Home Addition Cost Calculator

How Much Does a Home Addition Cost in Ontario?

A properly built home addition costs $350 to $650+ per square foot of new space. That's the same planning range we use in real budget conversations for home additions and garage builds across South Georgian Bay, and it's what this calculator applies to your inputs.

Additions cost more per square foot than an interior renovation because they carry a full building's worth of work: foundations, structural tie-ins to the existing house, exterior cladding and rooflines matched to the original, and heating, plumbing, and electrical extended into the new space. Putting a kitchen or bathroom in the addition, building up instead of out, or matching a complex roofline all push a project toward the top of the range.

Planning a detached garage or workshop instead? Those typically run $75,000 to $250,000+, depending on size, foundation, electrical service, and whether the space is insulated, heated, or finished above.

Addition Costs Near You

Local conditions move the number. See what drives costs for home additions in Wasaga Beach and home additions in Collingwood, where snow-belt roof loads and escarpment-area foundations tend to push projects toward the upper half of the range. Building a whole new home instead? Try the custom home cost calculator.