around $100K with a 70% ROI. 

The Bay area luxury kitchen remodel takes the same 200-square-foot kitchen but replaces the cabinets with all high-end custom cabinetry with custom storage features, like slide-out shelving. The countertops are natural stone with ceramic tile backsplashes and underlit cabinets. This level also includes an island, a built-in refrigerator, a commercial grade range and other smart high-end kitchen appliances, a water filtration system, custom lighting, and durable wood-look ceramic tile flooring. 

This luxury upscale Los Altos kitchen could cost around $190K and give you a 58% ROI. To boost the ROI, stick to more timeless high-end finishes in neutral tones rather than the latest trending materials and finishes. If you’d like to add color to your kitchen via a trending color on the cabinets, for example, be prepared to have them repainted before showing your home. 


Adding a primary suite is an essential remodel for older homes since they’re usually lacking one. But if your home already has a large main bedroom with a walk-in closet, you’ll only need to consider a bathroom addition. Here, we’ll outline the costs associated with a full suite addition. 

Just as kitchens are categorized by midrange and upscale, so are primary suites. The midrange suite consists of adding 24×16 feet of space that includes a bedroom, a walk-in closet, a separate tub and shower with ceramic tile, and double vanity. This addition would cost around $240K and have an ROI of 68%. For luxury home additions that include smart features or higher-end finishes, this average cost would be higher.

The upscale primary suite addition offers a bit more space at 32×20 feet, which makes room for a sitting area and fireplace with built-ins and a wet bar. The walk-in closet and bathroom would feature custom storage. Also in the bathroom, you could expect a walk-in shower with a glass enclosure, natural stone tiles, a freestanding tub, separate vanities, and a commode closet for added privacy. The Report also includes radiant heating on the floors, smart lighting, and more sophisticated soundproofing. An addition like this in Bay area luxury homes will come to around $475K and offer a ROI of 55%. 


Bathroom additions often come along by pure necessity. Too many people sharing a bathroom, no comfortable place for guests, or anticipating another person joining the household are the main reasons. The Cost vs Value Report also divides bathrooms by midrange and upscale. The midrange is profiled as a 6×8 foot addition with a stone-topped vanity, a tub/shower combo with ceramic tile, commode, storage, and ceramic tile flooring. The average Los Altos price comes to $90K with a 64% ROI. 

An upscale luxury bathroom addition is outfitted like an upscale primary suite bathroom. This 10×10 foot space includes a glass-enclosed large walk-in shower with ceramic tile and body sprayers. It also features a freestanding tub, high-end fixtures, a natural stone-countertop double vanity, a closed-off commode closet, ceramic tile floor, custom cabinetry, and a radiant heated floor. This luxury bathroom is estimated at $150K and has a 60% ROI. 


It’s hard to say exactly how much finishing a basement will cost, at least with the precision as the other additions on this list. What we do know is that a finished basement of any kind can yield an impressive ROI of 70%. 

Basements can be as varied in amenities as outdoor spaces. At its very basic, it’s finished just enough to be extra storage space: walled in with minimal electric outlets and lights. At its most lavish, you can create a theater space, an entertainment den complete with TVs and a bar, or a guest suite. This could range from $30K to several hundred thousand dollars. 


Regardless of the improvements, you invest in your home, if the curb appeal is lacking, a buyer will assume the worst of the rest of the house. Essentially, while you’re planning a remodel, be sure to invest in improving your home’s exterior as well. 

Adding stone veneer, replacing your garage door, and replacing your siding with new vinyl or fiber-cement siding will have the biggest ROI along with other additions. Ask an architect or home builder about the exterior upgrades you should add to your remodeling project to make the best impact on your home’s value in the eyes of a buyer. 

K.C. Customs is a custom home builder and remodeler in Los Altos, California. With a focus on service, craftsmanship, and attention to detail, K.C. Customs centers your design goals and delivers a luxury home that exceeds expectations, every time. Contact K.C. Customs to schedule a consultation to discuss your home’s potential addition. 

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