§110.7 · Air-leakage testing (envelope and ducts)

# §110.7: Air-leakage testing

What it requires

Two separate tests, both run by a CHEERS-registered ECC Rater (or equivalent field-verification credential):

• Envelope blower-door test. Required on newly constructed single-family homes, the building has to hit a measured air-leakage limit (typically 5 ACH50 by default, lower in some climate zones).
• Duct leakage test. Required when ducts are installed or substantially replaced. Two flavors: total leakage at 25 Pa, and leakage to outside at 25 Pa. The CF1R specifies which test applies based on duct location (attic, conditioned space, mixed).

When it applies

• Newly constructed dwellings, both envelope and duct tests.
• Additions over 700 ft², duct test on the new ducts.
• HVAC alterations where ≥40 linear feet of duct is replaced, duct test on the altered ducts.

How we use it

The CF1R lists every required §110.7 test on the project's measure summary, and the test results land on a separate CF3R Installation Certificate that your ECC Rater (the field-verification credential we hold) submits to CHEERS at close-out. Without the CF3R, your AHJ won't sign off the final.

Common gotchas

• Ducts in unconditioned attic require the stricter "leakage to outside" test, easy to miss when the duct plan shifts from a conditioned-attic concept to a vented one mid-project.
• Envelope test fails are almost always due to thin air-sealing at top plates and bottom plates, the framers don't know about the test, so it's the GC's job to scope it in.
• Additions that connect to existing ductwork can trigger the §150.2(b) altered-duct trigger even when the architect treats it as new work, the test scope follows the new metal, not the project label.