Originally Posted By: ecrofutt
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See following extracted from www.hometime.com
Where the tile is installed by a good tile guy, I don't usually see problems in the first several years.
Where the tile is installed by a non-professional who really is very good at it, I see problems frequently.
Primarily due to the deterioration of the grout and the subsequent wetting of the greenboard.
It is not a question of IF the greenboard will get wet and swell, its a question of how long will it be before it does.
Concrete backerboard won't suffer like greenboard when it gets wet.
Its a question of do it cheap or do it right.
Moisture-resistant drywall, or "greenboard" as it's often called, is made out of the same gypsum core as drywall. The only difference is that it has a moisture-resistant facing.
Greenboard is sometimes used as an underlayment in wet areas such as a bathtub surround or shower. It's installed the same way as standard drywall.
Keep in mind that greenboard is not water-proof. And if your tile is not sealed properly the greenboard may deteriorate from moisture penetration.
Concrete backerboard has a solid concrete core and is faced on both sides with fiberglass. It's an ideal underlayment for wet areas like shower walls and bathtub surrounds
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