Home>Discussions>PLUMBING>Proper Installation of Hardie Backer Board
4 posts / 0 new
Last post
Proper Installation of Hardie Backer Board

Getting ready to install new backer board around the tub and hang new tile. We have seen conflicting opinions on how to properly install the backer board. Some say rest it on the lip of the tub, some say to take it over the lip to within 1/4 inch of the tub itself. Which way is the right way? We don't want a wicking problem. Thanks for your help!

Re: Proper Installation of Hardie Backer Board

Wall Installation

Ensure framing is structurally sound
Must comply with local building codes and ANSI A108.11.
Use a minimum of 2" x 4" wood studs or 20-gauge metal studs, which must be straight, properly aligned and spaced a maximum of 16" on center.
In tub and shower enclosures, ensure that the framing is adequately reinforced at the corners.

Determine layout of HardieBacker® cement board
Boards may be installed vertically or horizontally.

Edges of the board parallel to framing must be supported by a structural framing member.

Score and snap boards to required sizes and make necessary cutouts.

Attach HardieBacker® cement board to framing
See applicable building codes regarding vapor barrier requirements.

Install boards 1/4" above floor, tub or shower pan and caulk accordingly.
Fasten cement board with specified nails or screws (as listed in "Materials Required") a maximum of 8" on center at all supports.

Keep fasteners 3/8" from board edges and 2" in from sheet corners.

Set fastener heads flush with the surface, without overdriving.

Tape joints prior to tiling
Fill all joints with mortar (see "Materials Required").

Embed 2" wide high-strength alkali-resistant glass fiber tape in the mortar and


Re: Proper Installation of Hardie Backer Board

To answer your question, I rest the board on the tub lip, then seal the gap before tiling.

Don't forget the tar paper under the cement board.

Re: Proper Installation of Hardie Backer Board

Thanks guys! Still conflicting opinions, but I appreciate your help.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.