The inspector suggested that these are easy fixes but most of the searches for repairing window sills brings up rotten wood and that's not what I've got here.

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and also this one

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I find that a urethane caulk works wonders in cases like this. It bonds like no other caulk I've used, can be had in a huge variety of custom colors, doesn't shrink much, remains very flexible, and is paintable. I'm most familiar with OSI Quad.

Be warned, it's extremely sticky--you won't get it off your clothes, and you'll have to wear it off your skin. It cures very slowly, so don't expect it to be skinned over after a few minutes like silicone or latex.

Cut a small opening on the tube and press firmly to inject the caulk deeply into the crack. Use cardboard or a plastic scraper to remove any excess, pressing very firmly to slice the extra caulk off the surface rather than smearing it wide. Ideally you'll be able to apply and tool the caulk in one pass with the tube nozzle, though.

  • Good advice. For the larger horizontal cracks, a self-leveling polyurethane masonry sealer (e.g. lowes.com/pd_332520-286-866031_0__?productId=3231696) may be a bit easier to use, as it will flow into the horizontal cracks. You may still want to tool it a bit for appearance. Something like OSI Quad is more general purpose and probably the best bet if you only need one tube. – Shimon Rura Apr 21 '16 at 17:59

Backfill with fixall in the deeper spots and smooth over with a epoxy sealer. Or, do the whole thing with dex-o-tex.. stuff is magic i think you could fix my 40 year soured marriage with it.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. – Daniel Griscom Oct 22 '19 at 12:02

Polyurethane caulking works but you will find that sometimes you see that through paint.

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