8 Types of HVAC Ductwork for Homes

Eight common ductwork types, each with trade-offs:

• Sheet metal - durable, good airflow, pricier install
• Flex duct - cheap and easy, but kinks, sags, and crushes
• Fiberglass-lined - quiet, but traps dust and degrades when damp
• Fiberboard - affordable, moisture-prone, common in older homes
• Spiral / rigid round - excellent airflow, great for trunk lines
• Rectangular trunk - space-efficient, more airflow resistance
• Ductless mini-split - zoned, no ducts needed

Many older Pacific Northwest homes have undersized ducts sized for outdated furnaces. Replace ducts when they're 20-30+ years old, leaking, or when upgrading to a high-efficiency heat pump. Warning signs: hot and cold spots, weak airflow, rising bills, excess dust, and rattling or whistling vents.