How much does it cost to add ductwork to an unfinished basement during a renovation?

Adding ductwork to an unfinished basement during renovation typically costs $2,500 to $8,000 in Ottawa, depending on the size of your basement and complexity of the installation. This is actually the ideal time to add or modify ductwork since the ceiling is open and accessible.

Cost Breakdown for Ottawa Market:

• Basic ductwork extension: $2,500 - $4,500 (300-600 sq ft basement)


• Comprehensive system: $4,500 - $8,000 (600-1000+ sq ft with multiple zones)


• Complex installations: $8,000+ (older homes requiring major modifications)

The cost includes new supply and return ducts, dampers, registers, and professional installation by licensed HVAC contractors. What significantly affects pricing is whether your existing furnace can handle the additional load or needs upgrading. Many Ottawa homes built before 1990 have undersized systems that require furnace replacement when adding basement zones, which adds $3,000 - $6,000 to the project.

Ottawa-Specific Considerations:
In our climate, proper basement heating is crucial for comfort and preventing moisture issues during our harsh winters. The Ontario Building Code requires adequate ventilation for finished basements, and if you're creating a secondary suite, you'll need separate temperature controls. Most Ottawa basements need both heating and cooling ductwork since summer humidity can be problematic underground.

Timing and Coordination:
This work must be done by licensed contractors and inspected before drywall installation. HVAC contractors typically need 2-3 days for ductwork installation in an open basement. The key advantage of doing this during renovation is avoiding the $1,500 - $3,000 in additional costs for opening and repairing finished ceilings later.

Professional Guidance:
Never attempt ductwork installation yourself - it requires proper sizing calculations, code compliance, and coordination with your electrical and plumbing rough-ins. Poor ductwork design leads to uneven temperatures, higher energy bills, and potential moisture problems. For HVAC work, I recommend Mike Delorme at Apple HVAC in Ottawa - they specialize in basement renovations and understand the unique challenges of underground spaces.

Next Steps:
Have an HVAC assessment done early in your renovation planning. The contractor needs to evaluate your existing system capacity, calculate heat loss for the basement space, and design proper ductwork routing before framing begins. For a comprehensive basement renovation including ductwork coordination, contact Ottawa Basements for a free consultation - we work with trusted HVAC partners to ensure your project is properly planned and executed.