To install Durock cement boards, first check that the surface is flat to ensure a neat and level installation. Apply organic adhesive and latex-fortified mortar to the surface. While the adhesive and mortar are still wet, add the boards, fitting the ends and edges of them so they lay closely to one another without being forced together. Stagger the joints so that the corners of the cement boards never meet.
If laying on an existing floor or counter that has joists, stagger the cement boards so the joists never overlap. Use a 1/4-inch square-notched trowel to apply the latex-fortified mortar. After applying the mortar, comb it out smoothly in straight parallel rows.
Lay the boards so that there is an empty space several inches around the edges. Install fasteners around the perimeter of the area. To add a wooden border, measure and cut the lumber before attaching to the area with galvanized nails.
Fill any remaining empty spaces in the area or between boards with latex-fortified mortar, wiping any excess from the surface. After filling these spaces, immediately embed mesh joint tape. Allow the floor, counter or surface several hours to dry before installing any tiling or flooring on the cement boards.