What's the Difference Between Insulation and Air Sealing?

February 5th, 2025 by Justine Zimny

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What is Insulation?

Insulation refers to materials that resist the flow of heat, either keeping it inside during the winter or outside during the summer. Insulation is typically placed in areas such as the attic, walls, floors, and ceilings to reduce the need for heating and cooling. By improving insulation, you help maintain a stable indoor temperature and reduce the amount of energy required to heat or cool your home.

Types of Insulation:

Batt Insulation: Pre-cut fiberglass or cotton panels that are placed between wall studs, ceiling joists, and floor joists.
Blown-In Insulation: Loose-fill materials like cellulose or fiberglass that are blown into attics or walls.
Spray Foam Insulation: Expanding foam that fills gaps, cracks, and cavities, providing a high R-value and excellent air sealing properties.

Benefits of Insulation:

Temperature Regulation: Keeps your home warmer in the winter and cooler in the summer.
Energy Efficiency: Reduces the need for excessive heating and cooling, leading to lower utility bills.
Noise Reduction: Helps to reduce sound transmission between rooms, making your home quieter.
Increased Comfort: Prevents hot or cold spots in your home, leading to a more consistent temperature throughout.

What is Air Sealing?

Air sealing refers to the process of closing gaps, cracks, and holes in a home’s envelope (the outer walls, roof, and floors) that allow air to leak in or out. While insulation reduces heat transfer, air sealing focuses on preventing drafts and unwanted airflow. Common areas for air leaks include around windows and doors, electrical outlets, recessed lights, attic hatches, and gaps in the foundation or around pipes.

Common Air Sealing Methods:

Caulking: Used to seal cracks around windows, doors, and trim.
Weatherstripping: Applied around doors and windows to prevent air from entering or escaping.
Spray Foam: Expands to fill gaps and cracks, especially around areas like pipes, ducts, and wires.
Foam Board Insulation: Can be used in areas where air leaks are significant, like basements or attics.

Benefits of Air Sealing:

Prevents Energy Loss: Stops warm or cool air from escaping, reducing the need for heating or cooling.
Improves Indoor Air Quality: Keeps dust, pollutants, and outdoor allergens from entering your home.
Increases Comfort: Eliminates drafts and keeps temperatures even throughout your home.
Boosts Insulation Effectiveness: Proper air sealing enhances the performance of insulation, as it prevents air from bypassing the insulation.

How Insulation and Air Sealing Work Together

While insulation helps to slow down the transfer of heat, air sealing prevents the movement of air. These two elements work in tandem to create a comfortable, energy-efficient home. For example, without proper air sealing, heated or cooled air can escape through cracks and gaps, making it harder for insulation to maintain your home’s temperature. Similarly, without sufficient insulation, your home may still feel drafty, and your heating and cooling systems will have to work harder.

Why Both Are Essential:

Insulation alone can’t stop air from moving through gaps and cracks. Without air sealing, even the best insulation will lose its effectiveness.
Air sealing alone may reduce drafts, but it won’t improve temperature regulation without insulation to slow heat transfer.

Which Should You Address First: Insulation or Air Sealing?

The general recommendation is to address air sealing first, followed by insulation. This is because sealing air leaks first ensures that you don’t trap any unwanted air in your home when you add insulation. Once the gaps and cracks are sealed, you can add insulation to the areas that need it most, providing long-term energy efficiency.

In Summary:

Insulation slows down the flow of heat, helping to keep your home warm in winter and cool in summer.
Air Sealing prevents unwanted air from entering or exiting your home, stopping drafts and improving indoor air quality.
Together, insulation and air sealing create a more comfortable, energy-efficient, and environmentally friendly home.

For the best results, it’s important to address both insulation and air sealing. A home energy audit can help you identify the areas where improvements are needed. By upgrading both your insulation and air sealing, you can maximize comfort, reduce energy costs, and improve your home’s overall energy efficiency.