Top 5 Problems a Blower Door Test Can Uncover (That Are Costing You Daily)

If your energy bills keep creeping up.
If one room in your home is always too hot or too cold.
If your HVAC never seems to stop running.

Chances are, your home is leaking money, and you don’t even know it.

As the owner of Middle Tennessee Blower Door, I run blower door tests on homes across Nashville, Franklin, Murfreesboro, and surrounding counties almost every day. And while each home is different, there’s a common theme I see over and over again:

Invisible air leaks are causing big-time energy waste and comfort issues.

In this article, I’m breaking down the top 5 problems a blower door test can uncover, problems that are likely costing you money every single day.

1. Leaky Doors and Windows

Cost Impact: 15–30% of your heating and cooling loss

Your doors and windows may look shut and sealed, but the blower door test tells a different story.

We often find:

Gaps between the frame and wall

Cracked weather stripping

Poorly installed or aging seals

Even tiny drafts around windows or sliding doors add up fast, especially during Tennessee’s hot summers and chilly winters. And while most people blame their HVAC, the real issue is often the air seeping in and out around the frame.

Fix tip: Re-caulking, weather stripping, or upgrading to energy-efficient windows can stop the bleeding.

2. Attic Leaks and Unsealed Access Hatches

Cost Impact: High energy loss & increased humidity and dust

The attic is one of the biggest culprits when it comes to air leakage. And most of the time, the leak is hiding in plain sight: the attic access hatch.

During tests, we routinely see:

• Uninsulated hatches sucking conditioned air upward
• Gaps around the trim
• Warm air escaping in winter and cool air vanishing in summer

If your attic isn’t sealed off properly, you’re essentially pumping air into an unused, often uninsulated space, and paying for it every month.

Fix tip: Foam sealants, gaskets, and insulated hatch covers make a huge difference.

3. Duct Leakage in HVAC Systems

Cost Impact: 20–40% efficiency loss

One of the most expensive surprises we uncover during blower door testing is leaky ductwork. Your HVAC system works hard to heat or cool your home, but if the ducts are leaking in your attic, crawlspace, or walls, you’re conditioning air that never even makes it to your living space.

Common issues include:

• Disconnected ducts in hard-to-see spots
• Ducts leaking at joints and elbows
• Poorly sealed returns pulling in attic or crawlspace air

Not only does this raise your utility bill, but it also causes your system to wear out faster due to constant overwork.

Fix tip: A duct blaster test (which we also offer) can isolate these leaks. Sealing or replacing faulty ductwork is one of the most cost-effective upgrades a homeowner can make.

4. Hidden Wall Penetrations and Gaps Behind Trim

Cost Impact: Constant drafts, pressure imbalance, poor air quality

Blower door tests often reveal airflow in places you’d never expect, like behind baseboards, through electrical outlets, or around plumbing penetrations. These gaps often go undetected during construction or renovations.

You might not see them, but the airflow from:

• Gaps behind light switches and outlets
• Plumbing holes under sinks and in walls
• Cracks where floors meet walls

…can create subtle drafts and pressure imbalances that make rooms feel stuffy, cold, or uneven. It also allows outside air, and allergens, to sneak in.

Fix tip: Outlet gasket covers, foam sealant, and backer rod can quickly address many of these issues.

5. Stack Effect (Hot Air Rising Out, Cold Air Rushing In)

Cost Impact: Year-round inefficiency & inconsistent room temps

Ever heard of the stack effect?

It’s a natural phenomenon where warm air rises and escapes through the upper parts of your home (attic, vents, recessed lighting), which pulls cold air in from lower levels (basement, crawlspace, or lower windows).

The blower door test makes this visible by showing:

• Excessive leakage up top (causing heat loss in winter)
• Uncontrolled cold air entry below (causing AC spikes in summer)

This creates a constant yo-yo effect that keeps your HVAC fighting a losing battle, and leads to inconsistent temperatures between floors or rooms.

Fix tip: Sealing top-floor leaks and improving attic insulation interrupts the stack and brings balance.

How Much Is It Costing You?

Here’s what the Department of Energy estimates:

"Air leaks can account for 25–40% of a typical home’s heating and cooling costs."

For a Middle Tennessee homeowner spending $250/month on utilities, that could mean $1,000+ per year, literally leaking into the air.

The Bottom Line: What You Can’t See Is Hurting You

Most homeowners assume their insulation is doing all the work.
But without proper air sealing, even the best insulation won’t stop energy loss.

A blower door test is the only way to actually measure where and how badly your home is leaking. And the results are immediate, visual, and often fixable with simple, affordable solutions.

Want to Know What Your Home Is Hiding?

If you’re curious (or concerned) about your energy loss—or if you’ve noticed high bills, drafts, or stuffy rooms—let’s schedule a test.

Call or Text Chris Lewis
Serving Nashville, Franklin, Murfreesboro & All of Middle Tennessee
www.middletennesseeblowerdoor.com

Let’s find what’s costing you, and fix it before next month’s utility bill shows up.

Chris Lewis