Fix Cracked Window Sill

Scrape away any mess with the edge of the knife.

Fix cracked window sill.

A split cracked or simply weathered window sill can detract from an otherwise beautiful window. Step 1 use a putty knife or a paint scraper to remove the peeling and cracked paint. Then we used a hammer and banged popped the sill upwards being careful to avoid any further damage. The sill or lower horizontal wood plate extends into the room creating a target for impacts and other damaging factors.

With any luck this re work may keep the crack closed up. We pulled out the rest of the nails that were left behind. Check for sill movement such as a crack where one side has settled or is down farther than the other side causing a crown and a crack. Switch to a 220 grit sanding sponge to finish off with a very smooth surface.

Step 1 fix any small or medium cracks in your concrete window sill with caulk. Repairing weathered sill finishes is simply a matter of sanding and repainting. Other sill repairs can extend from basic maintenance to reconstruction of the sill. It is possible to fill in quite sizeable holes with the masonry filler method but if the edges are crumbling away you ll need to build moulds to shape the sill correctly a job that s probably beyond most diyers skill level.

You will need to raise one side or the other with plastic. Repairing window sill damage is typically simple. Once it is ready you can apply it to the surfaces that require stabilization and repair. Sometimes a skirting trim or board is installed under a sill like this to help support the sill.

Spread and flatten the caulk with a small putty knife. Chip says apply painter s tape around the edges of each crack. See below for tools and a shoppin. Do this before trying to fill the crack with any kind of filler.

If there is not one there you may want to push up the cracked sill and install a skirting board to help support the sill. Caulk tube versions are easiest to use just squeeze the sealer into the crack then smooth it with a plastic spatula or putty knife and peel off the tape. Fill thin fissures 1 8 inch to 1 4 inch wide with a concrete patch sealer. This old house general contractor tom silva shares some tricks of the trade for installing a new long lasting windowsill.

I prefer using a glue brush to help the epoxy work down into cracks and crevices. First we ran a cutting blade this is my favorite caulk removing tool around all the edges including between the underneath trim and the window sill.