Standard finishes run $50–65 per square foot in 2026; upgraded finishes with a second bedroom and wet bar run $65–85; legal basement apartments run $95–120. A typical 900 sq ft finish lands between $45,000 and $58,500. See the full cost guide for line items.
Lehi requires a building permit for basement finishes, with plan review and standard inspections. For internal apartments, Lehi is the corridor's most affordable city: an application around $25, no impact fee for internal units, one dedicated parking stall, and an owner-occupancy declaration. Parts of the city sit in a sewer-capacity overlay where apartment approvals are restricted — we check your address before design.
In most single-family homes, yes — Utah law requires most cities to allow one internal accessory apartment, subject to city requirements like owner-occupancy, parking, and registration. A Lehi basement apartment renting near $1,400/month against a ~$25 application fee is the best apartment math in Utah County. Details on basement apartments.
About six weeks from demo to final inspection for a standard finish; 8–10 weeks for a full apartment. You get the week-by-week schedule in writing before we start.