Can You Test Both New Construction and Existing Homes?

Blower door testing isn’t just for new construction. This article explains how blower door tests are used for both new builds and existing homes, what the differences are, and why each benefits from testing. Learn how builders use blower door testing for energy code compliance, while homeowners use it to diagnose drafts, comfort issues, and energy loss throughout Middle Tennessee.

Yes. Blower door testing is not just for brand-new homes trying to pass inspection. It’s just as valuable, and often more eye-opening, for existing homes dealing with comfort issues, high energy bills, or moisture problems.

Whether you’re a builder finishing a new project or a homeowner living in a house built 20, 40, or even 100 years ago, blower door testing provides real data about how your home performs. The purpose is the same in both cases: identify uncontrolled air leakage and understand how air is moving through the structure.

The difference is why the test is being done and what happens after.

Blower Door Testing for New Construction Homes

For new construction, blower door testing is primarily about code compliance.

In Middle Tennessee and most jurisdictions following the International Energy Conservation Code (IECC), new homes are required to meet a specific air tightness threshold. This is measured in air changes per hour at 50 Pascals, commonly referred to as ACH50.

Why New Builds Need Blower Door Testing

Blower door testing on new construction helps:

  • Verify the home meets local energy code requirements
  • Confirm the building envelope was installed correctly
  • Catch air leaks before final inspection
  • Avoid failed inspections and costly rework
  • Ensure the home performs as designed

New homes may look airtight, but appearances lie. Even high-end builds with spray foam insulation can fail if air sealing details are missed. Top plates, attic penetrations, garage interfaces, and mechanical chases are common problem areas.

Testing provides objective proof that the home meets standards inspectors require.

When New Construction Is Tested

New construction blower door testing happens at the appropriate inspection phase, typically:

  • After insulation is installed
  • After windows and exterior doors are in place
  • When the air barrier is complete
  • Before final finishes when possible

Testing at this stage allows issues to be corrected quickly and inexpensively. Waiting until final inspection often turns small fixes into big headaches.

Blower Door Testing for Existing Homes

Existing homes are tested for a completely different reason. Here, the focus shifts from code compliance to diagnosis and improvement.

Many homeowners live with problems they assume are normal:

  • Drafty rooms
  • Uneven temperatures
  • High heating and cooling bills
  • Excess humidity or dryness
  • Dust, allergens, or musty smells

A blower door test shows why these issues exist.

What Blower Door Testing Reveals in Older Homes

For existing homes, a blower door test can:

  • Identify where conditioned air is escaping
  • Reveal where outside air is entering uncontrolled
  • Expose hidden envelope failures
  • Help prioritize air sealing improvements
  • Improve comfort and indoor air quality

Older homes were rarely built with modern air sealing standards. That doesn’t mean they’re bad homes. It just means air moves through them freely, often in ways that hurt comfort and efficiency.

Testing replaces guessing with measurable data.

Is There a “Pass or Fail” for Existing Homes?

No. Existing homes are not tested to “pass” or “fail.”

Instead, results are used to:

  • Understand how leaky the home is
  • Compare performance to similar homes
  • Identify improvement opportunities
  • Guide energy efficiency upgrades

Lower ACH numbers indicate tighter homes, but tighter is not always better without proper ventilation. The goal is controlled air movement, not sealing a home shut.

A blower door test gives homeowners clarity, not judgment.

How the Testing Process Is the Same for Both

The actual test procedure is the same whether the home is brand new or decades old.

We use:

  • A calibrated blower door fan mounted in an exterior door
  • Digital pressure gauges
  • Controlled pressure differences to measure airflow

The equipment depressurizes or pressurizes the home to simulate natural pressure forces like wind and stack effect. From there, airflow is measured and analyzed.

Same test. Different goals.

Builders and Homeowners Both Benefit

Blower door testing serves different needs, but the value is real in both cases.

For builders:

  • Faster inspections
  • Fewer failed tests
  • Better consistency across projects
  • Fewer callbacks after occupancy

For homeowners:

  • Lower utility bills
  • Improved comfort
  • Reduced moisture intrusion
  • Better indoor air quality

In both cases, the test provides insight that visual inspections alone cannot.

What About Renovations or Additions?

Homes undergoing major renovations or additions also benefit from blower door testing.

Testing before and after work allows you to:

  • Measure improvement
  • Verify air sealing work
  • Avoid creating pressure imbalances
  • Ensure upgrades perform as expected

This is especially helpful for homeowners investing in insulation, window upgrades, or HVAC improvements.

Serving New and Existing Homes Across Middle Tennessee

We provide certified blower door testing for both new construction and existing homes throughout Middle Tennessee, including Nashville, Franklin, Murfreesboro, Columbia, and surrounding areas.

Whether you need documentation for an inspector or answers about why your home feels uncomfortable, testing gives you real information to work from.

Final Answer

Yes, we test both new construction and existing homes.

For new builds, blower door testing ensures code compliance and smooth inspections. For existing homes, it diagnoses air leakage, comfort issues, and energy loss.

Different reasons. Same proven process. Real results either way.