How much does it cost to install spiral ductwork versus rectangular ducts in Toronto?

Spiral ductwork costs $10 to $25 per linear foot installed in the GTA, while rectangular ductwork runs $12 to $30 per linear foot — but the real cost comparison is more nuanced than these per-foot numbers suggest because the two types serve different purposes and each has distinct advantages that affect overall project cost.

Spiral round duct is factory-manufactured with a continuous spiral seam that creates a stronger, more airtight product than standard snap-lock round duct. The spiral seam means fewer leak points, which translates to better energy efficiency over the life of the system. From an airflow perspective, round duct is the most efficient shape — air encounters less friction moving through a round profile than through a rectangular one of equivalent capacity. This means you can often use a slightly smaller diameter spiral duct to deliver the same airflow as a larger rectangular duct, which can reduce material costs on some projects.

Spiral duct has become increasingly popular in GTA basement renovations and loft-style living spaces where the ductwork will be left exposed. The clean, industrial aesthetic of exposed spiral duct painted to match the ceiling eliminates the need for soffits and bulkheads, which actually saves money on framing, drywall, taping, and painting. In a typical Toronto basement renovation where a rectangular trunk line would require a $1,500 to $3,000 bulkhead to conceal it, exposed spiral duct can deliver a net cost savings despite the slightly higher duct material price.

Rectangular duct costs more per linear foot primarily because of fabrication time — most rectangular fittings are custom-built in the contractor's sheet metal shop, while spiral duct and round fittings are factory-produced in standard sizes. However, rectangular duct's key advantage is its lower profile. A 20x8 inch rectangular trunk delivers similar airflow to a 14 inch round duct but takes only 8 inches of vertical space versus 14 inches. In GTA homes with low basement ceilings — common in post-war bungalows across Scarborough, Etobicoke, and North York — that 6-inch difference in headroom can determine whether a basement is comfortable to stand in or not.

For a complete duct system comparison in a typical 2,000 square foot GTA home, a system using primarily spiral round duct might cost $6,000 to $12,000, while an equivalent system using rectangular trunk lines with round branches might run $7,000 to $14,000. The rectangular system costs more in fabrication and labour but may be necessary where ceiling height is limited.

The best approach for most Toronto homes is a hybrid — rectangular trunk lines where headroom is critical, with round or spiral branch runs to individual rooms. This is what most experienced GTA ductwork contractors recommend and install. When getting quotes, ask whether the contractor uses spiral or snap-lock round duct for branches, and insist on mastic sealing at every joint regardless of duct type.

Get matched with experienced ductwork contractors through Toronto Ductwork and the Toronto Construction Network for free estimates on your project.