Detached ADU rules in Utah County, city by city

Orem prohibited detached accessory dwelling units before SB 284, so this is a genuine change rather than an adjustment. The city took a detached-ADU update to a council work session on July 14, 2026 and to a planning commission hearing the following day. As proposed, Orem would keep detached units out of the front yard and prohibit renting them short term. We could not verify an adopted ordinance, so treat the details as likely-but-not-final and confirm before you plan around them.

We could not confirm a current Vineyard ordinance permitting detached accessory dwelling units, or a published proposal. There's a practical reason it may matter less here than elsewhere: SB 284's requirement only reaches lots of 11,000 square feet or more, and Vineyard is a recently built city of comparatively small lots. Plenty of Vineyard homes won't clear that threshold no matter what the city adopts — which makes the basement unit the realistic path here rather than the fallback.

We could not confirm an adopted Lindon ordinance permitting detached accessory dwelling units, or a published proposal. Lindon's code was current through an ordinance passed June 15, 2026, which is before most cities took up their SB 284 rewrites. Lindon lots run unusually large for this valley, so a high share of them are likely to clear the 11,000 square foot threshold — meaning the rewrite, whenever it lands, probably changes more here than in most of the corridor.

Pleasant Grove was ahead of this. City code already allows an accessory apartment in a detached accessory structure, alongside the basement, over-garage and addition options, in the A-1, R-R, R-1, RM-7, DV and Grove mixed housing zones. What SB 284 changes for Pleasant Grove is narrower than for its neighbors, but the zone list still means the answer depends on your parcel.

American Fork has been approving detached accessory dwelling units case by case through conditional use permits, with one granted in December 2025. That's the exact mechanism SB 284 takes away: for a lot of 11,000 square feet or more, a city can no longer require a conditional use permit. So American Fork's process has to change by October 1, 2026, and we could not verify the replacement ordinance. If you were told no here before, the answer may now be different.

Cedar Hills permits accessory dwelling units in all residential zones unless the code prohibits them somewhere specific, but we could not confirm an ordinance addressing detached units under SB 284. Worth asking the city directly, because the general permission and the detached question are not the same question.

Highland's existing rules do not permit an accessory dwelling unit in a detached accessory building. That position cannot survive October 1 for qualifying lots, and the city has been working on it — planning commissioners discussed ADUs on March 31, 2026 and agreed they shouldn't be permitted on lots under 11,000 square feet, which lines up exactly with the state floor. We could not verify a final adopted ordinance.

The part that catches people

Whether your Highland lot clears 11,000 square feet is the whole question, and it isn't a matter of opinion — it's on the county parcel record. We look it up before anything else, because it determines which conversation we're even having.

We looked and could not confirm an adopted or published detached-ADU ordinance for Alpine, and we'd rather say that than guess. Alpine lots are large, so a high share of them are likely to clear the 11,000 square foot threshold — which makes Alpine one of the places where the October 1 deadline could change the most. We're re-checking this one, and it's worth a direct call to the city in the meantime.

The part that catches people

Alpine's foothill lots come with steeper grades and occasional geotechnical review, which affects a detached structure considerably more than it affects a basement. If both options are open to you here, the cost gap between them is usually wider in Alpine than elsewhere in the corridor.

Lehi has already done this. The city approved its implementing ordinance in July 2026, and the change is large: the detached lot minimum was 14,520 square feet and is now the state's 11,000. A detached unit needs a six-foot setback, has to be smaller than the main house, and has a 300 square foot floor. Parking is two stalls for a unit of 650 square feet or more, one below that. The city's own estimate was that eligible properties would increase by more than 20% — so if you were told no in Lehi before, ask again.