Joshua: You are correct the deck should be provided with a waterproof membrane. Some of these deck waterproofing materials can be textured to look like tile, others can be covered with a traffic surface such as tile, stone, wood or other materials. Best is to have a deck waterproofing contractor visit the site to examine the existing conditions and provide the various options and costs for you. To locate a local deck waterproofing contractor you may call us at 855-494-5972, or try here: https://porch.com/seattle-wa/contractors. Thank you.