Florida's R405 performance path frequently relies on a claimed duct leakage performance level as part of the overall energy modeling calculation — which means that claim needs to be verified through field testing before the project can pass final inspection. For contractors used to R402's prescriptive checklist, this field-verification step is one of the more significant practical differences in how R405 projects need to be managed through construction.
Because R405 modeling evaluates whole-building energy performance, duct leakage — air escaping the duct system before reaching its intended room — is one of the variables the model accounts for, since leakage directly affects real-world energy consumption. A design that claims a specific leakage target as part of its compliance calculation needs that target confirmed in the field, not just assumed based on the modeling input.
Duct leakage testing uses a calibrated fan (a duct blaster) to pressurize the duct system and measure the airflow needed to maintain a reference pressure, typically 25 Pascals. The measured leakage is compared against the threshold claimed in the R405 compliance documentation — if the installed system leaks more than that threshold allows, the project doesn't meet the compliance basis it was permitted under.
Duct leakage testing generally needs to happen before ductwork is covered by insulation or drywall for the most accurate and easiest-to-remediate results, though some testing protocols also allow or require post-drywall verification depending on the specific compliance approach used. Coordinating the test timing with the construction schedule — rather than waiting until final inspection is imminent — gives more room to address any leakage issues found.
A failed duct leakage test means the R405 compliance basis the project was permitted under is no longer valid until the system is resealed and retested. Depending on when in construction this occurs, remediation can range from straightforward (accessible connections not yet covered) to significantly more involved (reopening finished surfaces to reach hidden leakage points).
The most effective approach is treating duct sealing as a core installation step rather than a final punch-list item — sealing every connection with mastic or approved methods as it's made, and running an internal pressure check before the official test whenever possible. Contractors who build this into their standard duct installation process see far fewer failed tests than those who treat sealing as an afterthought.
Is duct leakage testing required on every Florida R405 project?
It's required whenever the R405 compliance calculation claims a specific duct leakage performance level, which is common but not universal — confirm what the specific project's compliance documentation claims.
Can duct leakage testing be done after drywall is installed?
It depends on the testing protocol used; pre-drywall testing is generally preferred since it's easier to access and correct any leakage found, though some approaches accommodate post-drywall verification.
What happens to the permit if a project fails duct leakage testing and can't retest before a deadline?
This varies by jurisdiction, but generally the project can't receive final approval until the system is resealed and passes testing — coordinating remediation and retesting promptly is important to avoid schedule delays.
Psychro.Pro helps Florida contractors plan duct leakage testing around the construction schedule and set realistic compliance targets before the R405 report is finalized.Learn more.
