Hardibacker

the james hardie co was founded in 1888,started making cement backerboard in the 1980's.it is the best product on the market today,very easy to use.i have years of experence with there products,and i find them to be the very best...cement backer board is not waterproof,but water cant hurt it,even when soaked in water for months or even years.........

I know that cement board is not water proof and is not damaged by water but what about the hardibacker? The hardibacker seems to be some kind of fiber board. The broken piece had fibers in it and I was wondering if this is the reason it stayed wet for so long?

hardibacker is a cement board,the fibers are fiberglass,the board is so dense due to compression,which tends to hold water.
don't forget it's not the backerboard's job to stop water,but to allow water to pass through it,if it did not the mortar would not dry,....good luck

The fibers in the board are fiberglass-like fibers, which are not absorbant. They are also sometimes added to concrete to make it more resilient to developing small cracks while curing. They are only an asset to the board, not a detriment.

As for your "water test" of the hardibacker, that is irrelevant. Water and mositure is supposed to pass through it, as opposed to repel it. (That is why thinset mortar adheres to it instead of just slipping off of it; it draws the thinset into it for a better bond.) The TILE and grout are supposed to stop the water before it gets to the backerboard. Moreover, wetting the back of a tile will yield similar results. If the Hardibacker became brittle when wet, then that would be a disadvantage, but, as you might have noticed, it does not, which is another one of its assets.

The backerboard is there to support the tile so that individual tiles set together as one unit once the thinset cures. Hardibacker does not shread like cement board under pressure or jolts, but it adheres to thinset just as well. That is why it is reputed to be better than cement board and often is the preferred backerboard. The primary (and perhaps only) significant advantage to ordinary cement board/wonderboard is that you can score and break it with a utility knife, whereas you should use a circular saw to cut Hardibacker.

DEAR BOB, (KINDLY RESPOND JUST AS SOON AS POSSIBLE ... TIME IS OF THE ESSENCE!)

I have read the following: "Cement board is not waterproof ... water can wick right through it. And what's on the other side of the cement board? Your house's wood framing.

You'll find manufacturers telling you about their specific product, but they can't say how their product will interact with or protect materials attached to it.

So cement board is essentially not affected by moisture.

Your house's wood framing will be affected by moisture.

Insulation can be affected by moisture."

I AM VERY SENSITIVE TO MOLD, AND I AM CONCERNED THAT IF A WATERPROOF MEMBRANE, SUCH AS REDGARD, IS NOT APPLIED TO THE HARDIBACKER WALLS OF MY SHOWER, (AND ON THE HARDIBACKER WALLS OF MY TUB/SHOWER SURROUND), THAT MY WOOD FRAMING WILL BE (AND MY INSULATION CAN BE) AFFECTED BY MOLD, NOT TO MENTION THAT "UNTREATED MOISTURE DAMAGE CAN ULTIMATELY CAUSE EXPENSIVE STRUCTURAL DAMAGE TO WOOD STUDS AND SUPPORT BEAMS." REGARDING THE HARDIBACKER, THE PERSON TILING MY SHOWER AND TUB/SHOWER SURROUND THINKS IT'S SUFFICIENT TO APPLY REDGARD TO THE SEAMS, PENETRATIONS, AND CORNERS WHERE TWO PLANES MEET. SINCE WE ARE TILING WITH LARGE (AND SOMEWHAT HEAVY) VERTICAL PANELS, SHE IS ALSO OF THE OPINION THAT THE TILE WILL HAVE A STRONGER ADHESION TO THE HARDIBACKER THAN TO A [SOLID] REDGARD MEMBRANE. HELP, I'M VERY CONCERNED AND REALLY NEED SOME GOOD ADVICE JUST AS SOON AS POSSIBLE, AS MY TILE PERSON IS RARING TO MOVE FORWARD. MANY THANKS, JOANNE