Repair: Cement Window Sill

For small cracks, use a masonry-grade filler or a concrete repair mortar. For larger voids, you may need to apply a bonding agent before pressing the mortar into place.

Your window sills are the eyebrows of your home’s facade. When they are cracked and sagging, the whole house looks tired. With a weekend of work and about $50 in materials, you can restore that curb appeal—and more importantly, keep the weather outside where it belongs.

Concrete won't stick to old, dusty concrete. You need a bonding agent (often a milky liquid). Paint this onto the exposed area. This acts as the glue that locks your new repair material to the old sill.

Repairing a cement or concrete window sill is a common maintenance task that prevents water from seeping into your walls and causing structural damage. Most small to medium cracks can be fixed with a few standard tools and a masonry repair kit. Common Issues and Causes

are the cracks you're seeing on your sill? Knowing the scale can help determine if a simple filler is enough.

Level the filler with a putty knife or trowel. Ensure it follows the original "slope" of the sill to keep water flowing away from the building.

Replacing a cement sill is a heavy, expensive job involving sledgehammers and masonry skills.