The average cost to replace ductwork is $1,400 to $5,600, depending on the house size. Air duct installation costs $25 to $55 per linear foot or $270 to $500 per duct. HVAC ductwork repair costs $200 to $700 for minor leaks.

Ductwork lasts 10 to 20 years on average before it needs replacing. Most ducts need work when replacing HVAC systems more than 15 years old or when upgrading to bigger or higher-efficiency units.

Signs to repair or replace ductwork:

• Unbalanced heating or cooling
• Rising energy bills
• Reduced airflow
• Noisy HVAC system with vibrating ducts
• Consistently dusty home
• Mold, odors, or moisture damage in air ducts
• Pest infestations in the ductwork
• Collapsed, loosened, torn, or rusted duct sections

Replacing ductwork takes 1 to 2 days on average or up to 4 days for larger homes or complex projects. Installation time depends on the home's size, age, number of HVAC units, duct type, and crew size. Allow more time when wall or ceiling repairs are necessary.

Ductwork is a large piping system that sends heated or cooled air from HVAC units throughout the home. Duct vents are long tubes or rectangular sheet-metal channels made of fiberglass, steel, PVC, or aluminum. These rigid or flexible ducts are in ceilings, attics, basements, and crawl spaces.

There are three main types of ductwork:

• Flexible – Round tubes with steel wire reinforcement and covered with plastic or aluminum. Lightweight and easy to install but shortest lifespan. Prone to tears, pest infestations, and moisture damage.
• Fiberglass / fiberboard – Insulated by fiberglass to prevent condensation and muffle the HVAC system sound. Fiberglass can deteriorate and release fibers into the air over time, causing health issues.
• Sheet metal – Rigid in shape, made from galvanized steel or aluminum, lightweight, easy to install, and mold-resistant.

You should replace ductwork when replacing an AC unit if the ducts are moldy, more than 20 years old, or cracked. AC upgrades often require new ductwork to fit bigger systems properly. HVAC installers inspect ducts first and recommend cleaning, repairing, or replacing ducts as needed.

DIY ductwork replacement is illegal in most states without a license. Hire certified HVAC contractors for duct installation and repairs.

Start by searching our list of ductwork companies, then compare reviews and costs. After finding and contacting services:

• Make sure they are licensed, bonded, and insured.
• Seek out contractors with at least 2 to 5 years of work experience.
• Collect project bids from three different companies to compare estimates.
• Avoid choosing the lowest estimates that lead to low-quality work.
• Compare past reviews on HomeGuide and Google.
• Don’t sign contracts until you understand the total project cost.
• Make a payment schedule instead of paying in full upfront to avoid scams.

Ask to see their certifications from:

• Air Conditioning Contractors of America (ACCA)
• American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE)
• North American Technician Excellence (NATE)

After asking questions and verifying their credentials, hire the best ductwork installation contractors in your area.

When hiring a duct installer, ask them the following questions:

• Which duct type is best for my home?
• How many duct installations have you done?
• Can I see photos of your past work?
• Can you provide references from previous ductwork projects?
• What does your labor warranty cover?
• If installing flex ducts, will you add supports every 4 feet?
• Can you install ducts in air-conditioned areas to reduce energy losses?
• Will you insulate the entire length of all supply lines?
• Do you use rigid connectors and sealant on flex-duct connections?
• Will you test for duct leaks after installation?
• Do you use Manual D duct-design calculation software to size the ducts?
• Can you also make Manual J and Manual T calculations to check the supply-register sizes?
• Do your prices include a home energy audit to prevent leaks and optimize airflow?
• Will you pull permits for this duct installation, and how much do they cost?
• Does this estimate include all labor, materials, and cleanup costs?
• How long will this duct installation take?