Hardi Backer Requirements

So I have tiled a few times and read the requirements for Hardie Backer underlayment and followed those very carefully.

I happen to be at a draw inspection the other day and noticed that the contractor was using roofing nails to secure the hardie backer in 2 upstairs bathrooms. I question him (not part of a draw inspection) and he told me that it was his way of doing it and that its OK.

I say BS.

Do any of you know any instructions that say that it is ok to install the hardie backer that way?

From Hardie.

• Minimum 7/8” long galvanized or polymer-coated 18-gauge chisel point staples with 1/4”crown.
• Minimum 7/8” long galvanized ring shanked underlayment flooring nails

And this is for flooring? My research, manufacturer requirements for warranty and from experience says use screws.

I am not a tile guy but have done it and always used screws for the couple times that I have done it.

This is on a raised foundation.

Here you go. Link to the Hardie Backer Installation Guide

Thanks for the info. I would say that screws are the best rout. Read the fine print and you will understand what I am talking about.

Last time I did this I really hated the screw part…blisters for days!!! LOL

The thin set or mortar under the hardie is doing the majority of the work. I use screws as well. No issue with the right type and the correct driver.

Interesting when you go to the Hardie site, they have an FAQ page. Check the answer regarding what type of fastener to use… :roll:


And the next question. What if the screws don’t set flush?

Use the right driver and there is no problem. And besides, there would be thin set on top of the screw anyway that would level out the small amount of head that is not sunk.

I agree, that’s how I do it. I was just pointing out that one of the answers is to use roofing nails. Which in my opinion would be harder and take more time.

Agree. But then if you already have a roofing nail gun…:wink:

If you use the correct backer board screws, they undercut the material creating a self drilling countersink. Contractors only use roofing nails because they are cheaper, which doesn’t say much for the installer.

Thanks for the input.

Back when I tiled my master bath the hardi backer came with a brochure with instructions that specifically required using a special screw which I did. After reading the new version of instructions I have learned that using the specified roofing nails would also be an acceptable method of fastening.

I think I will take the extra time and use screws as I have not had any issues with my last tile project.

And next time I see someone installing with roofing nails I will just keep quiet.

Thanks again.

The thin set under the hardiboard is intended to fill in the voids so the tiles will not pop off later due to flex in the boards over voids. It is not intended to adhere the boards that’s what the fasteners are for.

What about the joints, I bet they didn’t grout and tape them before setting the tile

I have used the nails method many times and never had an issue. Must use proper thinset and nailing pattern. Much faster with a nail gun than screws. Do a few thousand square ft and it saves a ton of time. If its a small area, I use screws so I don’t have to load compressor. I have also pulled up a couple of floors that were installed with just nails or screws and no thinset due to cracked tiles.