Check your ducts for air leaks. First, look for sections that should be joined but have separated and then look for obvious holes.
If you use tape to seal your ducts, avoid cloth-backed, rubber adhesive duct tape -- it tends to fail quickly. Instead, use mastic, butyl tape, foil tape, or other heat-approved tapes. Look for tape with the Underwriters Laboratories (UL) logo.
Hire a professional to install both supply and return registers in the basement rooms after converting your basement to a living area.
Be sure a well-sealed vapor barrier exists on the outside of the insulation on cooling ducts to prevent moisture condensation.
Be sure to get professional help when doing duct work. A qualified professional should always perform changes and repairs to a duct system. Give us a call: 239-596-5855.