About Outbuildings Calculations
An outbuilding like a garage is one of the more predictable structures to budget, because it's mostly a simple box: a slab, walls, a roof, a door or two, and whatever finish you choose. That makes a square-foot cost estimate more reliable here than for a complex remodel, though it's still a planning number, not a quote.
Size and finish level are the two big levers. A bare detached garage, a slab and an unfinished shell, sits at the low end of the per-square-foot range. Add insulation, drywall, electrical, heat, plumbing, or living space above, and the cost climbs fast. Decide what you actually need the building to do before you price it.
The site matters too. A flat, accessible lot with utilities nearby is cheap to build on; a sloped site, poor soil, a long utility run, or tight access all add cost a per-square-foot number won't capture. So does whether the structure is attached, which shares a wall and can be cheaper, or fully detached with its own four walls and roof.
Use the cost tool to set a realistic budget range, then get a few local quotes to dial it in. Building costs swing by region and by year, and permits, foundation work, and finishes are where surprises hide. Run the estimate first so you know whether the project fits before you pay for plans.