New answers tagged gap
DMoore is right, if you have a grading problem you should get that fixed if you can afford it. That said, in your other comment you mention that its just water blowing in? If the water drains toward the wood normally and you only flood because of wind blowing it in, I would definitely not plug the gap. Get a piece of plastic trim and screw it to the outside ...
I am almost positive that this gap was left there to let water OUT. I would not fill it. If you do want to fill it and potentially cause other issues, just use masonry caulk.
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