Repair Cracked Concrete Window Sill

Concrete has high compression strength but low resistance to bending tensile strength so the steel reinforcement is necessary.

Repair cracked concrete window sill. Here is the smoothed caulking. Brush the sill with a soft brush to remove dust and dirt before applying the first coat of masonry paint after any of the following work has been done if required of course. Fit the narrow tip of a bottle of silicone latex caulk into each crack and overfill it by about inch. Fix any small or medium cracks in your concrete window sill with caulk.

If you have the pieces just clean off any loose mortar from the block. Remove the excess material build up on the putty knife. Water is sometimes able to penetrate the concrete because of damage to the surface or just deterioration over time. Use mortar mix on the block and replace the pieces.

If the sill is plain concrete it will not need to be painted. Spread and flatten the caulk with a small putty knife. Dust from the sill will rub into the filler making it dirty but also blending it in with the rest of the sill. Scrape away any mess with the edge of the knife.

I have on hand a tube of big stretch caulk and a tub of dap bondex ready mixed concrete patch. I have an exterior concrete window sill that has a crack in it that i want to patch pic attached. Using a small putty knife starting at the window smooth the caulking flush to the sill. Resist the urge to keep touching and fiddling with the look of the smoothed caulking you will probably make it look worse.

If the sill is painted repaint the whole sill as this will give an overall better finish. Any cracks can be sealed with the mortar mix or cement based caulk. Allow to dry completely before applying a second and third coat. However you should be able to purchase grey exterior filler which will be a close match to the concrete.

Finishing the mortar joint. What would be an appropriate material to fill it with.