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How to seal cracks and gaps with insulation foam (and save on energy bills)

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Air leakages around a home cause significant heat loss and gain, driving up energy costs. Learn how to seal cracks and gaps with insulation foam to create a comfy, energy-efficient home.

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Gaps and cracks: a common problem for homeowners

Are you struggling to keep your home cool in the summer or warm and cozy in the winter? Is your energy bill constantly rising for no apparent reason? Sealing all cracks and gaps is the key to keeping your home cozy and energy efficient.

Even if your home looks fine, its structure naturally shifts and settles with time, forming gaps and cracks. These can be found in walls, along the basement rim joists, and around utility penetrations, and cause air leakages that fluctuate indoor temperatures and increase energy consumption. Cracks can also cause moisture and pest infiltration.

This guide explains how to seal cracks and gaps using insulation foam. When used correctly, this product can plug irregular openings in various materials such as metal, stone, concrete, bricks, and wood.

How to find cracks and gaps around your home

Before you learn how to seal cracks in concrete, use the following methods to find hidden air leakage points in your home.

  1. Sight: The first and easiest way to find gaps and cracks around your home is to conduct a visual inspection. Look closely at door and window frames, plumbing fixtures, ventilation ducts, electrical outlets, attic hatches, the foundation, and baseboards. Keep an eye out for missing caulk, insulation, or obvious openings and cracks.  
  2. Feel: Just because you can't see cracks doesn’t mean they are not there. You can detect hidden gaps by feeling for airflow. To do this, turn off anything that causes airflow, like fans and humidifiers, and shut all exterior windows, doors, and other outdoor access points. Afterward, use your palm to feel for airflow around the edges of plumbing fixtures, electrical outlets, light switches, windows, and doors. This method works best in winter when it is easier to feel for cold air. Dampen your hands to make them more sensitive to airflow. 
  3. Candle: You can also use candles and incense sticks to detect small gaps and cracks around your home. Use a smoke pen if you are uncomfortable waving around an open flame. For the best outcomes, run this test on a windy day. Switch off any appliances that burn fuel, like furnaces. Activate bathroom and kitchen exhaust fans. Light your candle or incense stick close to areas you suspect have gaps. If the smoke or flame is blown away, it shows a hidden crack.
  4. Air leak detector: The best way to pinpoint hidden gaps and cracks around your home is to use an air leak detector. You can get a thermal/infrared camera at your local hardware store and follow the directions to detect air leaks accurately.

How to seal cracks in your home

Create a cozier home with the following steps on how to seal cement cracks and other gaps in your home.

Cans of Loctite TITE FOAM Gaps & Cracks, Loctite TITE FOAM Big Gaps, and Loctite Fire Block Foam.

1. Get the necessary tools and materials: You will need:

Tip: Different foam sealants are designed for different applications, such as gaps, cracks, and fire protection. Always choose the correct product and follow all the manufacturer’s directions.

2. Clean and prepare the area: For an effective seal, apply foam sealant to clean surfaces only. Thoroughly wash dirty areas to remove dirt, dust, debris, and oil. If you’re working on a previously sealed surface, strip off the old sealant first. Allow the area to dry completely before applying insulating foam sealant.

Consider using a vacuum with a crevice attachment for tiny crevices to clear out any dirt and debris lodged deep inside the cracks. You may also need to use a utility knife to widen the crack slightly for the applicator tool.

A man applying foam insulation to a wall opening.

3. Apply foam sealant: Put on your disposable rubber gloves, shake the spray foam can, and install the applicator tool. Hold the can upside down, insert the applicator tool tip deep into the crevice, and apply the sealant. Fill the crevice to about 50%, leaving room for expansion. 

Use Loctite TITE FOAM Gaps & Cracks for small crevices up to 1 inch. For larger openings, like old, unused utility penetrations to the outside, use Loctite TITE FOAM Big Gaps (suited for gaps up to 3 inches). Lastly, use Loctite Fire Block Foam to seal areas where code requires a fire block. Its bright orange color makes it easier to spot during inspections.

4. Leave the foam to dry: Give the foam enough time to expand and cure. While drying times vary depending on the product used, most sealants cure within 24 hours.

A man trimming off excess insulation foam

5. Remove any excess foam: Use a utility knife to remove any excess foam protruding from the sealed gaps and cracks. Trim the foam flush with the surrounding surface to create a visually appealing seal. 

Most foam sealants are designed to withstand direct exposure to the elements. However, you can create an extra layer of protection and ensure longer-lasting results by covering the sealed area. For instance, you can use a more rigid exterior covering product to prevent pests from crushing or burrowing into the foam. Materials like wood trim, siding, or metal roof flashing can all help protect sealed gaps and keep drafts from returning for many years.

Alternatively, you can paint over the cured foam sealant to provide added protection and an enhanced aesthetic appearance.

6. Conduct proper maintenance: Regularly inspect sealed areas and make necessary repairs to ensure longer-lasting results.

Products used

  • Loctite Fire Block Pro Foam 12oz Can
    Loctite Fire Block Foam

    Specialty insulating foam formula designed to be fire resistant and easily identifiable to resist the spread of fire and hot gasses.

  • loctite tite foam big gaps 12oz can
    Loctite Tite Foam Big Gaps

    Seal and insulate gaps & cracks up to 3” inside or out

  • loctite tite foam gaps cracks 12oz can
    Loctite Tite Foam Gaps & Cracks

    Seal and insulate gaps & cracks up to 1” inside or out

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