How to Re-Seal a Drafty or Leaky Exterior Window

If you suddenly feel a chill inside your home this winter, you’re not alone. Many homeowners will notice new drafts or leaks coming from their windows during cold and rainy seasons this time of year. Sooner or later, it happens to everyone.

What is the most common cause of these problems? The seals around the window edges have failed. 

Fortunately, replacing window seals is a home improvement task that homeowners often find they can successfully tackle. The suggestions below can help you re-seal your drafty or leaky exterior windows.

Recognizing Bad Window Seals

Inadequate seals can create problems for all windows, from old-school single-pane windows to modern, energy-efficient, triple-pane windows. Therefore, it is wise to inspect your windows for problems routinely. 

Sometimes damaged window seals are easy to spot. You can see worn areas, separations and cracks in the sealant material. Or you can feel the source of the draft or see moisture on the window.

Other times, faulty seals are not easy to find. To locate a suspected breach, light a candle and move it along the window’s existing seal. If the flame flickers, the seal is faulty and cold air or moisture has found a way to enter your home. If you have a broken or malfunctioning window seal, you will most likely need to replace it immediately.

Choosing a New Sealant

Before starting your project, select a new sealant. Since most hardware stores carry many types of caulking, be sure to choose a sealant meant explicitly for exterior surfaces such as windows. The right window caulking should withstand all types of elements and weather, including extreme heat, cold, rain, sleet, snow, and direct sun rays.

Often exterior caulking is made out of silicone since it works well with other exterior materials such as aluminum, metals, and glass. However, it is not paintable, so be sure to choose a silicone sealant color that works with your home’s color scheme.

Removing Faulty Window Seals

To replace a bad window seal, begin by removing the defective sealant with a standard-sized putty knife. If it resists, you can make it pliable with a caulk softener, welding torch or heat gun.

Entirely scrape away all of the old caulking. To remove every last particle of unwanted material, you can also finish with an air compressor and wipe down the area with an alcohol-based cleaner.

Installing Fresh Sealant

The easiest and most efficient way to install the new caulking is to use a quality caulking gun. After loading the sealant cartridge into the caulking gun, cut the tip to a 45-degree angle. 

Where you cut determines the width of the bead. If you cut it close to the base, it will be a wide bead. If you cut it close to the tip, it will be a thin bead. 

To apply a line of sealant:

  1. Position the nozzle alongside the exterior wall and press the trigger with even pressure.
  2. Only lay two to three feet of sealant at a time so you can shape it if necessary.
  3. Work quickly and carefully since it will begin to cure soon after application.
  4. If you make a mistake, remove the sealant, clean the area and begin again.

Replacing inadequate window seals is a great way to keep your home in good shape. It can also help you enjoy the time you spend living there.