ADUs and Land Use in the Black Hills: Zoning by County, Plus Covenants vs. HOAs

A question I get almost every week from acreage buyers and empty nesters alike: "Can I put a small second home on this lot for my parents, or as a rental, or just as a home office with a bathroom?" The honest answer in the Black Hills is always the same: it depends entirely on which side of a county line, or a city limit, the parcel sits on. Zoning here is not one system. It is five or six different systems layered across the same mountain range, and the rules that apply to a lot in Rapid City can be nearly opposite the rules that apply to a lot twenty minutes away in unincorporated Custer County.

This is my attempt to lay out, plainly, what an accessory dwelling unit is, how each of the jurisdictions I work in treats them, and the separate but related question I get almost as often: what is the actual difference between a covenant and an HOA. Both questions come up constantly with buyers who are used to one set of rules somewhere else and assume it travels with them. It usually does not.

Before anything else, the disclaimer that belongs at the top of an article like this rather than buried at the bottom: I am not a land use attorney, a zoning administrator, or a code official. Zoning ordinances change, planning commissions amend them, and the summaries below are general information based on my own reading of published county and city code as of this writing. Before you buy a lot, place a second structure, or count on being able to build anything specific, confirm current requirements in writing with the planning and zoning office that has jurisdiction over that parcel. A phone call is a start. A written answer with the parcel number on it is what belongs in your file.

What an ADU is, and two phrases worth knowing

An accessory dwelling unit, usually shortened to ADU, is a secondary living space on a lot that already has a primary home. It can be attached (a suite above a garage, a finished basement apartment with its own entrance) or detached (a small standalone cottage or converted outbuilding). What makes it an ADU rather than just extra square footage is that it has its own kitchen or kitchenette, its own bathroom, and functions as an independent living unit, even if a family member never pays rent on it.

Two zoning phrases are worth knowing because they change everything about whether a plan is realistic. A permitted use is something you are allowed to do as of right, as long as you meet the written standards, no public hearing required. A conditional use, sometimes called a special exception, means the use is possible but requires an application, a public hearing, and a planning commission's approval, which can be granted, denied, or granted with conditions. The difference between those two categories is often the difference between a project that takes a few weeks to permit and one that takes a few months and is not guaranteed.

South Dakota has no statewide ADU law. There is no single answer that applies from Rapid City to Nemo to Sturgis. Each city and county writes and amends its own rules, and that is exactly why this article is organized jurisdiction by jurisdiction rather than as one set of answers.

City of Rapid City

Rapid City has one of the more clearly written ADU ordinances in the region, and it treats ADUs as a permitted use, not a conditional one, in Low Density Residential-1, Low Density Residential-2, Medium Density Residential, High Density Residential, and General Agricultural districts, provided the requirements are met. In the Park Forest district, an ADU is allowed only as part of a single-family dwelling rather than as a detached structure.

The city requires owner-occupancy: the property owner has to live full time in either the main home or the accessory unit, not rent both units out to tenants while living elsewhere. Only one ADU is allowed per property. A detached ADU has to be smaller than the primary home's footprint and cannot exceed ten percent of the lot area, and lots under 6,500 square feet are limited to an ADU built within the main structure rather than a detached building. Parking adds up fast: the code calls for two off-street spaces for the main home and one more for the accessory unit, three total. And rather than a full building permit hearing, the city runs ADUs through a registration process with the Department of Community Development, which reviews a site plan, floor plan, and code compliance documentation before approving.

If you are inside Rapid City limits and thinking about a mother-in-law suite, a rental unit, or a place for adult kids, this is genuinely one of the more workable jurisdictions in the region for it. Confirm your specific lot's zoning district and current requirements with the city's Community Planning and Development office before you design anything, since ordinances do get amended.

Unincorporated Pennington County

Outside Rapid City's limits but still in Pennington County, the county's own zoning ordinance separately addresses guest houses and accessory dwellings, and it treats them as accessory uses that must remain clearly subordinate to the main home on the lot, generally allowing only one principal structure and its accessory buildings per parcel. Depending on the district and the specific use, a conditional use permit can be required, which means a hearing in front of the planning commission rather than an automatic approval. The county also separately regulates vacation home rentals as their own category, distinct from an ADU used by family or long-term tenants, so a plan to combine a second unit with short-term rental income is worth running past the planning office as two separate questions, not one.

Pennington County is generally regarded as one of the more workable counties in the region for a properly permitted ADU or guest house, but "workable" here means "a defined process exists," not "automatic." Get the specific section of the ordinance that applies to your district and confirm whether your plan needs a conditional use permit before you assume a timeline.

Meade County

Meade County's published materials focus on building permits, setbacks, and site plan review through the Equalization and Planning office, rather than a detailed, named ADU category the way Rapid City's ordinance does. Structures below certain size thresholds, small accessory buildings and small decks among them, may not need a building permit at all, but that is a permit threshold question, not a green light to add a second dwelling. Large portions of unincorporated Meade County have historically had lighter zoning than incorporated areas, which cuts both ways: fewer hoops in some respects, but also fewer clearly written protections and standards to rely on. If you are looking at land in Meade County with a second dwelling in mind, this is a jurisdiction where I would get a direct, written answer from the county planning office for the specific parcel rather than assuming anything based on what a neighboring lot has on it.

