Air Sealing Attics: The Basics

An often-overlooked aspect of home energy efficiency, air sealing attics is a task every homeowner should consider. While it may seem like a daunting task, it is relatively easy to accomplish with the right tools and knowledge. In this article, we’ll go over the basics of air sealing attics, including the benefits, how to spot areas that need sealing, materials required, and the process.

Benefits of Air Sealing Attics

There are several benefits to air sealing attics, including:

  • Improved energy efficiency: By sealing air leaks, you prevent cold air from seeping in during winter and hot air during summer, reducing the workload on your HVAC system.
  • Better indoor air quality: By stopping air from entering your attic, you help maintain the integrity of your home’s envelope and reduce the infiltration of pollutants into your home.
  • Reduced utility bills: The less your HVAC system has to work, the less energy it will consume, resulting in a significant cost savings.

Where to Find Air Leaks in Your Attic

Before you begin air sealing your attic, it’s important to identify any air leaks and seal them before applying insulation. Here are some common trouble spots to inspect:

  • Penetrations: These are openings from things like wiring, plumbing, and ductwork that allow air to pass through.
  • Attic hatch: The hatch is a common source of air leaks as it is often not sealed properly and allows air to escape into the attic.
  • Chimneys and flue stacks: Air can often escape from gaps between the chimney and the house.
  • Recessed lights: Some recessed lights do not come with an air seal, allowing air passage.
  • Roof vents and fans: These are typically sealed when they are installed, but the sealant can deteriorate over time.

Materials and Tools You Will Need

To air seal your attic, you’ll need the following materials and tools:

  • Caulk: Use a silicone-based caulk to seal gaps around plumbing vents, flues, and electrical wires.
  • Foam sealant: Foam sealant is perfect for gaps that are difficult to reach or large in size, such as pipe penetrations or gaps in framing.
  • Weatherstripping: A strip of foam or tape that seals gaps around doors and vents.
  • Attic hatch cover: A cover that rests on top of the attic hatch, creating a buffer between the attic and the living space.
  • Caulking gun: You’ll need this to apply the caulk.
  • Utility knife: Use it to cut foam and break the seal on foam cans.
  • Headlamp or flashlight: It should be bright enough to see what you’re doing.

The Process

Now that you’ve identified the trouble spots and have the materials and tools handy, you’re ready to get started. Here’s the process to follow when air sealing your attic:

  1. Begin by sealing the penetrations with caulk. Apply it generously and make sure to create a good seal.
  2. Next, seal the gaps with foam sealant. Shake the can well before use and apply in small amounts, filling the gaps until it is level with the surrounding area.
  3. Weatherstrip around the hatch. Cut the foam tape to length and press it into place around the edges of the hatch.
  4. Install an attic hatch cover. First, cut pieces of foam insulation to fit the cover. Then, place the cover on top of the hatch and screw it in place.
  5. Inspect the recessed lights. If they don’t have airtight housings, buy and install them.
  6. Finally, install a baffle at the ridge of your attic to make sure you have proper ventilation.


Air sealing your attic is a simple, yet effective way to improve your home’s energy efficiency, reduce your utility bills, and improve indoor air quality. With attention to detail, the right tools, and a little bit of patience, you can easily complete this project on your own. Remember to inspect your attic regularly to ensure the integrity of your work and make sure your HVAC system operates optimally.

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