I have been through this myself and I also have spoken with several people about this that have 30 years plus in the dogs. I over think things all the time especially with my dogs. Best thing to use is dirt, lol. I have used sand, which is not IMO, depends on climate I guess but it does make things harder when you have problems like fleas or ringworms. Decking is over doing but each is own I guess. Buy pretreated wood and don't seal it, the pretreated wood should last 15 -20 years in area like that because of shade is needed for a kennel that area should be covered anyways, long as it is not getting constant direct sunlight it will last. I also spent several years as a professional painter, I know wood for sure. One thing that did work but was slightly exspensive I thought was the smooth river rock, pretty easy to clean the area and acted as a decent filter. I use just plain dirt and I take the old cedar shavings from the houses and dump them on the floor of the kennel. If it rains really bad I will buy a bag of pine shavings as they are 2 bucks cheaper than cedar and spread them out. I rake out the kennels every couple of months and start over. Far as a cleaner, nice and easy formula a flower waterer, bleach and water mixture once a month or two and you are good to go no urine smell, cheap, and you kill all kinds of bacteria. Good luck.
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