Wainscoting is panelling that runs along the bottom half of a wall, underneath a strip of decorative moulding known as a chair rail. MDF is a wood composite product made of very fine dust in a specialised chemical bonder that creates a panel of high consistency in texture and thickness. The panelling can be formed in two layers, with a backer panel and a decorative layer.
Cut your 48-by-96-inch sheets of 1/2-inch-thick MDF into three equal 32-by-48-inch panels. Cut one sheet for every 12 feet of wainscoting. Cut the 3/4-inch-thick MDF in the same quantities. Use a table saw with a fine-tooth blade.
Draw a 42-by-22-inch rectangle in the centre of each 32-by-48-inch panel of 3/4-inch-thick MDF, using a jigsaw. Cut one inch from each edge of the 42-by-22-inch panels, to make them 40 by 20 inches, using the table saw.
Install an ogee bit with a 3/4-inch-wide cut, and a bearing into your router. Set the depth so that the bearing rides 3/8 inch below the base plate of the router. Start the router and run it along the outside edge of each of the rectangular panels. Start the router and run from left to right.
Run the router around the inside of the cutout in the 32-by-48-inch panels. Apply wood glue to the back of these panels and set one on each 1/2-inch panel, with all edges flush. Nail the panels together with 1 1/4-inch pin nails, one every 6 inches.
Apply glue to the back of the cutout panels you routed and fit one, centred, into each panel. Nail them in place in the same way.
Depress the buttons and drag the stud finder over the installation wall marking each spot where the finder lights up and beeps, to mark the studs.
Fit the panels against the wall, starting at one end. Stand the panel against the wall and drive one 3-inch treated deck screw through the panel 2 inches down from the top of the panel, and one 2 inches up from the bottom, into each stud, with a cordless drill, until the screw heads are just slightly inset.
Fit the next panel butted up to the first and screw it in place in the same way. Continue adding full panels as far as possible. Measure the distance from the end of the last panel to the end of the wall. Divide the remaining distance by two.
Cut a piece the size of the divided dimension from each 32-inch side of a completed panel, so that the middle is cut out, on the table saw and fit the two sections together, to fill the area, creating a complete, small panel.
Nail a piece of 2 1/2-inch-wide chair rail, with the top edge even with the top of the panels. Use one 2 inch nail every 8 inches. Add full length pieces of moulding as far as possible. Measure and cut a piece to fit from the last full piece to the end of the wall, using a mitre saw.
Do the same with 4-inch-tall baseboard along the bottom of the panels. Fit it against the floor, nail it in place with one nail every 8 inches and cut a piece to fit at the end of the wall.