How to 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
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
Step 1: Calculate Duct Sizes
Use Manual D calculations to determine duct diameter for each room based on CFM requirements. Undersized ducts reduce efficiency.
2 Step 2: Plan Duct Routes
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
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.
3 Step 3: Install Main Trunk Lines
Mike Johnson: "Pro tip: Make sure to double-check this before moving to the next step..."
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.
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.
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.
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.