A second home on the lot you already own
An accessory dwelling unit, or ADU, is a small, complete home on the same lot as your main house: its own kitchen, bathroom, sleeping area and entrance. Around Asheville people build them for a parent who wants to live close but not under the same roof, for a grown child, for a caregiver, or as a long-term rental that helps carry the mortgage. Some are attached to the house, some stand on their own, and some start life as a garage.
An ADU is new construction at a smaller scale. It needs a foundation, framing, a roof, its own utilities and a permit, and it goes through the same inspections as a house. We build houses in Western North Carolina every week, so we treat an ADU the way we treat a house, not as a large shed.
Three ways to build one
- Detached ADU. A separate cottage in the back or side yard. The most privacy and the most flexibility for rental, and usually the highest cost, because it needs its own foundation, roof and utility runs.
- Attached ADU or in-law suite. A self-contained unit built onto the existing house, with its own entrance and kitchen. It shares a wall and often some utilities, which can bring the cost down.
- Garage or basement conversion. Turning existing square footage into a living unit. Where the slab, walls and roof are sound, this is often the least expensive path, though insulation, egress, ceiling height and plumbing decide how far it can go.
Mountain lots change the plan
On flat suburban lots an ADU is mostly a design question. Here it is a site question first. Four things decide where a unit can go and what it costs:
- Slope. Most lots around Asheville fall away from the house. A steep site means stepped footings or a walk-out foundation, retaining walls and careful drainage so water goes around the new unit, not into it.
- Sewer or septic. On city sewer, the question is how far and how deep the new line runs. On septic, the system has to be permitted for the added bedrooms, and that check comes before design, not after.
- Water and power. Some units can tie into the existing service, others need a separate meter or a larger electrical service. Trenching across a sloped yard is real cost and belongs in the price from day one.
- Access and parking. Crews, concrete trucks and later the occupant need a way in. On a narrow or steep driveway, that shapes the whole layout.
Zoning and permits
ADUs are allowed in many residential zones in Asheville and Buncombe County, but the rules differ by jurisdiction and by zoning district: how large the unit can be, where it can sit relative to property lines, how many can share a lot, and what parking is required. HOA covenants can add their own limits. Before you pay for drawings, we check your lot against the rules that apply to it, and we pull the permits and meet the inspectors once the design is set.
Family use or rental income
How the unit will be used changes the design. A unit for an aging parent wants a no-step entry, wider doors, a curbless shower and blocking for grab bars. A rental wants durable finishes, separate utility metering where practical, and a layout that works for someone you do not know yet. We plan for the use you have in mind now and the one it may have in ten years.
Timeline and budget
A garage conversion can be finished in a few months. A new detached ADU typically runs five to eight months on site after permits, depending on foundation work and utility runs. Costs follow our additions, generally $250 to $400 per square foot, so most detached ADUs land in the low-to-mid six figures, and conversions of existing space come in lower. Every site is different, so we give you a fixed, written price after a site visit, not a guess over the phone.
Where we work
Asheville, Hendersonville, Arden, Candler, Fletcher, Weaverville, Black Mountain, Mills River, Brevard and Waynesville.
