Floor tiles should be nonporous. This is actually a no-brainer but there is a vast range of porosity from porous to nonporous. Very few tiles are truly nonporous. Most floor tiles are porous to an extent. Of course you would find tiles allow the passage of water like a sieve or a sponge but it will absorb moisture to an extent. This extent to which a tile will absorb moisture is determined by the number of air holes present in the tile. This is partly influenced by composition of a tile and the mineral density. It is partly determined by the treatment that a tile is subjected to. Many common tiles are porous, albeit they appear hard and a complete solid with no air holes, gaps, cracks or leaks.
There are four classifications of floor tiles on the basis of their porosity. You must find out this classification before you even consider a particular tile for your home, office, commercial space or any other installation. You should be more careful when you are choosing floor tiles for bathrooms, utility areas, kitchens and any other space where you would be using water or the floor will get exposed to moisture, including precipitation which is unavoidable for outdoor installations.
• The most porous floor tiles are impervious. They have a 0.5% or less water absorption rate. They are perfect for kitchens, bathrooms and utility areas. You can install impervious tiles outside, on decks, by the pools and driveways. However, the material you choose should be appropriate for an outdoor installation. Multiple materials can claim the tag of being impervious.
• The second best option is vitreous tiles. Vitreous floor tiles have a water absorption rate of between 0.5% and 3%. You can choose these tiles for your living room. Although a living room is not exposed to water or moisture to the extent a bathroom, utility area or kitchen has to endure, it is still vulnerable to spills.
• Semi vitreous is the third classification. It is so rated for its water absorption capacity of 3% to 7%. Such tiles can be installed in bedrooms and other areas where there is very little chance of spillage or exposure to water.
• The fourth classification is non vitreous. Such tiles allow over 7% water absorption. These tiles are not appropriate for floors. These are often unsuitable as wall tiles as well since dados and backsplashes have to deal with moisture.