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  • How to Seal Air Leaks with Caulk

    Project difficulty: Easy

    Estimated energy savings: 5-20%*

    Time to complete: 1-2 hours

    Materials needed: Caulk gun, caulk, putty knife, stiff brush or large screwdriver, paper towels or rag

    According to the U.S. Department of Energy, a typical family spends nearly $2,000 each year on energy bills (gas and electric) in the United States today. Unfortunately, some of that money is squandered due to leaking windows, doors, old appliances or inefficient heating and cooling systems. 

    Replacing old windows and appliances with more energy efficient ones is not always budget-friendly, but using caulk to seal air leaks can be a great way to help your family save money on energy bills. 

    So grab a caulk gun and spend an hour or so sealing the air links around your house. You’ll be surprised how a little effort can make a significant difference in the amount of energy your home consumes. The steps below, based on a do-it-yourself project from the U.S. Department of Energy, make it easy to get started.

    1. Clean all areas where caulk needs to be applied. Use a putty knife, stiff brush or large screwdriver to remove old caulk and paint. It’s important to make sure the area is completely dry before applying caulk to avoid sealing in moisture. 
    2. Cut the tip of the caulk tube at a 45-degree angle and insert the tube into the caulking gun. If this is your first time using a caulk gun, you may want to practice dispensing the caulk on a paper towel first.  
    3. Hold the caulking gun at a 45-degree angle to the dry, clean edge that needs to be sealed. Press down on the caulk gun trigger and use a pulling motion to slide the nozzle along the window seal. The caulk should be immediately forced into the crack as soon as it comes out of the tube if applied correctly.
    4. Every couple of feet, push the caulk you've just applied into the crack with a damp finger, knife or other object. 
    5. Use a damp rag to clean up any excess caulk right away as it is difficult to remove once dried. 
    6. Typically, it takes 12-24 hours for the caulk to completely dry, depending on the air temperature and humidity. Read the instructions on the caulk package for more information. 

    If you're not sure which windows or other areas need to be sealed with caulk, the DIY Network suggests holding a lit candle close to suspected gaps on a windy day. If the flame moves toward you, air is likely pushing through. You can concentrate your caulking efforts on those areas.  

    *The U.S. Department of Energy says you can save up to 20% on total energy costs with this project, but your savings will depend on the state of your home and the type and condition of your HVAC unit. http://energy.gov/energysaver/projects/savings-project-how-seal-air-leaks-caulk