How to Caulk Your Windows

Window caulking

Taking the time to caulk around external windows can really help lower your home utility bills– especially if it’s accompanied by installing other energy efficiency measures in your Connecticut home.

But how do you caulk an exterior window? Here’s a step-by-step guide.

  • Assess your house. Determine how many windows need to be caulked, and approximate the amount needed for each window.
  • Shop for materials. If you don’t already have one, you will need a caulking gun to apply the caulk (caulk comes in a tube). But the biggest decision you need to make is what kind of caulk you want to use – each type has its own properties, strengths, and weaknesses. For a brief explanation of the types of caulk that can be used for windows, see this link.
  • Keep an eye on the weather. Exterior caulk should be applied when the temperature is at least 45 °F with low humidity. Since the caulk may take 24 hours or more to dry, you will have to plan ahead to make sure you have a window of clear, dry weather.
  • Start easy. Choose windows on the ground floor before moving up to higher ones.
  • Prepare your windows. New caulk adheres best to clean surfaces, so remove old caulk using a putty knife. Repair damaged window frames, along with anything that will keep the caulk from adhering (dirt, old paint, etc.).
  • Prepare the caulk gun. Check out this video to see how to do it.
  • Apply a “bead” of caulk. Press the tip of your caulk gun firmly against one corner of the window and apply caulk to the next corner in a continuous bead, just thick enough to fill the gap. Press the release mechanism to stop the flow of caulk. Continue around all 4 sides.
  • Remove excess caulk. This process is called “tooling.” Use a popsicle stick or your finger (depending on the type of caulk – see manufacturer’s warnings for more information) to get the bead uniform and ensure even coverage.
  • Allow the caulk to dry for at least 24 hours. Caulk may still be unstable for up to a day after application; leave it alone to give the caulk a chance to fully dry in place.

Not a DIYer? Schedule a home energy audit with CMC Energy Services and you could get your windows caulked by the pros! Weatherizing your home is part of the more than $1,100 worth of energy-saving measures that our average customer gets undergoing a comprehensive energy audit – all for a one-time co-pay of just $149 for electric or gas heated homes; $174 for propane heated homes.

“Their technicians did great work—very professional and neat. I’m going to tell all my friends about the program.”

James L.

“Their technicians were fabulous and an asset to the company. I am very happy that I had the program done.”

Sally O.