If you’re replacing ductwork or adding a new run, you’ll likely hear two options: flexible duct and sheet metal. Both can work well in a South Florida home. The right choice depends on your attic, your budget, and how the system is laid out. Here’s how they compare.
Flexible Duct
Flex duct is a round, flexible tube with a wire coil, wrapped in insulation and an outer vapor barrier. It’s the most common ductwork in Florida homes built in the last few decades.
- Lower cost. The material is less expensive and it installs faster, which keeps labor down.
- Insulation is built in. It comes pre-insulated, commonly R-6 or R-8, which matters in attics that get extremely hot.
- Easy to route. It bends around trusses and obstacles in tight attic spaces.
- Installation quality matters most. Flex duct performs well only when it’s pulled tight, supported properly, and run without sharp bends. Sagging, kinked, or overly long runs restrict airflow badly.
- Easier to damage. It can be crushed by foot traffic or stored items, and the outer jacket can tear.
Sheet Metal Ductwork
Metal ducts are rigid, usually galvanized steel, and come in round or rectangular sections joined together and sealed.
- Durable. Metal holds its shape for decades and resists crushing and pests.
- Smooth inside. Air moves through with less resistance, and the surface is easier to clean.
- Higher cost. Materials and labor cost more, and installation takes longer.
- Must be insulated and sealed well. In a humid attic, uninsulated or poorly wrapped metal duct can sweat, dripping water onto ceilings and inviting mold.
Which One Is Right for You?
For most South Florida homes, a well-designed system that uses both works best: a metal plenum and main trunk near the air handler, with properly installed flex duct running to each room. That combines durability where airflow is highest with flexibility where the runs get tight.
Whichever material you choose, three things matter more than the material itself:
- Correct sizing for your home and your AC system
- Tight, sealed connections with mastic or rated foil tape
- Short, straight, well-supported runs with no crushed or kinked sections
A poorly installed metal system can perform worse than a well-installed flex system, and the reverse is true too.
When It’s Time to Replace
If your flex duct is sagging, torn, or flattened, or your metal ducts are rusted or sweating, it may be time for new ductwork. Learn how we handle air duct replacement, what replacement typically costs in South Florida, and the signs your ducts need repair.
Talk to South Florida Ducts About Your Ductwork
Family-owned and serving Broward, Miami-Dade, and Palm Beach counties. Call (954) 909-4281 or request a free quote and we’ll take a look. No pressure, no upsell.