How to Fix Cracking Space Between Window Frame and Wall

Sealant for Small Cracks

Step 1

Clean around the cracked area with a clean wet rag, wiping dirt and dust from around the crack. Allow the area to dry completely.

Step 2

Apply frame sealant for cracks between the window frame and wall that are less than 10 millimeters wide. Prepare the sealant by placing the sealant tube into a caulk gun and cutting the tip of the tube to create an opening that is roughly the same size as the width of the crack you need to fill.

Step 3

Hold the tip of the sealant container up to the crack at one end. Lightly depress the trigger on the caulk gun to push the sealant out the tip. Keep steady pressure on the trigger and move the tip down the length of the crack, squeezing sealant into the space.

Step 4

Stop pressing the trigger at each corner of the window, then begin a new line of sealant across the next crack. If large globs of sealant sit anywhere along the line, wet your finger and smooth the sealant down against the surface.

Mortar for Wider Spaces

Step 1

Clean the area with a wet rag, removing dirt from the crack. Allow the area to fully dry.

Step 2

Apply mortar to fill cracks between a window frame and wall if they are wider than 10 millimeters. Mix the mortar according to the directions on the package to get the proper consistency.

Step 3

Spray water into the cracked space to moisten, and apply mortar to the crack with a putty knife. Spread the mortar over the crack; use the tip of the putty knife to force the mortar into the crack. Continue adding mortar until the crack is filled and even with the wall.

Step 4

Remove mortar that gets on the surrounding wall with the edge of the putty knife. Wipe off any spots of mortar that remain on the wall while the mortar still is wet.

Step 5

Go over the new mortar work with sealant after three or more days when the mortar is fully set. Apply the sealant over the new mortar and smooth it down with a wet finger so it sits flat against the surface.