Finishing a basement in Ontario

Ceiling height

• At least 2.1 m clear over at least 75% of the finished area (OBC Table 9.5.3.1).
• At least 1.95 m under beams, ducts and bulkheads.
• In a house at least five years old, the existing-house alternative allows 1.95 m over each room (or 2.03 m over half of it).
• Measure before you design: a 50 mm bulkhead under a 2.08 m beam is the difference between passing and not.

Bedrooms

• At least 7 m² (6 m² with built-in cabinets).
• Window glass of at least 5% of the floor area.
• An escape window on any floor with a bedroom: it opens to at least 0.35 m² with no side under 380 mm, without tools, and a window well leaves 550 mm in front of it (OBC 9.9.10.1).
• A sill higher than 1.5 m needs a built-in step below it.

Safety and comfort

• Interconnected smoke alarms on every floor and outside sleeping areas.
• Carbon monoxide alarms near sleeping areas when there's a fuel-burning appliance.
• Insulated outside walls to the energy rules (SB-12), kept off the concrete.
• Heat and fresh air for each finished room; an exhaust fan for any bathroom.
• Access panels for shut-off valves and cleanouts you're about to close in.

When it's more than a basement

A separate apartment is an additional dwelling unit: fire separations, its own exits and zoning approval. Structural changes, underpinning and new or bigger foundation openings need a qualified designer or engineer. DivineDesigner routes those out instead of drawing them.

Questions people ask