Designing accessory dwelling units and short-term rental spaces that work as well as they look.
Asheville’s short-term rental market has made ADU design one of the most requested residential services in WNC, and for good reason. A well-designed accessory dwelling unit on a residential property can generate significant rental income, create valuable long-term housing flexibility, and add more to the property’s appraised value than almost any other residential investment of equivalent cost.
The complication is that ADU design in the Asheville area involves more variables than most homeowners anticipate before they start. Lot size, zone designation, setback requirements, utility capacity, impervious surface limits, and short-term rental permitting rules all affect what is possible on a specific parcel — and those rules differ between unincorporated Buncombe County and the City of Asheville, and again between the city and incorporated towns like Weaverville, Black Mountain, or Hendersonville.
Form & Function has designed ADU and short-term rental projects across this regulatory landscape and understands how to evaluate a parcel’s realistic ADU potential early in the process — before a client has committed money to a design direction that turns out not to be permitted. Contact the studio to discuss your property and what an ADU feasibility assessment would involve.
An accessory dwelling unit (ADU) is a secondary residential unit located on the same parcel as a primary dwelling. In Buncombe County and the City of Asheville, the definition encompasses several distinct types of residential accessory structures, each with its own set of dimensional and regulatory requirements.
Detached ADUs are freestanding structures on the same lot as the primary home — a separate cottage, a converted outbuilding, or a purpose-built guest house. These offer the most privacy and design flexibility but also the highest construction cost, because they require their own foundation, roof system, utility connections, and exterior envelope.
Attached ADUs share at least one wall with the primary residence — a wing addition, a connected carriage house, or a living space added above an attached garage. These tend to cost less than detached units but offer less separation between the primary home and the rental unit, which affects both guest experience and the owner’s privacy.
Internal ADUs are created within the existing footprint of the primary home — a basement conversion, an in-law suite, or a finished portion of an existing structure that gets separated into an independent unit. These are often the lowest-cost ADU option because no new foundation or exterior envelope is required, but they depend on the existing structure having the right spatial conditions to work.
Garage apartments — living space built above a detached garage — are a common ADU type in WNC and occupy a middle ground in cost and configuration. They typically require more structural engineering than internal ADUs but less than fully detached cottages, and they provide useful separation between the guest space and the primary home.
In Buncombe County, ADUs are generally permitted in most residential zones with a minimum lot size requirement and setback compliance. The City of Asheville has its own regulations that have been updated in recent years to make ADU permitting more accessible. Reach out to discuss your specific parcel — zoning and ADU eligibility are property-specific and require a parcel-level assessment.
The Asheville short-term rental market is competitive enough that design quality has become a real differentiator. The listings that consistently earn strong bookings, high ratings, and premium nightly rates in WNC share a set of design characteristics that are worth understanding before a project is designed — not after.
Spatial efficiency matters more in short-term rentals than in primary residences. Guests use every square foot of a rental, which means dead space — corridors that lead nowhere, awkward room proportions, bathrooms too small to be comfortable — registers immediately and shows up in reviews. The Riceville Road residence, recognized by Architectural Digest as one of the most striking Airbnbs in Asheville, succeeds partly because no space was wasted: the 1,600-square-foot home was designed so that every niche and corner has a specific purpose, which makes the home feel larger and more considered than its square footage suggests.
View capture is the single most common differentiator between strong-performing Asheville rentals and average ones. Properties with genuine Blue Ridge Mountain views command meaningfully higher nightly rates than comparable properties without them — which means designing window placement, outdoor living areas, and interior sightlines to maximize view exposure is a direct revenue decision, not just an aesthetic one.
Outdoor living space has become essential in the WNC short-term rental market. Covered decks, screened porches, hot tub pads, fire pit areas, and outdoor dining spaces all extend the usable square footage of a rental property and appear in the listing photography that drives booking decisions. Designing these spaces with the same intention as interior spaces — not as afterthoughts, but as primary amenities — produces properties that photograph well and deliver on what the photos promise.
Material durability is a practical consideration in rental design that differs from primary residence design. Finishes, fixtures, and surfaces in a short-term rental take more use and abuse than those in a private home, which means the design should specify materials that hold up to heavy turnover while still meeting the aesthetic standard guests expect at the price point the property is targeting.
The comparison between a detached ADU and a basement conversion is one of the most common questions in the WNC residential remodel market, and the answer depends on variables specific to each property.
A detached ADU typically produces higher rental income and adds more appraised value than a basement conversion of equivalent investment, because it offers more separation, more privacy for both the owner and the guest, and more design flexibility. It also costs more to build — a detached structure requires its own foundation, envelope, and utility connections.
A basement conversion costs less in most cases, particularly when the existing basement has sufficient ceiling height and already has rough-in plumbing. The trade-off is a guest experience that feels more connected to the main house — which matters more in some markets and for some rental formats than others. In Asheville’s short-term rental market, where guests are often specifically seeking standalone cabins and cottages, the separation a detached unit provides tends to translate into better reviews and higher nightly rates.
