Serving Holly Springs, Raleigh & the Triangle Region (919) 567-5329 · Text Us

Duct Leakage Testing in Raleigh & Wake County, NC

NC energy code compliance duct leakage testing for newly installed residential duct systems — mandatory under Section R403.3.3 of the 2018 NCECC. Calibrated duct blaster equipment, fast turnaround, detailed reports — designed for builders and HVAC contractors who need reliable, hassle-free testing.

The 2018 NC Energy Conservation Code requires every new residential duct system to pass a duct leakage test. The code limits total duct leakage to ≤5 CFM25/100SF and duct leakage to the outside to ≤4 CFM25/100SF, tested at 25 Pa. We test, document compliance, and help you pass the first time.

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What Is Duct Leakage Testing?

Duct leakage testing measures how much conditioned air escapes from a duct system. Using calibrated equipment, we depressurize the ducts to -25 Pascals and measure total leakage — then normalize the result to your system's conditioned floor area.

The duct blaster fan depressurizes the entire duct system to a standardized -25 Pa. As the system depressurizes, air is drawn in through cracks, seams, unsealed penetrations, and poor connections. We measure this leakage in CFM25 (cubic feet per minute at -25 Pascals).

The result is then normalized by dividing total CFM25 by 100 square feet of conditioned floor area served. This gives a standard metric — CFM25/100SF — that allows consistent comparison across projects of different sizes.

North Carolina Residential Code sets a maximum of 4.0 CFM25/100SF for outside duct leakage (ducts running through unconditioned spaces like attics, crawlspaces, and garages), and 5.0 CFM25/100SF for total duct leakage (all ducts combined).

Duct Blaster Equipment

Calibrated fan depressurizes system to -25 Pa and measures leakage flow in real time

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CFM25 Measurement

Total air leakage at -25 Pa, then normalized to conditioned floor area

Pass/Fail Report

Clear documentation of leakage, threshold, and compliance status for code officials

Leak Identification (Optional)

Pressure pan testing to help locate where air is escaping

Duct blaster equipment setup
in new construction attic duct-blaster-equipment-setup.webp

North Carolina Residential Code Requirements

NC Residential Code mandates duct leakage testing for all newly installed residential duct systems. Here's what contractors need to know.

Per NC Residential Code Section R403.3.6, duct leakage limits depend on duct location:

≤4.0CFM25/100SF — Ducts outside thermal envelope (attic, crawlspace, garage, exterior wall cavities)
≤5.0CFM25/100SF — Total duct leakage (all ducts combined)

Testing Requirements:

Required for all newly installed residential duct systems — no exceptions
May be performed at rough-in (before insulation/drywall) or final inspection
Total duct leakage test requires a calibrated duct blaster or equivalent duct pressurization equipment
Outside duct leakage test requires both a duct blaster and a blower door operated simultaneously
Report must be submitted to building inspector for permit sign-off
If testing shows FAIL, ducts must be sealed and retested until PASS is achieved

We're familiar with Wake County and Triangle-area inspector requirements. If you have questions about local code variations, ask — we can advise.

Our Duct Leakage Testing Process

We keep the process simple and fast. Confirm, schedule, test, document, deliver. Same-week availability for most projects.
1

Confirm System Ready

Before scheduling, the contractor should confirm the duct system is completely installed, sealed, and ready for testing. Incomplete systems or missing connections will result in a failed test.

2

Schedule (Same-Week Availability)

Call, text, or email to book your test. We work around builder and HVAC contractor schedules — most tests can be scheduled within 1–3 business days.

3

Equipment Setup

We set up at the main indoor return. The HVAC air handler must be closed and completely sealed. All registers are sealed, dampers open, system clean and dry.

4

Depressurize to -25 Pa

The duct blaster fan depressurizes the entire system to -25 Pascals. We monitor system pressure stability and measure the air drawn in through leaks.

5

Measure & Normalize

We record total CFM25 leakage and normalize it to your conditioned floor area (CFM25/100SF). The result is compared against NC code threshold (4.0 CFM25/100SF outside leakage or 5.0 CFM25/100SF total leakage).

6

Document Results

We provide a formal test report showing total leakage, PASS or FAIL status, and code compliance. Reports are formatted for builder/inspector records and include equipment serial numbers and calibration dates. We also complete and provide the North Carolina Energy Efficiency Certificate.

