We have a very large patio area that had spalling concrete with lots of crumbling and a huge stain from a hot tub. These deck tiles were the perfect solution. We patched our spalling with concrete repair to prevent further crumbling and power washed the patio before installing. Then we went right over the existing concrete. These tiles should provide excellent drainage. It is beautiful. Instead of an ugly concrete patio we feel like we have a courtyard in a resort! We laid almost 600 ft.² in about five hours. Then in a couple evenings at a couple hours apiece we finished doing edge piece cuts with a 10 inch circular saw, carbide tipped, 60 point blade.We have had them down for two weeks now but so far have not had a rain. I will try to update after they have been installed for a while.