Cost to Build a Detached Garage: Full Breakdown for a 40x60 Metal Garage

If you're pricing out a large detached garage, you've probably noticed that most cost guides give you a vague range like "$19,000 to $75,000" and call it a day. That's not useful when you're trying to budget a real project. This guide walks through every cost category for a fully functional detached garage, using the Boss Buildings 40'x60'x12' All Vertical Metal Garage as our reference structure. At 2,400 square feet, it's a serious build, large enough for multiple vehicles, heavy equipment, a workshop, or any combination of those. We'll cover the structure itself, the concrete slab, insulation, electrical, doors, permits, and the extras that tend to catch people off guard. For a fully finished, functional 40x60 detached metal garage, expect to spend between $80,000 and $110,000+ all-in, depending on your location, site conditions, and finish level. The structure itself is only part of the cost. Below, we'll break down: The prefab metal building (structure cost) Concrete slab foundation Insulation Electrical and lighting Doors and windows (what's included vs. what's extra) Permits and site prep Optional upgrades (HVAC, plumbing, interior finishing) Total cost summary The Structure: What the 40x60 Metal Garage Costs The Boss Buildings 40'x60'x12' All Vertical Metal Garage starts at around $48,095. That price includes delivery and installation, which matters more than most people realize. A lot of prefab competitors quote the kit price and leave you to figure out freight and labor separately, which can add $5,000 to $15,000 to the bill. What's included in the structure price This building comes fully enclosed with vertical-panel steel siding, a 14-gauge steel tube frame (2.5" x 2.5"), and a two-tone finish. The standard package includes: 1 roll-up door (10' x 10') 4 roll-up doors (10' x 8') 2 walk-in doors (36" x 80") 4 windows (30" x 36") Delivery and installation by a Boss Buildings crew The all-vertical roof design is worth calling out specifically. Vertical panels run top to bottom rather than horizontally, which means water and debris shed off cleanly instead of sitting in the seams. For a 2,400 sq ft building that's meant to last decades, that's the right call. Metal vs. wood: why metal wins at this size At 40x60, traditional stick-built construction runs $35 to $65 per square foot for framing alone, before any finishes. That puts a comparable wood-framed detached garage at $84,000 to $156,000 for the structure, not counting the foundation. A prefab metal building at this scale delivers comparable (often superior) structural integrity at a fraction of that cost. The structure cost for this build: Around $48,095 (delivery and installation included) Concrete Slab Foundation The building is one line item. The slab is another, and for a 40x60 footprint, it's a significant one. A 40x60 slab covers 2,400 square feet. At the current national average of $6 to $12 per square foot installed, you're looking at: Slab Scenario Cost Estimate Basic slab, $6