Do I Really Need to Mortar Hardie Backer to the Subfloor for Tile Installation?
Asked by NerdyNinja97
I'm in the process of installing tile in my home and have a good amount of experience with tiling on cement foundations, but subfloor installations are new to me. I've come across conflicting advice online and would love to hear any personal experiences, both good and bad. I'm a bit concerned about the weight of the tile adding stress to the flooring system. While it seems easier to just screw down the Hardie backer and lay tile over it, I've seen guidance recommending that I should also mortar the backer board to the subfloor before tiling, just like I'd do with tile. Additionally, how essential is it to tape and mortar the seams of the Hardie backer if I'm covering it with tile, especially since it's not a wet area? Thanks for any input!
Answers
I recently ripped out a 33-year-old bathroom where the main area had a cement board just screwed to the subfloor, no mortar. The toilet area had plywood, and it all held up surprisingly well over the years. Just goes to show that both methods can work, but you might want to consider long-term durability.
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The best advice I can give you is to strictly follow the manufacturer’s instructions. Mortaring the Hardie backer and taping the seams ensures a solid installation and can prevent future problems. You definitely want to ensure everything is secured and ready for the tiles!
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In my past experience, we always mortared and screwed everything as required. Never had an issue with the tile guys complaining about prep work, and removing a piece later was a nightmare! Mortaring really helps fill in inconsistencies, and it makes it all feel rock solid.
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Honestly, if you're skipping the mortar underneath, you're not using the product the way it was intended. Especially with how tile installation works, it needs that layer to stay secure.
NotAProBut: Where do I find those designed instructions? I've seen some alternate methods, especially for bathroom installs.
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I didn't mortar my backer, just followed the recommended screw spacing and it felt super solid. It’s been about eight months now without issues, but I guess time will tell!
JustCurious78: What kind of subfloor did you have? I'm working with 2x12s at 2'OC with 3/4" plywood.
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If you're not mortaring, why take the risk? Sure, you'll save time and effort, but potential catastrophic failures aren't worth it. Be sure to screw down your subfloor first to reduce movement!
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Absolutely, you should set it in thinset! It's the best practice for a solid install. Without that extra layer, you risk issues down the line.
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CraftyBuilder44: I like that you're sticking to the guidelines! That’s how you do it right.
CuriousHandyman88: I'm definitely gonna look up the manufacturer’s instructions for Hardie backer.