Seal Flex Duct Connections With Fire Block Spray Foam?
AtticAdventures
| Posted in Energy Efficiency and Durability on
Is it acceptable to seal flex duct connections (at supply plenum, ceiling boot, where main supply lines branch into multiple lines) using a can of fire blocking spray foam? Thank You.
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Replies
Randy,
It's acceptable, but canned spray foam may not provide a dependable and durable air seal. Either high-quality foil HVAC tape or mastic is usually a better choice for air sealing duct seams.
If you do end up using spray foam, a thicker layer will provide a better air seal than a thin layer.