Most single-family zones allow one main house per lot, so a second home usually needs an accessory dwelling unit allowance, a zone that permits more than one dwelling, or a lot split into separate parcels. Which route works depends on the zone's minimum lot size and whether each house must be sold on its own.
New to zoning types? Read what residential zoning means and what it allows.
R - Residential
Is multiple houses allowed in Columbus?
Open the Columbus zoning map to find a property's zoning district, then check what that district allows.
Check zoning in Columbus, OH →There are four common routes, and the right one depends on the residential zone and on whether each house needs to be sold on its own.
| Route | How it works | Can the houses be sold separately? |
|---|---|---|
| Accessory dwelling unit | A smaller second home on the same lot, allowed in many single-family zones | Usually no |
| Zone that allows multiple dwellings | Two-family or multi-family zones may allow detached homes on one lot | Usually no, unless converted to condominiums |
| Lot split or subdivision | Divide the land into legal lots, one house on each | Yes |
| Cluster or planned development | Homes grouped on part of a larger site with shared open land | Usually yes |
For a single extra home, an accessory dwelling unit is often the simplest path. Many codes cap its size and some limit renting it, so read those rules before you design.
It depends on the zone's minimum lot size and how you add the second house. To split a lot, each new lot usually has to meet the full minimum lot area, width and street frontage on its own. A lot needs roughly twice the minimum lot area, plus room for access, to be split once.
An ADU or a second dwelling allowed on one lot is different. The lot doesn't have to double, but both houses must fit within the setbacks and lot coverage cap. The lot coverage calculator and setback calculator show how much room is left. Some states have loosened lot split rules. California's Senate Bill 9, for instance, lets cities approve two units and in some cases up to four on single-family lots, as described in Wikipedia's summary of single-family zoning reforms.
Listings for compounds, family land and homesteads with two or more homes are common, but the second house isn't always legal. Before you buy, confirm these points with the planning department and county records:
A detached second house approved only as a guest house may not be allowed to have a full kitchen or rent to tenants.
On larger land, codes may allow residential cluster development, which groups homes on part of the site and keeps the rest as open space, farmland or recreation land. A planned unit development works in a similar way, with site-specific rules approved by the planning commission. Both take longer than a simple lot split and usually involve a public hearing.
Each home needs water, sewer or septic, and power. A well or septic system sized for one home may not be approved for two. Fire codes often set driveway width and length limits when homes sit far from the street, and a shared driveway may need a recorded access agreement.
If two attached units would work, compare the rules for a duplex.
In most single-family zones, one main house plus, where allowed, one or two accessory units. Zones that allow multi-family or planned developments can allow more, based on the density limit for the district.
Usually, if the second house is a legal dwelling such as an approved ADU. Some codes also allow a temporary dwelling, often a manufactured home, for an ill or elderly relative with a special permit that ends when the need ends.
Not always. A house with an ADU is usually still treated as single-family. Two full primary homes on one lot may be classified as a two-family or multi-family use, depending on the code.
Sometimes, if it meets the code's ADU rules and sits on a foundation. Tiny homes on wheels are often treated as RVs, which most residential zones don't allow as full-time housing. See our tiny home zoning guide.