How much does it cost to add a second storey loft to a garage in Riverview NB?

Adding a second-storey loft or bonus room above a garage in Riverview, NB typically adds $25,000 to $50,000 on top of the base garage construction cost, bringing the total for a two-car garage with a finished loft to approximately $75,000 to $120,000. The wide range reflects the enormous difference between a basic unfinished storage loft and a fully finished living space with insulation, drywall, flooring, electrical, heating, and plumbing.

The first thing to understand is that a garage with a second storey is a fundamentally different structure than a single-storey garage. The foundation must be designed to carry the additional load — heavier footings, thicker frost walls, and potentially a wider footing than the standard 16-inch minimum. In Riverview, where frost depth reaches 4 to 5 feet below grade, the foundation for a two-storey garage structure costs $10,000 to $18,000 compared to $8,000 to $15,000 for a single-storey garage of the same footprint. The incremental foundation cost of $2,000 to $3,000 is a small price for the structural capacity needed to support a second floor.

The framing for a loft or bonus room above a garage requires a floor system (engineered I-joists or dimensional lumber joists, typically 2x10 or 2x12 at 16 inches on centre), knee walls or full-height walls depending on the roof design, and roof trusses specifically designed for attic use — called attic trusses — that create usable headroom in the centre of the space. Attic trusses cost significantly more than standard trusses: expect $400 to $800 per truss compared to $150 to $300 for standard trusses. For a 24x30 garage, you might need 16 to 20 attic trusses, adding $4,000 to $10,000 to the truss package compared to a single-storey design. The floor joists, subfloor sheathing, and additional wall framing add another $3,000 to $6,000 in materials.

If you want the loft as unfinished storage space only, the additional cost above a single-storey garage is roughly $8,000 to $15,000 — covering the upgraded foundation, attic trusses, floor system, subfloor, and a basic staircase or pull-down ladder. This gives you a dry, accessible storage area without insulation, drywall, or climate control. Many Riverview homeowners choose this approach initially with plans to finish the space later.

A fully finished loft or bonus room adds substantially more. Insulation is critical — the NB climate demands R-32 to R-50 in the ceiling/roof assembly and R-20 or higher in the walls for a heated space above a garage. Spray foam insulation at the roofline is the most effective approach for loft spaces, costing $3,500 to $7,000 for a two-car garage loft. Drywall, taping, and painting add $3,000 to $6,000. Flooring (laminate, vinyl plank, or carpet) runs $1,500 to $4,000. A permanent staircase — required by code for any habitable space — costs $2,000 to $5,000 installed, and takes up roughly 35 to 40 square feet of garage floor space below.

Electrical for a finished loft requires its own circuits — lighting, receptacles, smoke detectors, and potentially a dedicated heating circuit. Budget $2,000 to $4,000 for electrical. If you want the space heated, a ductless mini-split heat pump is the most popular and efficient choice for garage lofts in NB, costing $3,500 to $6,000 installed. It provides both heating and cooling without the complexity of extending the house's ductwork. If you plan to add a bathroom — common for loft spaces used as home offices, guest suites, or rental units — plumbing rough-in and fixtures add $5,000 to $10,000.

Riverview's building department will require a building permit for any garage with a second storey, and the structural design will likely require engineered drawings stamped by a professional engineer, costing $1,000 to $3,000. If the loft will be used as habitable space (not just storage), it must meet additional code requirements including minimum ceiling height (7 feet 6 inches over at least 50 percent of the floor area), egress windows, fire separation from the garage below, and smoke/carbon monoxide detection.

This is a project that requires professional design and construction from the foundation up. The structural, code, and insulation details are too important and too interconnected for a piecemeal approach. Get at least three quotes from contractors experienced with two-storey garage construction. New Brunswick Garages can match you with qualified local builders for free estimates through the New Brunswick Construction Network.