If properly waterproofed/installed, will extreme temperatures still gradually warp cement backer boards and crack tile flooring? Thank you.
Ya don't need backer board for tile floors. A good coat of floor leveling mix (definitely not self-levelling whatever the name says) and a good mortar base with 1/4 trowel will work just fine. But durok is a cement product so it would only distort due to expansion and contraction which proper installation would minimize.
Nope. Not if it's installed properly on a solid foundation.
As in all construction, look first at the base from which you start the work. If the base on which they are installed is solid/secure, and you follow your own suggestion of PROPER installation, they will not warp at all.
If you are above grade and can't lay the tile over a smooth and level concrete surface, the cement board over a very stiff frame that is properly attached to a foundation or footing below the frost line should be fine. The challenge with an outdoor tile floor is to get the grout sealed properly and maintained so as to prevent moisture from making it in during rains.
Concrete backer boards are not waterproof and will wick water. In outdoor applications tile should be stuck to concrete, not a cellulose and concrete mixture. Even with a polymer modified thinset and grout you cannot be certain of a 100% waterproof exterior tile floor over backerboard. When the manufacturer tells you it's not recommended.....listen to them. Nothing worse than a failed tile floor.
