“But Houses Need to Breathe”: One of the Biggest Myths About Insulation

If you’ve spent any time reading comments online about spray foam insulation—or insulation in general—you’ve probably come across this one:

“Houses are meant to breathe. Insulating is bad.”

It’s a statement that gets repeated often, but it’s not entirely accurate. In fact, it’s one of the most common myths we hear in our industry.

Let’s break down what this comment really means, why it’s misleading, and how modern building science actually supports air-tight homes (when done the right way).

Do Houses Really Need to “Breathe”?

This idea comes from an older philosophy in homebuilding. Before energy efficiency became a top priority, homes were often built without tight seals, with the understanding that some degree of airflow helped prevent issues like moisture buildup and stale air. And while it’s true that early homes were leakier, that wasn’t by design—it was by default.

Today, we understand the difference between air leakage and ventilation. The old idea that houses need to breathe gets these two concepts confused.

Here’s the truth:

• People need to breathe.
• Your furnace and air conditioning systems need to breathe.
• Your house? Not so much.

When we say a house is “breathing,” what’s actually happening is uncontrolled air leakage—air is slipping in and out of the structure through gaps, cracks, and seams in the building envelope. This isn’t helpful ventilation; it’s energy waste.

Airtight Homes Are Better Homes

When we apply spray foam insulation, we’re not just adding thermal protection—we’re also sealing air leaks. Spray foam expands into all the nooks and crannies that traditional insulation can’t reach, making your home significantly more airtight.

But here’s the important part: we’re not sealing it 100% airtight. There will always be some airflow. And in modern homes—especially new construction—mechanical ventilation is built right into the system to ensure safe, breathable air inside.

For example:

• Many HVAC systems today include fresh air intakes, which pull in outdoor air in a controlled way.
• ERVs (Energy Recovery Ventilators) and HRVs (Heat Recovery Ventilators) are also common solutions that maintain healthy indoor air without compromising efficiency.

This means you can have a tightly sealed home and still enjoy excellent indoor air quality—as long as it’s ventilated properly. In fact, you’ll get better air this way than through the random cracks and dusty crawlspaces of a “breathing” house.

What’s Wrong With a Leaky House?

A leaky house leads to a long list of problems:

• Higher energy bills as your heating and cooling systems work overtime.
• Moisture intrusion that can lead to mold and rot in walls, attics, and basements.
• Drafts that make the home feel uncomfortable, no matter what the thermostat says.
• Inconsistent temperatures from room to room.

By insulating with spray foam, we help eliminate those issues. A more controlled environment is not just more comfortable—it’s safer, healthier, and more cost-effective.

The Real Solution: Control the Airflow

Good building science isn’t about letting a house “breathe” randomly—it’s about controlling the way air moves in and out.

Spray foam allows us to create a tight building envelope, and then the rest of your home’s systems—like HVAC and ventilation—take over to ensure healthy air exchange.

This strategy gives you:

• Consistent indoor temperatures
• Lower utility bills
• Less wear on HVAC systems
• Cleaner, filtered air
• Fewer allergens and pollutants entering the home

In other words, it’s a win across the board.

So Where Did the Myth Come From?

Many older homes weren’t sealed well, and they survived just fine—drafty, but fine. Builders and homeowners alike got used to the idea that “some air needs to get in.” But what wasn’t well understood at the time was that uncontrolled air brings uncontrolled problems—especially moisture.

Today’s codes and best practices are smarter. We now design homes to be sealed and insulated properly, then intentionally ventilated through mechanical systems that can be cleaned, adjusted, and maintained.

This isn’t guesswork. It’s science-backed building strategy—and it works.

Final Thoughts

At Indiana Spray Foam, we hear all kinds of questions on social media, and we’re glad people are asking. We believe in helping homeowners understand not just what we do, but why it works.

So next time someone says “houses are meant to breathe,” remember: what they’re really saying is “houses are meant to leak.” And we can all agree—leaks are never a good thing.

When done right, spray foam insulation seals your home, improves your comfort, and helps your ventilation system do what it was designed to do: keep you breathing easy, in a healthy, energy-efficient space.