Duct leakage testing — $300. Testing ducts is now a requirement in Metro Denver for all ducts that have runs through unconditioned spaces such as attics and crawlspaces. In order to pass the test, ducts can not have more then 4% leakage of total sq footage. For example, a 2000 sq foot home is allowed 80 CFM (cubic feet per minute) of air leakage per the 2015 IRC Energy Code.
In order to pass the test, it is important to apply rigorous air sealing measures using duct mastic and aluminum foil tapes on all joints, branches, elbows etc. During the test, a blower fan will pressurize the duct system and a total air leakage number will be displayed. A duct leakage test can be performed at rough-in before drywall is hung, or at post-construction. Performing the test during rough-in is highly recommended so any problem areas can be addressed.