Repairing Concrete Window Sills Exterior !!better!! «OFFICIAL • 2024»

After 7 days of curing (be patient!), apply a penetrating silane/siloxane sealer. Do not use a film-forming acrylic or polyurethane—these will trap moisture and cause spalling. A good sealer will bead water like wax on a car for 5-10 years.

Concrete window sills have a specific shape—a slight downward slope (a "wash") to shed water. repairing concrete window sills exterior

Regularly inspecting your sills can help catch issues before they require a full replacement. Look for: After 7 days of curing (be patient