Sketch the wainscoting design onto the drywall. Decide the height and width. Sketching it on the wall helps you decide. Suggested measurements are a 1-by-3-inch top horizontal board, ½-inch thick plywood or MDF for battens, 1-by-2-inch boards between battens and a 1-by-4-inch horizontal baseboard. Height can be anything you like, but larger rooms usually look best with around 48-inch height while smaller rooms look better with up to 60-inch heights. A carpenter’s level keeps the lines level, and a carpenter’s square keeps them perpendicular.
Locate and mark the studs in your wall with a stud finder. Battens should be attached over the studs. However, if your studs are too far apart for your liking or if the studs are not regularly spaced, you can add more. Regular spacing is the most important factor.
Cut the wood to size according to your design and measurements. All the pieces must fit together well and leave no gaps once installed on the drywall.
Squeeze a bead of construction adhesive on the top horizontal board’s back and press it into place on the drywall. Use a level to keep it straight. Nail it in place to the wall studs with 2-inch nails. Glue and nail the bottom baseboard in place.
Apply construction adhesive to the back of a batten piece and place it between the top board and baseboard over a wall stud. Nail it into the stud in several places with 2-inch nails. Repeat this procedure for all the battens. If any of your battens are placed over drywall in places without studs, toenail 1-inch nails in the ends of the batten nailing it into the top board and baseboard.
Squeeze construction adhesive on a board piece’s back. Press it to the drywall between the first two battens. Repeat this process for all the other board pieces. Let the glue dry.
Fill nail holes or knotholes with wood filler and let them dry. Sand the entire wainscoting and remove the dust with tack cloth.
Brush or spray on an even primer coat. Let it dry. Brush or spray on a coat of paint. Let it dry, and then apply another coat.