How to Install HardiBacker on a Framed Wall

Verify that the supporting wall is framed correctly with level horizontal and vertical surfaces. The framing must meet all local building codes, which are generally based on the International Residential Code. Chapter 6 of the IRC specifies the required regulations for wall design and construction, load standards and required bracing.

Measure the area that you want to cover with HardiBacker then cut out one or more sheets to fit the area. Because cutting can generate a lot of dust, put on a face mask and goggles and work in a well-ventilated area. For shorter cuts, score the board with a carbide-tipped utility knife and a straightedge. For longer cuts use a circular saw. Cut out any areas for plumbing or electrical work. Leave room for expansion joints every 12 feet on center and at all inside and outside corners.

Attach any vapor barriers as specified by local building codes, which can vary by room, location and exposure to moisture. For example, many codes specify the use of such barriers in shower areas. Requirements for interior coverings are generally described in Chapter 7 of the IRC, and those for plumbing are in Chapter 27. Vapor barriers retard or prevent the penetration of moisture into the wood frame. Typical types include thin membranes, such as fiberglass roll insulation or polyethylene, and thicker materials, like rigid foam insulation, reinforced plastic and aluminum. Thinner types are more common for residential use and are usually attached to wall frames with a staple gun or nail tacker.

Mount the HardiBacker to the wall frame at least 1/4-inch above any floor, tub or horizontal surfaces and apply caulk as needed. You can use either nails or screws as long as they resist corrosion and are at least 1-1/4 inches in length. Apply fasteners at every dot marked on the sheet at a maximum of 8 inches on center with all supports. Fasteners must be flush with the surface and at least 1/3-inch from the edges and 2 inches from the corners.

Prepare some of the mortar that you will use to apply the tile. Use this mortar to fill the joints between the HardiBacker. Apply 2-inch-wide reinforcing tape over the joints and mortar. The tape prevents sheet movement that may displace or crack titles along the seam. Allow the mortar to dry before applying the tile.