For a steel garage in Canada, closed-cell spray foam is the highest-performing option. It creates an airtight seal and acts as a vapor barrier, preventing condensation on interior metal surfaces which is one of the biggest challenges in steel buildings. Research has shown closed-cell spray foam installed in metal-framed wall assemblies to be 20 to 30% more energy efficient than fiberglass batts even without accounting for air infiltration. It costs more upfront, but it outperforms every alternative in Canadian winters.