How to Apply Hardie Panels on an Exterior Surface

Prepare the OSB or plywood paneling that is already installed with a moisture barrier for the installation of the paneling. Tar-based felt paper is the most common method. Roll out the paper across the width of the wall, cut it with a utility knife and staple it to the wall along the bottom section with a hammer tacker. Place subsequent rows on top of the rows below, covering the entire wall so that each upper piece overlaps the lower by at least 2 inches.

Install a row of paneling across the bottom of your installation surface. Leave 2 inches of space between the first row of planking and the ground or deck surface you are working your way up from. Ensure that there is a space of at least an eighth of an inch between each plank along the vertical joints and install the panels so that the vertical sections overlap the wall studs beneath the OSB or plywood paneling. Two panels should share the same vertical stud line.

Fasten the panels onto the wall with the nail gun. Sink the nails into the panel no less than three eighths of an inch from the vertical edge, and space the nails out every few inches. Leave at least 2 inches near the corners, as you will crack the panel if you try to sink a nail too close to the corners of the panels.

Place a row of Z flashing on top of the first section of panels. Attach the flashing to the wall with nails so that it covers the top edge of the paneling and overhangs down slightly over the face. Leave at least a quarter of an inch gap between the next row of panels that are installed on top of the first row of panels. Repeat the entire process for each subsequent row as you work your way up.

Caulk the vertical joints between the boards after you have finished the installation. Do not caulk the horizontal joints where the flashing is installed, as this will keep moisture from draining away from the wall via the flashing.