Greenboard vs Durock

“I like to use Greenboard because it is water proof”.  I hear this all the time.  Greenboard, also known as Aquabloc is not “water proof”, it is merely “water resistant”.  Home owners and contractors make this mistake all the time.  Let’s take a look at both products. 

Greenboard’s composition is the exact same as drywall.  They both come in 4’x8’ boards.  The center of both boards is gypsum.  Gypsum is porous.  The difference with Greenboard is the green “water resistant” paper covering it.  If the paper on the Greenboard is cut, it will allow water to penetrate the board thus causing mildew.  I find it to be inadequate for any flooring or wall tile applications.  Yet contractors and home owners use it for it’s ease of cutting and cost.  During demolitions of bathrooms I have encountered Greenboard that was wet, moldy and certainly not durable once it gets wet. 

Durock or Wonderboard is a mold resistant and water-durable panel.  It truly is!  I have performed demolition on many bathrooms and have never seen durock moldy or damaged.  Durock may be harder to cut, heavier and a few dollars more but is a more durable and “water resistant” than greenboard. 

So the next time you see your contractor using Greenboard ask him what the difference is and see what he says.  If you have a choice, always go with the better product.  In a bathroom, it will make much more of a difference. 

I have used it also in damp basements.  I would cut a piece of Durock 5” high (or higher if there is a history of high water levels in a basement) and fasten it to the bottom of the wall and then start my blueboard on top of the durock.  (Durock can be plastered with a product called Weldabond.)  After it is plaster I would add my baseboard as normal.  If you ever get water after in your basement, the most you would have to remove it the baseboard.

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