I would like to waterproof the tile floor in the bathroom of a 50 year old home. This is to prevent any additional waterdamage to the subfloor/floor joists. I tried several applications of sealant product but water still leaks through to the crawl space. I installed a shower door but the tenants seem to be unable to prevent water from getting on the floor when exiting the shower. Are there any other products that I could apply?