How to Inject a Molding Crack

Inspect the window or door for cracks and air leaks. Even small leaks can add up. To be certain, hold a candle a few inches from t he window frame and move it slowly along the edges. Where the flame flickers, you may have a leak.

Choose the right calk to fill the crack. Calk can be injected into small openings using a tube of calking compound and a calking gun. Sillicone-based calks tend to be more flexible and longer lasting. For very large cracks, use "large gap" or expanding calk.

Load the tube of calking compound into the calking gun and snip a 1/4-inch strip from the end of the tube at a 45-degree angle. This gives you the ability to create a thin, precise "bead" of calk.

For large cracks, place the tip of the calking tube into the crack and fill it completely. For smaller gaps, run the tip of the calking tube along the crack, applying a smooth bead from end to end.

Using your putty knife, scrape over the surface of the crack, driving as much calk as possible into the gap. To complete the job, smooth the surface of the calk with a downward angled sweep of the knife, to create a surface level with the molding.