How to Fix Cracks Between Walls & Windows

Sealing Cracks

• 1

  Brush the area around the crack with a wire brush to loosen cracked bits and residue. Vacuum the crack to remove debris and accumulated dirt. Wipe the surface with a wet rag to remove dust and residual debris. Let the wall dry completely.

• 2

  Load a cartridge of frame sealant into a caulk gun. Cut the nozzle of the sealant cartridge at a 45 degree with the tip of a sharp knife. Make the hole slightly smaller than the size of the crack you want to seal.

• 3

  Position the tip of the gun at a 45-degree angle between the wall and window. Pull the gun’s trigger to release the sealant out through sealant tube's tip and into the crack. Maintain a steady hand and apply constant pressure on the trigger as you move the sealant's tip down the crack, inserting the sealant into the exposed space. Try to apply the sealant in a straight run along the crack without stopping.

• 4

  Release the pressure on the trigger when you reach the end of this line, or the corner of the window. Position the tip of the gun at an angle along the tip of the next crack and repeat the process of filling the space with sealant.

• 5

  Scrape the sealant bulging out of the crack with the edge of a trowel so it is flush with the surrounding surface. Wipe your wet finger over the exposed sealant on the crack surface to give it a smooth finish. The sealant cures thoroughly when it forms an outer skin, usually after one to three weeks, depending on the size of the crack and the weather conditions.

Mortaring Cracks

• 6

  Clean the cracked area with a wire brush to remove loose debris and residue. Wipe the surface with a damp cloth and spray water into and over the crack.

• 7

  Mix mortar with water according to the directions on the label, using a small hand trowel to achieve a smooth, workable consistency. Scoop some mortar and insert it into the crack with the tip of the trowel. Continue to pack mortar into the crack until it is full.

• 8

  Wipe excess mortar that protrudes from the crack with the edge of the trowel, so it is flush against the surrounding surface. Let the mortar harden or cure for three to five days.

• 9

  Apply mortar sealant over the mortar work when it cures. Smooth the sealant with a wet finger so it sits flush against the wall.