Everything You Need to Know About Sealing Attic Air Leaks

Does it feel drafty every time you venture into your attic? It might be time to consider sealing your attic air leaks to put a stop to a common energy-efficiency mistake. Air leakage doesn’t only affect the attic’s temperature, but it can also majorly increase your energy bills and result in other consequences such as unwanted pests. Check out these X tips to seal your attic air leaks for good.

1. Check Common Culprits for Air Leaks

The first step to sealing any air leaks in your attic is locating the leaks, gaps, and holes that let in drafts. You will find most air leaks around chimneys, light fixtures, plumbing pipes, ventilation, wiring holes, rafters, windows, and doors. 

When searching for air leaks, look for warning signs like dirty insulation, or hold up your hand to detect air movement. Ensure that you’re extra cautious when poking around electrical or wiring components.  

2. Use a Candle to Survey the Attic

After looking in those common spaces for air leaks, you can test the air within these areas—all you need is a candle or an incense stick. If you hold up the flame or smoke, look for erratic movements that indicate air movement. Hold up your hand, and if you feel cold air, there’s an air leak. Of course, you should avoid moving the flame too close to flammable objects or surfaces.

3. Ensure You Have Necessary Tools

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Once you identify the gaps and leaks in your attic, the next step is to decide whether you’ll seal the areas yourself or hire a professional to tackle the job. Sealing attic air leaks is manageable for many homeowners, but it’s crucial to get proper tools before jumping into the project. Keep in mind that the cost of purchasing the tools to make this repair may outweigh the price of hiring a local insulation contractor. 

The necessary tools for DIY sealing attic air leaks include:

• Caulk gun

• Dust mask

• Flashlight or headlamp

• Knee pads

• Safety glasses

• Utility knife

• Insulation—batt, roll, or blown

• Garbage bags or plastic bags

• Caulk

• Foam spray

• Work gloves

4. Follow Safety Precautions 

Ensure you follow the necessary safety instructions when sealing attic air leaks yourself. For instance, you should always wear a dust mask to reduce the chances of breathing in toxins. Make sure you’re on the lookout for any exposed nails and ensure that your work area is decently lit to reduce the chance of making a repair error or causing an injury.

5. Prioritize Sealing Big Holes

If you’re tackling this project yourself, you should make a game plan that prioritizes sealing the biggest holes because that’s how you’ll save the most money and energy. You should seal the large gaps before moving onto smaller air leaks.

To fill in large leaks, cut a piece of batt or fiberglass insulation and cover it with a plastic bag to create a vapor barrier. Common sources for attic air leaks are the gaps between studs and places where the ceiling height changes—fill these drafty spots with insulation. 

6. Plug Small Holes or Gaps

Photo: Alekss / Adobe Stock

After finding and sealing the large gaps, close up any small holes or cracks that let in air. For gaps that are smaller than one-fourth inch, use weatherproof caulk to seal the area. Ensure that you use heat-resistant caulk if the air leak is near the chimney or flue areas.

If the small leak is larger than one-fourth inch, use expandable spray foam to seal the gap. You’ll typically find slightly larger leaks near plumbing vents and wiring holes. Put the insulation back in place once the caulk or spray foam is dry.

7. Don’t Ignore the Attic Door

Since the attic door is usually one of the thinner areas of the attic, it is often a source of air leaks. By adding insulation around the door, you’ll create a tighter seal. 

You can also prevent future air leaks around your attic door or windows by upgrading the weatherstripping around the area. That way, the new weatherstripping will seal the attic door or windows off from the outdoor elements, and make it easier to open and close them.

Cost to Seal Attic Air Leaks

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This is a project for which homeowners often decide to hire professional attic insulation contractors since it can be complicated and dangerous if you don’t know what you’re doing. Professional insulators will seal all the attic air leaks and install new insulation. The cost to seal attic air leaks runs between $250 to $750.