Custer County

Custer County is genuinely two different rulebooks depending on whether a parcel sits inside the City of Custer or out in the unincorporated county. Inside city limits, Custer has its own specific accessory dwelling unit provisions allowing one ADU per property where permitted, with its own standards for things like height and parking. Outside city limits, unincorporated Custer County has historically had little to no comprehensive countywide zoning or building code, which means a second dwelling out in the county is often more a matter of what your specific covenants allow than what the county's zoning restricts. That sounds like more freedom, and in some ways it is, but it also means fewer built-in protections if a future owner or a neighboring property does something you would rather they hadn't.

If you are drawn to Custer County for the land, my guide to buying acreage in the Black Hills covers the other due diligence items that matter as much as zoning does, wells, septic, and legal road access chief among them, and my Custer community guide covers the town itself.

Lawrence County

Lawrence County adopted a countywide zoning ordinance, but coverage and specifics vary by district and by whether a parcel is inside a municipality like Deadwood, Lead, or Spearfish versus out in the unincorporated county. A number of unincorporated pockets in Lawrence County, Powder House Pass being one example near Lead and Deadwood, are governed day to day less by county zoning and more by private subdivision covenants and, in some cases, Community Improvement District rules. That is an important distinction if you are picturing a guest cabin or a workshop apartment: the deciding document might be sitting in your title work rather than in the county code.

Covenants and HOAs are not the same thing, and this trips up a lot of buyers

This is the second half of what I get asked about constantly, and it deserves its own clear explanation rather than a footnote.

A covenant, often written out as CC&Rs (covenants, conditions, and restrictions), is a set of private restrictions recorded against the land itself, typically when a subdivision was originally platted. Covenants run with the land, meaning they apply to whoever owns the property, not just the original buyer, and they show up in the title work on every future sale. A covenant might restrict lot coverage, require a minimum home size, limit outbuildings, restrict fencing materials, or say something specific about accessory structures, all independent of what the county or city zoning code allows.

An HOA, a homeowners association, is a different thing: a legal entity, usually incorporated, that collects dues, holds a board, and actively enforces rules, often while also managing shared amenities like private roads, a community well, common green space, or a clubhouse. An HOA typically enforces a set of covenants, but the two are not interchangeable, and this is the part that catches people. Plenty of subdivisions across the Black Hills have recorded covenants without any active homeowners association standing behind them. In that situation, the restrictions still exist and still bind you as the owner, but there is no association board, no dues, and often a much less consistent track record of active enforcement, because enforcement in that scenario usually falls to individual neighbors rather than a managing entity.

What that means practically: a subdivision can privately prohibit something a city or county would otherwise allow, and an ADU that is a permitted use under city or county zoning can still be off the table because of a covenant that predates that zoning entirely. Before you count on building a second structure, read the actual recorded covenants for the specific subdivision, not just a real estate agent's summary of them, and separately find out whether an active HOA exists to enforce them or whether they sit unmanaged on the title. Both pieces come through in title work, and I make sure my clients read them rather than skim them.

How I handle this on a transaction

When an ADU, guest house, or any secondary structure is part of why a buyer wants a particular property, I treat the zoning and covenant research as part of the transaction rather than homework I hand off. That means identifying exactly which jurisdiction governs the parcel, city or unincorporated county, and which zoning district within it. It means getting a written answer, not a verbal one, from the planning office about whether the specific use is permitted, conditional, or not addressed at all. It means pulling the recorded covenants and confirming whether an HOA actively enforces them. And it means building enough time into the inspection and due diligence period that you can still walk away if an answer comes back different than expected, rather than finding out after closing that the plan you bought the property for is not available to you.

None of this should scare anyone off from building or buying with a second unit in mind. It is simply the homework, and every county here handles it differently enough that the homework genuinely matters. If you are weighing a lot with an ADU or guest house in mind anywhere in the Black Hills, I would rather spend the time confirming what is allowed before you write an offer than help you find that out the hard way afterward.

If you are exploring rural land more broadly, my buying acreage guide covers wells, septic, and road access, and my wells and water systems guide and septic systems guide go deep on the infrastructure side. My community guides for Hill City, Custer, Piedmont, and Hot Springs cover the towns where I answer these zoning and covenant questions most often, and my free buyer's guide rounds up the due diligence items that matter most before you write an offer on rural or acreage property.

This article is general information based on published city and county code as of this writing, not legal advice. Zoning ordinances, permitted use tables, and covenant enforcement all vary by jurisdiction and change over time. Before buying land or planning a second structure, confirm current requirements in writing with the specific city or county planning and zoning office, and have an attorney review any recorded covenants that matter to your plans.