The right answer depends on what the property allows, what the budget supports, and what the intended use is. An ADU intended for long-term rental or multigenerational family use has different design requirements than one built primarily for Airbnb revenue. Reach out to discuss your specific property and goals — a site visit and feasibility conversation is the most reliable way to evaluate the options honestly.
The gap between an ADU that gets consistent bookings at premium rates and one that sits empty between occasional reservations is often a design gap — not a marketing gap.
Guest houses that perform well in the Asheville market share a set of qualities that go beyond aesthetics. They feel private — the guest space and the primary residence have genuine separation, not just a locked door between them. They feel complete — every function a guest needs is available without improvisation or workaround. They feel intentional — the design makes the guest feel that the space was made for them, not adapted from something else.
This last quality is the hardest to achieve by renovation and the easiest to achieve by design. A purpose-built guest cottage, designed from the start as a short-term rental, can achieve all three qualities more reliably than a converted basement or a repurposed room. The Riceville Road project demonstrates what happens when a short-term rental property is treated as a serious piece of residential architecture — it produced a home that guests describe in terms that go beyond “comfortable” and into “memorable.”
Read more about Form & Function’s residential design approach and how the same process that produces exceptional primary residences applies to guest houses and short-term rental design.
The Riceville Road residence started with a specific brief: create a modern mountain retreat on an Asheville lot that could function as both a high-quality short-term rental and a private residence. At 1,600 square feet, the home was not going to compete on size. It had to compete on experience.
The design team’s response was to treat every decision — material choices, spatial flow, window placement, the relationship between interior and exterior — as a direct investment in guest experience. Polished concrete floors that photograph well and hold up to rental traffic. Cypress wood siding and corten steel panels that age gracefully in WNC’s climate rather than requiring maintenance between guest stays. Large, strategically positioned windows that turn Blue Ridge views into the home’s primary interior feature. An open floor plan that makes 1,600 square feet feel considerably larger than it is.
The result was recognized by Architectural Digest as one of the most beautiful Airbnbs in Asheville — which translated directly into booking performance and nightly rates that the square footage alone would not have supported. See the full project detail and explore the residential portfolio for other examples of Form & Function’s short-term rental and ADU work across WNC.
The Asheville short-term rental market peaks in summer and fall — leaf season, festivals, and outdoor recreation all drive demand for well-designed short-stay accommodations across Buncombe County and surrounding areas. The properties that consistently book out during peak periods share a few identifiable qualities: distinctive design, genuine mountain views or natural settings, strong outdoor living amenities, and a level of finish quality that photographs as well as it feels in person.
Most of those properties were not accidents. They were designed — with intention, with knowledge of the market, and with an understanding of what guests in this specific market are choosing between when they make booking decisions. If you are considering an ADU or short-term rental project in WNC, the design decisions you make now will determine where your property sits in that competitive landscape for years. Meet the Form & Function team and discuss what a well-designed ADU could look like on your property.
ADU construction costs in WNC vary widely by type and size. A basement conversion with existing rough-in plumbing may run $80,000 to $150,000 depending on finish level. A detached cottage or garage apartment typically runs $150,000 to $350,000 or more, depending on size, site conditions, and finish quality. These figures reflect recent construction cost ranges in the Asheville market and will vary based on your specific site, contractor, and design choices. Architect fees are typically calculated as a percentage of construction cost or as a fixed fee based on scope.
The City of Asheville regulates short-term rentals separately from ADU zoning. As of 2024, the city requires a short-term rental permit, and regulations around owner-occupancy requirements, permit caps by neighborhood, and enforcement have evolved in recent years. Unincorporated Buncombe County has its own short-term rental framework with different requirements. Before designing an ADU specifically for short-term rental purposes within city limits, confirming current regulations with the City of Asheville Planning Department or with a knowledgeable architect is strongly recommended. Form & Function can assist with this assessment as part of early project conversations.
A detached ADU design and permitting process in Buncombe County typically runs 4 to 8 months from initial design through permit approval, depending on project complexity and the county’s current review workload. The City of Asheville’s permitting process has its own timeline, typically 6 to 12 weeks for residential review after submission of complete documents. Construction follows permit approval and runs 4 to 8 months for most ADU types. Total timeline from design start to move-in typically falls between 9 and 18 months.
Not always, but often it makes practical and regulatory sense. In Buncombe County and the City of Asheville, the utility connection requirements for ADUs depend on the type of ADU, the existing service capacity of the primary residence, and the jurisdiction’s requirements for rental units. Separate metering simplifies the landlord-tenant relationship for long-term rentals and allows for separate billing in short-term rental operations. Form & Function coordinates utility feasibility assessment as part of the early project process to ensure the design direction reflects what the site’s utility infrastructure can support.
Buncombe County’s ADU size regulations set maximum square footage limits for accessory dwelling units relative to the primary residence and lot size. The specific limits depend on the zoning district and whether the ADU is detached or attached. The City of Asheville has updated its ADU regulations in recent years to allow larger ADUs in certain zones. A parcel-level assessment — looking at your specific zone, lot size, existing footprint, and setbacks — is the most reliable way to determine what size ADU is permitted on your property.
