Using Hardybacker

[muddog16]

My wife is thinking of redoing the tile in the kitchen and the sales guy told her to use "hardybacker" as underlayment.  So I was sitting around doing nothing (which I do very well) and decided to read her information sheet the salesman gave her!   After reading about the uses and installation instructions a light went off..........1st there was the affect moisture had on the board virtually none, its 90% portland cement!  2nd. Was the zero moldblock technology!   Two good reasons to think about using it in the bus instead of plywood!  Then I read the information sheet and see that a 1/2" x 4' x 8' sheet of hardybacker weighs 2.6 lbs psqft (83lbs) not being sure how much plywood weighed per the same size I googled that and it came back somewhere in the area of between 40 to 60 lbs psqft.  That's a increas of 23 lbs per sheet!.......not that much of an increase!  

After these last 5 years of reading and watching buses being converted and some of the problems we are exposed to, moisture and plywood don't get along very well over time......especially along the floor outer edges and the wall bases!  

http://www.jameshardie.com/homeowner/

This leads me to ask the following question has anyone used Hardybacker instead of plywood in their conversion?   If so what are your impressions good or bad?   I'd like to say "lets see how this goes over" but I know where that leads and I won't ask it!!!!!!!!   As always feedback is appreciated but not always followed............LOL have a great day!

[robertglines1]

6 years ago we put granite over plywood used silicon caulk (for adhesive) so far so good . Had to remove a bad tile (another story) it took a hammer and flooring chisel ;came up in hundreds of pieces. No problems yet but its only been 6 years...

[gumpy]

I did not use it INSTEAD of plywood, but I used it extensively throughout my coach for my radiant heating system. I have 1/2" on the floor, and 1/4" on the walls up to the windows.

My impression of your questions is that I would not want to use it on a span that is not supported below by plywood. Hardyboard does not have the strength of plywood and any expanse will tend to flex and break unless supported. In my installation on the floor, I have 5/8" plywood strips secured to 2x2" sleepers. The PEX runs between the 5/8" plywood strips. I overlaid that with aluminum sheet, and then the hardyboard directly over that. I secured it with the recommended screws that drill a counter sink into the 5/8" plywood.

Another observation is that it's somewhat brittle. If you try to put a screw too close to the edge, it will break. The recommend distance for fasteners is something like 6-8 inches throughout the entire field.

I also used 1/2" in my shower. I mortared and screwed it to 3/4" birch plywood. It made a wall that is like steel! No flex whatsoever. Very stable for tile.

The downside with my usage is the added weight.  

So, to answer your question directly... I would not consider or recommend replacing plywood with Hardybacker.  I would not hesitate to use it for it's intended purpose and installation, though.

craig

[robertglines1]

I should have read closer,pre uses to layers of plywood with a sheet of black material between(lead).Take a piece of hardybacker and drop it on the floor(test) or span you floor joist area and step on it..The little experience I had with it seems it should be placed on a solid surface like gumpy did.Hope this helps..

[Melbo]

I used hardibacker in my shower and tiled over it -- I have somewhere over 30 thousand miles and no cracks or problems.  I went with the hardibacker instead of durock because of the motion of the coach.

I cut the floor into four triangles and set it into thinset mortar with about a half inch of rise to the edge of the shower --- my shower is 36 by 52 inches -- I also used epoxy grout (practice with that first) the walls are attached directly to metal studs which I cut down to be 2 inches  instead of 3 1/2.  I don't remember if I installed them 12 inches on center of the standard 16.

In my opinion the hardibacker would be superior to durock with the motion of the bus for being tiled over in wet conditions but for my counter top I used a double layer of OSB and have had no problem with it.

Once again this is just an opinion and my experiences

YMMV

Melbo

[Ray D]

Yes, it should have support between the backer board and the cabinets. The best is to use 1x4 pine or fir with a 3/4" space between the boards.  It will not warp, swell or delaminate like plywood.  If you use plywood, cut random slots in it to prevent warpage with you're skill saw.  Oh, and don't forget to put thinset between the backer board and your'e wood support.

Ray D

[zubzub]

I don't get what the big deal is with hardibaker.  For years I have been using cement board for tiles surrounds, backsplashes and shower stalls.  The product is strong, requires less screws per sq ft than HB.  I have yet to be convinced as to why I should use HB which is more expensive than CB.

[Melbo]

Zub

I typically use durock or cement board in houses etc but with the movement of the bus I used the hardibacker. The price was about the same as the concrete board. I find it a little harder to work with and as mentioned they like lots of screws in it.

I may have had the same experience with the concrete board but for the little extra hassle and not wanting to do it again ( there are many projects on the bus I have done two three even four times) I went with the hardibacker for the shower. Like I posted I did not use it for the kitchen counter because of the lack of moisture just the shower.

Melbo

[Skykingrob]

Pat
I am not sure how you are going to use the product but if you are going to lay tile on it, then consider a new product called "wedi". It is product that has portland cement on each side with closed cell foam sandwiched in between. So you get the tile adhering substrate of portland cement and insulation in between. It wieghts just 18 pounds for a 4X5 sheet ($28 per sheet) compared to the other products. It is not structural so you can't use it like plywood or durock/cement board but with the closed cell foam, you get some cushion and according to our local tile shop is designed for applications where there is some movement. I put it through the kitchen bath area of our conversion before laying marble on it. You mortar it down then screw it every 12 inches with special washers.

Rob
91 LeMirage XL
Missouri