Repair Window Sill Concrete

A window sill is the bottom portion of the window and usually but not always has a lip that overhangs the trim molding and over time these can get damaged or even rot.

Repair window sill concrete.

Repairing window sills isn t a hard diy and i try to share simple ways to make diy improvements to your home. Use a utility knife and if necessary a hammer to carefully break and remove any caulking or sealant that s binding the old sill to the window frame. Your sill probably isn t this fancy. Gray would look modern.

Scrape away any mess with the edge of the knife. Run a bead of waterproof marine grade adhesive along the old sill. Use cement or waterproof construction glue to attach the gutter to the window ledge then paint the gutter to match the other ledges or paint them all a different matching color to update the house. Fit the narrow tip of a bottle of silicone latex caulk into each crack and overfill it by about inch.

Fill the crack with multi purpose exterior filler. Spread and flatten the caulk with a small putty knife. Finishing the mortar joint. Resist the urge to keep touching and fiddling with the look of the smoothed caulking you will probably make it look worse.

Using a small putty knife starting at the window smooth the caulking flush to the sill. Use the crow bar or chisel to slowly pry the windowsill off the window. However you should be able to purchase grey exterior filler which will be a close match to the concrete. You may also need to pry away trim material known as side casing.

Remove the excess material build up on the putty knife. Keep the sill in one piece so you can use it as a model when cutting the new sill. Drill pilot holes every 16 inches or so through the new sill s front and back edges. Repairing a concrete window sill could appear to be a major job that s far beyond the skills of the average diyer but with the proper knowledge tools material and preparation you might find it s worth considering having a go yourself unless a complete rebuild is necessary.

If the sill is painted repaint the whole sill as this will give an overall better finish. If the sill is plain concrete it will not need to be painted.