I am laying down 1/4 inch hardie board for tile in a bathroom. A shower will be built as well. My first question is do I cover the entire floor (including the shower area) with backer board, or do I stop where the shower curb or floor will be?

Also, due to some old house weirdness, I could extend the hardie board 2 inches or more under where the drywall will eventually hang. Is there any structural advantage to doing that, or should I just end the hardie board where I know the walls will end up?

1 Answer 1


Typically, you would install the shower curb/pan first, then install your underlayment, concrete backer board in this case, up to it.

As to the floor, we usually extend the concrete board as far as we can under the wall finish, and have a gap between the bottom of the wall finish and the floor finish that gets covered up by the base to mitigate water damage if some water gets under the base.

When we get freaky about it, we paint and sometimes redguard the bottom of the base before installation, then clear silicone caulk the base to the floor after installation. Mostly we do this if there are young kids that are going to be using the bathroom and the clients are ok with the mild funkyness of such an install.


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