Thinking about an ADU on your Greenville lot?

 

Inside City of Greenville limits, the Development Code allows accessory dwelling units (ADUs) — a smaller second dwelling on the same lot as your main house — with certain limits. The unit is capped at 1,000 square feet, someone who owns the property generally has to live in either the main house or the ADU, and the ADU still has to meet your zoning district’s setbacks, height, and building-coverage rules. Those last pieces are why a lot of smaller city lots won’t work. Outside city limits, Greenville County (and other towns) run different rules, so the address matters before the floor plan does.

What people usually mean by “ADU”

An ADU is a second dwelling on the lot you already own. Folks call them backyard cottages, garage apartments, in-law suites, or carriage houses. Around Greenville we hear the same three reasons over and over:

·        Keep aging parents or adult kids close, with their own front door

·        Guest space that doesn’t turn the main house into a hotel

·        Longer-term rental help on the mortgage, where the rules allow it

Short-term rentals are a separate conversation. In City of Greenville residential districts, ADUs are generally not a path to Airbnb-style stays — the Development Code conversation around adoption was clear that residential short-term rentals stay restricted.

City of Greenville: the rules that matter

We’re talking city limits here — the Greenville Development Code that took effect in 2023 — not Greenville County and not Greer / Simpsonville / Mauldin on their own books.

From how the city framed ADUs when the code updated (and how planning staff described the balance they were striking):

1.      Size. The ADU itself tops out at 1,000 square feet. Local summaries of the code also tie size to the main house (you don’t automatically get the full 1,000 if the primary home is modest). You would need to verify the exact relative-size rule on your permit path with Planning.

2.      Owner on the property. One of the two dwellings — main house or ADU — needs to be owner-occupied. That was one of the big neighborhood-protection pieces staff added after public input.

3.      Setbacks, height, and the shape of the lot. The ADU has to fit the dimensional standards for your zoning district. Side and rear setbacks, height, and how buildings sit on the lot are why city staff said up front that many lots will be too small for an ADU even though the use is allowed.

4.      Building coverage. Your district sets a maximum building coverage (how much of the lot all buildings together can cover). The ADU’s footprint counts toward that total with the main house and any other structures. It’s not “use half the backyard and call it done.”

5.      HOA / deed restrictions. If a covenant or HOA already bans a second dwelling, city zoning permission doesn’t override that piece of paper.

6.      One ADU mindset. Treat this as one accessory dwelling tied to the main house — not a second free-standing house to sell off the lot.

None of that replaces a site check. Zoning maps, overlays, utilities, and what already sits on the lot all change the answer.

A short example

Imagine a typical in-city house lot where the main house already sits toward the street. For the ADU to work, three things have to line up at once:

·        Setbacks. Pull the side and rear setback lines for your district off the Development Code (or have Planning confirm them). Everything about the ADU — walls, and usually how overhangs are counted — has to stay inside those lines.

·        What’s left after the house. Measure the rear yard that’s still open after you honor those setback lines and leave room for access, drainage, and whatever parking your permit path requires. That leftover rectangle is the real ADU envelope — not the whole backyard.

·        Coverage math. Suppose your district caps building coverage around the middle of the pack (some house-scale districts run in the 50–60% range of the lot for all buildings combined). If the main house, garage, and porch already eat most of that allowance, a detached cottage may not fit even when the setback box looks okay on paper.

So: you don’t “get” a fixed slice of the lot for an ADU. You get whatever footprint still fits inside setbacks + coverage + height + the 1,000 sq ft (and relative-size) cap, with owner occupancy on the property.

Outside city limits the story changes. Unincorporated Greenville County is a different ordinance; towns like Greer or Simpsonville have their own. Same conversation, different book.

What we do before anyone hires an architect

7.      Free site visit and an evaluation on whether an ADU is even in the conversation for that address.

8.      If you already have all that figured out and have plans, we can give you a rough cost range for planning.

9.      Work with local architects when design help is needed (budgeting and options that keep the design intent without blowing the setback box).

10.   Build with the same communication and craftsmanship we use on full custom homes and additions.

Custom home, addition, or ADU?

If you’re unsure which path fits, tell us what you’re trying to solve — privacy for parents, a guest suite, rental help, or a shop with a future living bay. Sometimes an addition is smarter. Sometimes a detached ADU. Sometimes a shop now and a suite later. We’re happy to talk it through.

Next step

If you’re in Greenville or the towns we serve (Simpsonville, Mauldin, Taylors, Greer, Travelers Rest, Piedmont, Fountain Inn, Gray Court, Laurens area), reach out for a free site visit:

·        Web: builtuphomes.com

·        Email: greg@builtuphomes.com

·        Phone: 864-636-9402

— Greg Palmer, Built Up Homes