Basement Apartments in Utah County

Millgate Homes builds basement apartments in Utah County for two very different kinds of homeowners: people who want rental income from a basement they’re not using, and people who want a real, self-contained space for a parent, adult child, or other family member. Both start the same way — a legal basement apartment needs a bedroom with an egress window, a bathroom, some form of kitchen or kitchenette, and usually a separate entrance — but which city you’re in changes the permitting path more than almost any other basement project we build.

As of 2025, Utah state law (HB 82, now Utah Code § 10-9a-530) requires cities to allow an internal basement apartment as a permitted use in most residential zones — meaning a qualifying basement apartment generally doesn’t need a discretionary public hearing the way it once might have. Cities still set their own rules on owner-occupancy, parking, and registration, though, and those rules genuinely differ across American Fork, Lehi, Saratoga Springs, and Eagle Mountain:

• Lehi requires the homeowner to occupy the primary home, with a recorded Declaration of Owner Occupancy filed with Utah County, one dedicated off-street parking space, a minimum 6,000-square-foot lot, and only one ADU per parcel.
• Saratoga Springs zones every property as IADU Approved, Potential, or Prohibited — in a Potential or Prohibited zone, the surrounding subdivision has to petition the city for reclassification before an apartment can be permitted at all. Approved properties need a building permit plus a separate IADU registration form, a dedicated 9’x18’ paved parking space, and owner-occupancy of either unit.
• Eagle Mountain requires two off-street parking spaces (more than most Utah County cities ask for), a 36-inch-wide unobstructed path from the apartment’s exit to the street, and restricts ADUs to true single-family homes — not townhomes or multi-family properties. Eagle Mountain’s growth from roughly 250 residents to more than 76,000 in three decades means a lot of newer single-family homes are exactly the kind of property this applies to.
• American Fork’s basement/accessory apartment rules are on file with the city’s building department — we’ll confirm the current owner-occupancy and parking requirements with them directly as part of your free consultation, since we want you working from the current version, not an assumption.

None of that is legal advice, and city ordinances change — Millgate pulls the building permit and handles every construction inspection, and we’ll walk you through what your specific city requires before you commit to a design, but the owner-occupancy declaration or IADU registration paperwork itself is typically something you file with the city directly.