Quick answer. Pennsylvania, New Jersey and Delaware all require a blower door test on a new home, and the limit on the prescriptive path is 3.0 ACH50 in each. What differs is the code edition in force, when ducts have to be leak tested, and who is allowed to do the testing. Choose your location below for the details.
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Requirements at a glance
| Location | Energy code in force | Blower door limit, prescriptive path | Duct leakage test |
|---|---|---|---|
| Pennsylvania | 2021 energy code, since January 1, 2026 | 3.0 ACH50 | Required, unless the ducts and air handler are entirely inside the insulated envelope |
| Philadelphia | 2021 energy code with city amendments, for all permit applications from July 1, 2026 | 3.0 ACH50 | Required in every case |
| New Jersey | 2024 energy code, since August 17, 2026. The 2021 code is accepted for applications through February 17, 2027 | 3.0 ACH50 | Required for every duct system |
| Delaware | 2024 energy code, adopted April 11, 2026. Counties and towns have until April 2027 to enforce it | 3.0 ACH50 | Required for every duct system under the 2024 code |
ACH50 is the number of air changes per hour at a test pressure of 50 pascals. Lower is tighter.
Pennsylvania
- The 2021 energy code took effect statewide on January 1, 2026.
- The prescriptive blower door limit dropped from 5 ACH50 to 3.0 ACH50.
- Duct systems must test at 4 CFM25 per 100 square feet or lower. No duct test is required when the ducts and air handler are entirely inside the envelope.
- There is no statewide tester license. The local code official decides whether an approved third party is required.
Pennsylvania blower door and duct leakage test requirements
Philadelphia
- Philadelphia follows the same 2021 code with its own amendments, in force for all permit applications from July 1, 2026.
- A duct leakage test is required even when the ducts are inside the envelope. The limit in that case is 8.0 CFM25 per 100 square feet.
- An additional energy efficiency package is required.
- Testing is a special inspection under the city building code, and the reports are due before final inspection.
Philadelphia energy code: blower door and duct testing requirements
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New Jersey
- The 2024 energy code took effect on August 17, 2026. A complete permit application submitted through February 17, 2027 can still be reviewed under the 2021 code.
- Every duct system is leak tested, including ducts inside conditioned space.
- Under the 2024 code the duct leakage limit depends on the number of ducted returns and the stage of installation.
- The tester must be a third party who is independent of the installer and approved by the local code official.
New Jersey blower door and duct leakage test requirements
Delaware
- The state adopted the 2024 energy code effective April 11, 2026. Counties and towns have 12 months to bring their own codes into line, so the date depends on where you build.
- Sussex County requires the 2024 code from April 11, 2027.
- Under the 2024 code every duct system is leak tested.
- Testing must be done by a certified Duct and Envelope Tightness (DET) verifier.
Delaware blower door and duct leakage test requirements
Sources
Each page above lists the official sources for its location: the state and city regulations, the adoption notices, and the code text.
This page summarizes the code for builders and is not legal advice. Confirm the details of your project with your local code official.
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