Accessory Dwelling Units Are Changing How Families Live in the Upstate
Across the Greenville-Spartanburg region, homeowners are discovering that an accessory dwelling unit can solve problems they thought required selling their home and starting over. An aging parent who needs to live close by but values independence. An adult child saving for their first home. A need for rental income to offset a mortgage. A dedicated home office that actually feels separate from family life. These are the conversations that lead families to our door, and each one points to the same solution: a well-designed ADU on property they already own.
At Grander Construction, we approach accessory dwelling units with the same building science rigor and craftsmanship standards we apply to our custom homes. An ADU is a small building, but it is not a simple one. It requires its own foundation, its own utility connections, its own HVAC system, and code-compliant egress, fire separation, and accessibility considerations. Getting these details right is what separates a quality guest house from a glorified shed.
Zoning and Regulations in Greenville and Spartanburg Counties
Before you design an ADU, you need to know whether you can legally build one on your property. Zoning regulations for accessory dwelling units vary significantly across the Upstate, and the rules are evolving as municipalities respond to housing demand.
In unincorporated Greenville County, ADUs are permitted in most residential zoning districts, subject to size limitations, setback requirements, and owner-occupancy provisions. The ADU typically cannot exceed a certain percentage of the primary home square footage or a maximum gross floor area, whichever is less. Setback requirements from property lines are the same as for any accessory structure, usually five feet from side and rear property lines.
Spartanburg County has similar provisions but with different specifics. Some municipalities within both counties, including the cities of Greenville and Spartanburg, have adopted their own ADU ordinances that may be more or less restrictive than the county rules. The critical first step in any ADU project is a zoning verification with the relevant jurisdiction to confirm what is allowed on your specific parcel.
We handle this research for every ADU project we take on, because the rules can be complex and the consequences of building without proper approvals are serious. Unpermitted structures can result in fines, required demolition, and complications when you eventually sell the property.
Design Considerations for Livable Small Spaces
Designing a functional home in 400 to 800 square feet requires a different mindset than designing a 2,500-square-foot house. Every square foot must earn its place, and the layout needs to feel spacious despite the compact footprint.
Open floor plans work particularly well in ADUs, with the living area, kitchen, and dining space flowing together in a single room. High ceilings or vaulted rooflines create a sense of volume that makes the space feel larger than its dimensions suggest. Clerestory windows or skylights bring in natural light without sacrificing wall space for furniture placement.
Storage is the hidden challenge of small-space design. Built-in cabinetry, under-stair storage, wall-mounted shelving, and closet organizer systems maximize usable storage without consuming floor area. We often incorporate window seats with storage underneath, kitchen islands with cabinet bases, and bathroom vanities with full-depth drawers rather than open shelves.
The kitchen in an ADU needs to be functional for daily cooking, not just a token kitchenette. A 24-inch range, an 18-inch dishwasher, and a counter-depth refrigerator provide full cooking capability in a fraction of the space required by standard appliances. L-shaped or galley kitchen layouts maximize counter space and workflow efficiency in compact footprints.
Aging-in-Place Features
One of the most common reasons families build ADUs in the Upstate is to provide a home for aging parents. When this is the intended use, accessibility features should be designed in from the start rather than retrofitted later.
Zero-step entries eliminate trip hazards and accommodate wheelchairs and walkers. We typically achieve this with a gently sloped concrete walkway that meets the ADU threshold at grade level, with proper drainage to prevent water intrusion. Interior doorways should be a minimum of 36 inches wide, and hallways should be at least 42 inches to allow comfortable passage with a mobility device.
Bathrooms in aging-in-place ADUs need curbless showers with bench seating, grab bars at the toilet and in the shower, comfort-height toilets, and lever-style faucet handles. Non-slip flooring throughout the unit is essential. We also recommend installing blocking in bathroom walls during construction so that additional grab bars can be added later without opening up finished walls.
Lighting deserves special attention for older residents. Task lighting in the kitchen, bathroom, and reading areas should be bright and shadow-free. Rocker-style light switches at 42 inches above the floor are easier to operate than toggle switches at the standard 48-inch height. Motion-activated lighting in hallways, bathrooms, and exterior walkways adds both convenience and safety.
Rental Income Potential
For homeowners who do not need an ADU for family use, rental income is a compelling reason to build. A well-finished ADU in the Greenville-Spartanburg market can generate monthly rental income that substantially offsets the construction cost over time.
Long-term rental rates for quality ADUs in the Upstate currently range from approximately $900 to $1,500 per month depending on size, location, and finish level. Short-term rental through platforms like Airbnb or VRBO can generate higher per-night rates, but local regulations on short-term rentals vary by municipality and may restrict this option in some areas.
If rental income is part of your plan, design decisions should reflect tenant needs: a private entrance separate from the main home, dedicated parking, sound insulation between the ADU and the primary residence, and laundry facilities within the unit. These features make the ADU more attractive to tenants and reduce friction with your own household.
Utility Connections and Site Infrastructure
An ADU requires connections to water, sewer or septic, electrical service, and potentially natural gas. How these connections are made depends on your existing utility infrastructure and local code requirements.
Electrical service can be fed from the main home panel if capacity allows, or a separate meter and service entrance can be installed. A separate meter is advantageous if you plan to rent the ADU because it allows the tenant to pay their own electric bill. Water and sewer connections typically tap into the existing service lines, but the added demand may require upgrading the water meter or, in the case of septic systems, confirming that the existing septic capacity can handle an additional dwelling unit.
Internet and cable service are easy to overlook during planning but important for livability. Running conduit for data cables during construction is far easier and less expensive than adding it after the walls are finished.
How much does an ADU cost to build in the Upstate?
Construction costs for a quality ADU in the Greenville-Spartanburg area typically range from $150 to $250 per square foot, depending on finish level, foundation type, and site conditions. A 600-square-foot ADU might cost between $90,000 and $150,000 fully finished. This includes foundation, framing, roofing, insulation, HVAC, plumbing, electrical, interior finishes, and exterior finishes. Site preparation, utility connections, and permitting fees are additional costs that vary by property.
Can I build an ADU if I have a septic system?
Yes, but the existing septic system must have sufficient capacity to handle the additional wastewater load from the ADU. A septic system evaluation by a licensed professional is required to determine whether the current system can accommodate the additional dwelling or whether an expansion or separate system is needed. In some cases, the soil conditions on the property may limit septic expansion options.
Does an ADU increase my property taxes?
Adding an ADU increases the assessed value of your property, which will result in higher property taxes. The amount of the increase depends on the size and value of the ADU relative to your primary home. In Greenville and Spartanburg counties, the tax assessor will reassess your property after the ADU receives its certificate of occupancy. We recommend consulting with your tax advisor to understand the specific impact before beginning construction.
How long does it take to build an ADU?
A typical ADU project takes four to six months from permit approval to certificate of occupancy. The permitting process itself can add four to eight weeks depending on the jurisdiction and the complexity of the plans. Design and engineering work before permit submission usually takes two to four weeks. All told, most homeowners should plan for a six to nine month timeline from initial consultation to move-in.