7

If Needed: Leak Identification

If the system fails, we can perform pressure pan testing to help locate where air is escaping. We mark leak locations so your HVAC contractor can seal them efficiently.

Duct leakage test in progress
technician with duct blaster fan duct-leakage-test-in-progress.webp

What If You Fail? We Help You Pass.

System fails the test? We're not here to shut you down — we're here to help you identify the problem and fix it fast.

If your initial test shows leakage above the applicable code threshold, here's how we handle it:

1Pressure Pan Testing — We use visual and tactile methods (pressure pans, smoke, etc.) to locate leak sources. Common culprits: unsealed duct transitions, poor takeoff connections, gaps around penetrations, unsealed dampers.
2Mark Locations — We clearly identify where air is leaking so your HVAC contractor knows exactly where to seal.
3Contractor Seals — Your HVAC installer uses mastic, aeroseal, or other approved methods to seal the identified leaks.

To keep things moving smoothly, please have the system ready before we arrive. We're happy to stay on-site to help identify leaks and assist with the repair process — just know that additional testing time and on-site waiting while repairs are made is billed separately. If a full retest is needed after repairs are complete, we'll schedule that as a new appointment.

Why Contractors Choose Peak Energy for Duct Testing

We understand builder and HVAC contractor workflows. Fast, reliable, professional — nothing more, nothing less.

You're on a schedule. We get that. Our goal is to make duct testing the easy part of your project, not a bottleneck.

Same-Week Scheduling — We work around your timeline, not the other way around
Calibrated Equipment — All duct blaster equipment is professionally maintained and calibrated
Clear, Detailed Reports — No confusion about pass/fail. Reports include all data needed for inspector sign-off, including the NC Energy Efficiency Certificate.
Leak Identification Included — If you fail, we help you find the leaks. No guessing.
Familiar with Local Inspectors — We know Wake County and Triangle-area building officials. No surprises, no rejected reports.
Also Offer Blower Door Testing & HVAC Airflow Testing — One call for all your code compliance testing needs

Frequently Asked Questions

What is duct leakage testing?

Duct leakage testing measures how much conditioned air escapes from a duct system using a duct blaster fan that depressurizes the system to -25 Pascals. Results are reported in CFM25 (cubic feet per minute at -25 Pa) and normalized to CFM25/100SF of conditioned floor area. NC code limits outside duct leakage to 4 CFM25/100SF and total duct leakage to 5 CFM25/100SF.

When is duct leakage testing required in North Carolina?

Per NC Residential Code, duct leakage testing is required for any newly installed residential duct system. Outside duct leakage must not exceed 4 CFM25/100SF; total duct leakage must not exceed 5 CFM25/100SF. Testing may occur at rough-in or final inspection.

How long does a duct leakage test take?

Duct leakage testing typically takes about one hour per system.

How much does duct leakage testing cost?

Duct leakage testing is $250 per system. Additional travel charges may apply depending on location. Outside duct leakage testing — which requires a blower door in addition to the duct blaster — is an additional $150.

What payment methods do you accept?

Payment is due at time of service. We accept Zelle, Venmo, check, or cash. Contractors with a pre-approved account may be set up for invoiced billing — contact us to arrange.

What happens if my system fails the duct leakage test?

If a system fails, we help identify leak locations using pressure pan testing and other diagnostics. We report which ducts are leaking and where — then your HVAC contractor can seal those areas (typically with mastic or aeroseal). A retest is scheduled as a separate appointment once repairs are complete.

Can the HVAC contractor be present during testing?

Yes — and we recommend it. The contractor should be present to observe results, see where leaks are located (if any), and understand the remediation needed. This keeps the project moving and avoids surprises.

What documentation will I receive?

We provide a detailed test report showing total leakage in CFM25 and CFM25/100SF, PASS or FAIL status, and the code threshold your system must meet. Reports include equipment serial numbers, calibration dates, and are formatted for builder and inspector records.

Need North Carolina Code Compliance Testing?

Peak Energy provides fast, reliable duct leakage testing for builders and HVAC contractors across Wake County. Same-week scheduling available.

Schedule Your Test

Or call (919) 567-5329