The average US home is said to have greater than 15% duct leakage to the outside. That’s money going right out window. Sometimes there are cheap fixes. The fix pictured below cut more than 50 CFM (that’s cubic feet per minute) of leakage from a new home. We removed the grille from the HVAC supply register and sealed the metal boot to the surrounding drywall – for just 4 registers. We used mastic. Painters’ caulk works fine too. The grille will cover the grey mastic.
before after
