How to Install Ductwork
Proper ductwork installation ensures efficient HVAC performance and even temperature throughout your home. Learn duct sizing, routing, sealing, and insulation techniques.
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0 of 6 steps completedStep-by-Step Instructions
1 Step 1: Calculate Duct Sizes
Step 1: Calculate Duct Sizes
Use Manual D calculations to determine duct diameter for each room based on CFM requirements. Undersized ducts reduce efficiency.
Laser Distance Measure
Digital laser for measuring duct runs
2 Step 2: Plan Duct Routes
Step 2: Plan Duct Routes
Route ducts through conditioned space when possible. Minimize turns, and use gradual bends instead of sharp elbows to reduce resistance.
Sheet Metal Snips
Aviation snips for cutting ductwork
3 Step 3: Install Main Trunk Lines
Step 3: Install Main Trunk Lines
Hang main trunk ducts from ceiling joists using metal straps. Maintain 1/4 inch slope per foot toward the air handler for drainage.
HVAC Duct Tape
Foil-backed tape rated for ductwork
4 Step 4: Attach Branch Ducts
Step 4: Attach Branch Ducts
Connect branch ducts to trunk using properly sized take-offs. Ensure smooth transitions without crimping that restricts airflow.
Duct Insulation
R-6 flexible duct wrap insulation
5 Step 5: Seal All Joints
Step 5: Seal All Joints
Apply mastic sealant or metal tape to all seams and connections. Duct tape deteriorates and isn't suitable for HVAC ductwork.
Duct Sealant Mastic
Water-based mastic for sealing duct joints
6 Step 6: Insulate Ducts in Unconditioned Spaces
Step 6: Insulate Ducts in Unconditioned Spaces
Wrap ducts in attics, crawlspaces, and garages with R-6 or higher insulation. Secure with wire or zip ties and seal vapor barrier seams.
Duct Supports
Metal strap hangers for suspending ductwork