Introduction: How to Lay Fiber Rock or Hardy Backer and Get Ready to Lay a Tile Floor.

Picture of How to Lay Fiber Rock or Hardy Backer and Get Ready to Lay a Tile Floor.

How to lay Fiber Rock or Hardy Backer........... some call it cement board.

The first thing is to remove all old tile, particle board, laminate, just take it to the bare subfloor. Making sure to remove all loose particles, wood, dirt, staples. I like to both sweep and vacuum, and make sure to check floor for all loose nails. Take a hammer and tap them back in tight. You are now ready to start installing Fiber Rock.

Step 1:

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Fiber Rock comes in 3 x 5 foot sheets. You will need to cut it to fit around corners, fireplaces, anything that's not in a straight line.

Step 2:

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Make sure each board is tight together, this is important. You want no movement once you lay the tile, because that would cause cracking............. and you don't want that. There are make on the Fiber Rock that direct you where to screw it down. They are about every 8 inches. This secures it, and limits the chance of movement.

Step 3:

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once you have the entire room complete (as in the picture above), it will be time to move on too mud/cement and tile. I will cover that in another instructables.

NOTE: The video attached shows how we layed the floor, step by step, sometimes visual aids make it easier. Hope you floor turns out beautiful.


JoeG22 (author)2017-03-28

Many things wrong with this. If you look at manufacturer's installation instructions you will see that installing cement/fiber backer board directly over plank flooring is not correct. The instructions will also tell you to embed the backer board in thinset, this is to fill voids. Every backer board manufacturer I know also expects you to gap the panels, not butt them tight to each other. Do yourself a favor and go to to get tile install advice from professionals.

Joe, I do not claim to be a professional. And I would always advise someone to seek professional help before starting such a big project. First, what I have came to understand is Fiber Rock does not require anything under a wood sub floor. Mine happens to be 2x6 tongue and grove, and a full 2 inch thick not 1 1/2. If you look in one of the pictures you can see there is small gaps between most of the Fiber Rock. It is hard to tell without standing over it. Last but not least, the professional that is running the project has a green tape, it reminds me of a mesh, and I was told we will fill in all gaps with thin set and tape, but that will happen at tile time. The favor is simple, this is my floor, and I am trying my very best. I do not expect you or anyone else to take my word as Gospel, nor do I hope they do. This is merely my DIY travel, and I would expect everyone to do intense research for their own. Thanks for reading.

JoeG22 (author)its a wood thing 2017-03-29

I wasn't trying to be overly critical. I think it is great wanting to share a project. It is important though to point out where the instructions provided are in error to help others not make the same mistakes.

You may want to read through the installation guide for USG FiberRock (Hardi and other backerboards are similar) because it should not be installed directly over dimensional lumber, whether t & g or not. Plywood or OSB is acceptable. The backerboard panels also must be installed using thinset under the panel. Here are two snippets from the installation guide for USG FiberRock that spells this out quite clearly:

The subfloor
should be APA Span-Rated
Plywood or OSB with an
Exposure 1 classification
or better with tongue and
groove or back blocked at
the unsupported edges.

Panel Application: Apply Type 1 organic adhesive
with 5/32" v-notched trowel,
latex-fortified mortar with
1/4" square-notched trowel.
Comb out adhesive or mortar in
straight, parallel rows (as shown
below) and immediately cover
with panel. Adhere panels to
subfloor, one panel at a time.

Here is the link to the installation guide for USG FiberRock:

About This Instructable




Bio: My name is Ronnie Lees Sutton, and I live in Modesto California. I own a small business that is called ITS A WOOD THING. I ... More »
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