Does My House Need To Breathe?

“Doesn’t my house need to breathe?”

At South Central Services, we answer this question from curious homeowners almost daily. They hear about air-sealing as they read more about spray foam insulation or speak to the contractors who install it.

From the insulation perspective, the idea of sealing off every crevice of their home for temperature control makes sense. But doesn't it also trap the air inside? Shouldn’t the house have some air flow?

By the end of this article, you'll understand:

• What it means for a building to breathe
• Why controlling air ventilation is the best practice
• How to circulate air in an air-sealed home

Don't have time to read right now? Check out everything you need to know at a glance.

What Does It Mean For A Building To Breathe?

Living leads to indoor air pollutants. Gasses, moisture, and dust build up and reduce the air quality. Fresh air from outside must be exchanged to improve that air quality.

The building science concepts that allow air to exchange are ventilation and circulation. The phrase "a house needs to breathe" refers to the ventilation and circulation of air.

Ventilation refers to letting indoor air pollutants out of a building and allowing fresh air from outside in. Once the air is inside, it must circulate so all corners of the building experience this fresh air.

Do Buildings Need To Breathe?

Do buildings need ventilation and circulation? Yes. Without ventilation, homes would be smelly and stale. But building science has improved. We no longer have to let air trickle in through joints, cracks, doors, and windows.

Air-sealing prevents air from entering these places, forcing ventilation through specific building design sites. Examples would include bathroom fans, kitchen range hoods, dryer vents, and HVAC systems.

How Does Air Ventilation Work In An Air-Sealed House?

In an air-sealed house, air ventilation is controlled by mechanical ventilators. These include the HVAC system, heat recovery ventilators (HRV), and energy recovery ventilators (ERV). Every home does not need all of these ventilation machines. The design of a building will determine the best mechanical ventilation system.

These mechanical ventilators exchange the air from inside and outside the home. Rather than letting air leak randomly, the indoor air pollutants are sent outside, and the fresh outside air is passed through a filter and brought into the home.

Air can also ventilate through natural ventilation, which is as simple as opening a window or a door. Air from natural ventilation is not filtered, so some outdoor air pollution may be present. We also cannot control the temperature or the humidity of air with natural ventilation.

Air-sealed homes with proper HVAC ventilation systems are more comfortable, more affordable to live in, and have better indoor air quality.

Why Should I Control The Air Circulating In My Home?

We never used to control the air from the outside, so why would we be advocating for regulating it now? You should control the air that circulates in your home for three reasons.

1. Outdoor air pollution
2. Moisture and humidity
3. Home comfort

Let's examine each of these in more detail.

1. Outdoor Air Pollution Can Infiltrate Your Home.

We've discussed indoor air pollution already. But the air from outside is not always pure, either. Air pollution from vehicles and factories are common examples. Your neighbors may burn their trash, introducing smoke and soot to the air. The air can also have high levels of pollen, dust, tree dander, and other outdoor air pollutants.

In our area of Pennsylvania, factory pollution is less of a concern. Instead, there is more farmland. If the air outside of your home smells like manure, you probably don't want that odor leaking inside.

2. Moisture And Humidity Can Cause Mildew, Mold, And Wood Rot.

Depending on your climate, humidity may hang in the air. If that air ventilates into your home through cracks and gaps, it brings moisture with it. The increase in humidity will cause discomfort and force your HVAC system to run more to compensate. Homes constructed of wood can be at risk of mold or rot.

Even the air from your bathroom vents and kitchen range hood can cause mildew and mold. These vents should terminate outside of your home, so that excess humidity does not circulate throughout your living space.

3. Air Infiltration Causes Discomfort Through Heat, Cold, And Humidity.

Every house is different, from design to layout to materials. The combination of these factors can lead to discomfort in the home if the air is not being controlled.

Air that infiltrates through the attic can make homes unbearably hot in the summer. Constantly running fans and the air conditioning is the only way to be comfortable.

As air exits through the roof in the winter, it is replaced with freezing air from a basement or crawl space. If this air infiltration is not controlled, a comfortable living temperature cannot be maintained.

Even though winters haven't been as snowy in Chambersburg for the last several years, our climate still has enough severely cold days where we feel and battle the chill in our homes.

How Much Will Air-Sealing And Circulation Cost Me?

The biggest percentage of air-sealing efforts in a home depend on insulation. Spray foam insulation is the premier option for creating an airtight seal, but it is expensive.

You can expect to spend as much as three times more on spray foam than on traditional insulation like fiberglass.

Homeowners are not always told that air-sealing can save them money. Specifically, homes insulated with spray foam have different HVAC requirements than homes insulated with fiberglass. Usually, spray foam insulated homes require smaller HVAC systems to maintain the indoor air climate. A smaller HVAC system with different specifications can save money.

However, some of the money saved on HVAC may be spent on investing in an ERV. The cost of an ERV will vary, but you could spend somewhere between $1,500 and $3,000.

The Bottom Line About Whether Or Not Houses Need To Breathe

Spray foam insulation contractors are not recommending to seal your home and breathe the "inside" air forever. The idea behind air-sealing is to prevent air infiltration, which increases energy efficiency, improves air quality, and offers more consistent climate control. Instead of leaking at random, air can be controlled with mechanical ventilation.

South Central Services has years of experience in spray foam insulation and HVAC. Durable and comfortable homes are constructed by builders and contractors who work together to ensure optimal air quality.

If you're ready to insulate with spray foam, you will need to pick a great contractor. Check out our guide to choosing a reliable spray foam installer.

Now that you understand why your house doesn't need to breathe, your next step is to:

• Estimate the cost of spray foam insulation upgrades for your home
• Discover if it's possible for a home to have too much insulation
• Learn the three ways that heat travels throughout your house