A higher cost of living, limited housing, the undisputed need for a quiet home office or a private pad for visitors—the list of reasons why the modern homeowner doesn’t just want but needs ample living space goes on and on. While we’d all love to escape to the A-Frame cabin of our dreams, secondary dwellings have become an increasingly popular and accessible option when that extra room is simply too hard to find.
Whether you call it a sidekick unit, an in-law suite, granny flat, or simply an ADU, accessory dwelling units are a viable and perhaps, not-so surprisingly, design-focused way to make the most of your space (budget willing of course). If you’re in the market for a prefab ADU, this guide can help you better understand the process, costs, and narrow down the options to score the very best tiny, but mighty, backyard home.
What Is an ADU?
An Accessory Dwelling Unit (ADU) is a self-contained living space that is either inside, attached to, or detached from a single-family home on a single lot. ADUs have a small floor plan (generally from 150 sq ft on up to 1,000 sq ft or more—local regulations may dictate the max size your own backyard can legally host) complete with designated areas for living, sleeping, sanitation, and eating, but don’t go labeling it a tiny home. Even though tiny homes can certainly be ADUs, not all ADUs are tiny homes, because, by definition, an accessory dwelling unit is an additional structure on a single-family property—not an off-site tiny cabin in a remote and beautiful location far, far away, but those are great too.
Compact, modular, and often prefabricated off site, ADUs are most commonly used as a secondary dwelling on the homeowner’s property. They’re ideal as a guesthouse, home office, or as close and convenient housing for family members without having to sacrifice your privacy (or worse, share a bathroom). Depending on your town’s zoning laws, these backyard homes can also be used to generate rental income as a short or long-term rental unit, too. The Airbnb or Vrbo option is especially helpful for generating additional income. Either way, an ADU can and likely will increase your property value.
For these reasons, they’ve become a popular and legal way to add affordable housing units in overcrowded areas—take California, for example, which recently amended its zoning laws and lifted restrictions on ADUs making it easier to create secondary housing units—during a time when home costs are high and living space is hard to come by. However, like any additional structures being added to your property, the size, location, use, and occupancy of an ADU depends entirely on the local laws and building codes, full stop. To find out if it’s legal to build an ADU on your property, and how you’re allowed to use it, check the county and city zoning laws or take a trip to the municipal clerk’s office for more information. If your jurisdiction doesn’t have specific laws for ADUs, follow the state regulations for guidance. This process will be tedious and perhaps even frustrating at times, as most counties are slow to adapt. Good luck!
What Are the Benefits of a Prefab ADU?
Short for “prefabricated”, prefab structures are homes that are designed and built at a factory before being delivered to the building site for construction. So, having a professionally designed, ready-made home made in a climate controlled facility arrive at your doorstep is already a major perk and time saver. Additionally, a prefab ADU design is on average, 10-20% cheaper than new construction, and once it’s delivered, may only need a few weeks to assemble in comparison to the months-long process of building from the ground up. Plus, many of the variables that can deter the building process, like weather, finding and hiring reliable workers, and sourcing materials also disappear when you buy a prefab ADU. And since many of today’s prefab homes are designed with a modern form, you get all the benefits of a prefab ADU—a quicker build, a slightly lower cost, and the opportunity for semi-passive income—all without sacrificing aesthetics.
Is a Prefab ADU Cheaper Than New Construction?
Yes, it can be; which is one of the reasons why ADUs have become a popular solution for adding affordable housing. Small prefab ADU models generally cost less than new construction, and you won’t need to hire an architect, an engineer, or pay for raw materials like you would for a custom home. In some cases, solar panels are included in the total cost, saving you money on electricity in the long run. If you’re new to this, consider hiring a general contractor who is savvy to the local zoning laws to save a lot of time, and potentially money, to make sure you’re doing it right the first time.
Whatever you decide, a prefab ADU has far more pros than cons when it comes to providing sustainable and affordable housing or an on-site secondary dwelling for homeowners, and today’s design-forward models are bound to please anyone with high-end taste in architecture.
9 Great Prefab ADU Manufacturers Available in North America and Europe
Created in collaboration with design publication Dwell, Danish designers Norm Architects, and prefab studio Abodu, the stylish yet decidedly functional prefab ADU project boasting an airy interior space with a kitchen, built-in storage and an impressive 12-foot folding glass wall to usher in the outdoors. The versatile 540-square-foot unit is wrapped in sustainable cedar siding with a durable metal roof and arrives fully finished with fixtures, appliances, and even a dedicated project manager to ensure a smooth installation process.
Pricing starts at $389k
Run by Airbnb co-founder Joe Gebbia, the freshly-launched prefab project Samara offers one tiny home with two different floor plans, called The Backyard, that are built to satisfy both ADU standards and discerning design lovers alike. Each comes fully-equipped with appliances and solar panels for energy efficiency.
Pricing starts at $289k
A modest British Columbia-based operation launched in 2020, Aux Box specializes in no-fuss plug-and-play prefabricated structures so buttoned up you rarely need a permit to plop one down in your own backyard. Aux Box builds each prefab ADU on Vancouver Island and ships most anywhere in North America, with models ranging from 97 sq ft up to 588 sq ft.
Pricing starts at $28k
Koda Loft by Kodasema offers a minimalist shelter that maximizes space by building up. The multi-level unit is billed as a moveable timber frame home with an attractive dark wood exterior that channels Nordic design, making it easy to squeeze two bedrooms into a small footprint. Both the Koda Loft and its smaller counterpart, the Koda Loft Micro, are outfitted with a kitchen, bathroom, and living area.
Pricing starts at $149k
Based in Southern California, Kithaus created their unique prefab modular homes as a direct response to the need for ADUs in California. Precision-cut from a lightweight and ultra-durable aluminum material, it takes cues from post and beam architecture to make a small interior (the k3 model is a mere 120 sq ft) feel spacious with floor-to-ceiling windows and an open-concept floor plan. Modules come complete with plumbing, LED lighting, and the option to upgrade with solar panels, and you can customize to your heart’s content.
Pricing starts at $32k
Prefab manufacturer Studio Shed offers aspiring ADU homeowners a way to design a bespoke backyard dwelling from the floorplan to the cabinetry, with choices between for countertops and flooring (plus more). Design and price out your own ADU with with their configurator, the Summit Series, which allows users to riff on their prefab models or dream up one entirely their own.
Pricing starts at $28k
The Bay Modular
From a tiny 256 square-foot dwelling to a roomier shelter with a 648-square-foot floor plan, the Bay Modular’s Solo Series offers well-designed prefab ADUs in a range of sizes. Start with their standard sleek, modern layout and get DIY-ing by choosing your own interior and exterior finishes to customize the look.
Pricing starts at $121k
What if you could simply click and ship a move-in ready prefab ADU right to your door? Manta North has brought that vision to life with two customizable modern cabins, Ray and Slope, that can be delivered and set-up in a single day. Designed to meet the highest energy efficiency standards, they are an aesthetically-pleasing and sustainable addition to your property.
Pricing starts at $210k
All four of Bunch Design’s ADU homes are bright and airy, sun-filled dwellings that cleverly use clerestory windows, high-stepped ceilings, and sliding glass walls to open up even the smallest one-bedroom ADU design. Contemporary yet cozy, these house plans are versatile enough to be a studio or suite, and what’s more, the company will even provide support for the permit application and permit process to ensure a smooth, successful build.
Pricing starts at $250k