Leaking or disconnected ductwork — San Jose, California

Leaking ductwork is one of the most under-diagnosed home comfort problems. The average home loses 20–30% of conditioned air through duct leaks, gaps, and poor connections — essentially paying to heat or cool your attic, crawlspace, or walls instead of your living space. Symptoms include rooms that are always too hot or too cold despite the HVAC running, excessive dust throughout the house (ducts pull in attic or crawlspace air through leaks), higher-than-expected energy bills, and the HVAC system running longer cycles to reach the thermostat setting. Common leak points are joints where duct sections connect (especially flex duct to rigid metal), boot connections where ducts meet floor or ceiling registers, return-air plenums, and anywhere duct tape (which dries out and fails within 2–5 years) was used instead of mastic sealant. An HVAC technician can perform a duct blaster test to measure total leakage, then seal joints with mastic or metallic tape and insulate exposed duct runs. Sealing costs $500–$2,000 for a typical home and often reduces energy bills by 15–25%, paying for itself within 1–3 years.