I am a flood and water disaster management paraprofessional. In my experience the best defense for flooding in your basement or crawl space begins with your gutters, get the water three or four feet away from your house so that any standing water is at least three or four feet away. The next line of defense is the grading around your house make sure that you have 3 or 4 inches of fall in the soil around your house so that there is no standing water three or four feet around your house. Do not be fooled by your landscape mulch or rock if the soil underneath falls back to the house seawater will also it needs to be backfilled. This usually alleviates most problems keeping water from getting to the foundation itself. If you have an east or south facing gable so that rain can blow against the house bypassing gutters you may want to put plastic under your landscaping to keep that three or four foot barrier around your house dry on top of the backfill. I do agree with the comment previously there any cracks in the foundation need to be filled to avoid getting moisture in the crawl space. With that said I categorically refute opening the foundation vents " Ever ". Because in the summer when it's hot and humid the humidity outside is drawn into the cooler crawlspace and then condensates on all the metal piping water lines, air conditioning, gas lines causing moisture in crawl space that over time can lead to mold growth and wrought. When we do repair and clean up we usually cover over the vents with plastic running down the foundation wall starting at the floor joist and then covering all the dirt to avoid moisture coming up from the ground turning the crawl space into a semi conditioned space. In the winter months the heat will naturally dry it out and it will stay dry as long as moisture does not get inside the crawl space, and you can maintain that semi conditioned space. Then you will not need to call someone in such as myself to repair damages :-).
I am a flood and water disaster management paraprofessional. In my experience the best defense for flooding in your basement or crawl space begins with your gutters, get the water three or four feet away from your house so that any standing water is at least three or four feet away. The next line of defense is the grading around your house make sure that you have 3 or 4 inches of fall in the soil around your house so that there is no standing water three or four feet around your house. Do not be fooled by your landscape mulch or rock if the soil underneath falls back to the house seawater will also it needs to be backfilled. This usually alleviates most problems keeping water from getting to the foundation itself. If you have an east or south facing gable so that rain can blow against the house bypassing gutters you may want to put plastic under your landscaping to keep that three or four foot barrier around your house dry on top of the backfill. I do agree with the comment previously there any cracks in the foundation need to be filled to avoid getting moisture in the crawl space. With that said I categorically refute opening the foundation vents " Ever ". Because in the summer when it's hot and humid the humidity outside is drawn into the cooler crawlspace and then condensates on all the metal piping water lines, air conditioning, gas lines causing moisture in crawl space that over time can lead to mold growth and wrought. When we do repair and clean up we usually cover over the vents with plastic running down the foundation wall starting at the floor joist and then covering all the dirt to avoid moisture coming up from the ground turning the crawl space into a semi conditioned space. In the winter months the heat will naturally dry it out and it will stay dry as long as moisture does not get inside the crawl space, and you can maintain that semi conditioned space. Then you will not need to call someone in such as myself to repair damages :-).