At a lumberyard or a home center, you can buy prejointed planks that are almost as easy to install as 4 x 8 sheet paneling. They come in a variety of woods and finishes and are generally between and inch thick and from 3 to 7 inches wide with tongue-and-groove or shiplap joints. A typical package of mixed widths and lengths will cover 24 feet.
On new framing, use the planks as the basic wall covering. On existing wails, remove base, window, and other trim. Turn off the power to electric outlets and re-move the cover plates. If the walls are even and the planks are to be horizontal, you can nail them to the studs; otherwise, nail them to horizontal furring strips.
To install planks vertically, start by putting the first plank in a corner, with its tongued edge out. Make sure it’s plumb. Using finishing nails, se-cure the plank’s inner edge to each furring strip; predrill holes in hard-wood and sink the nailheads with a nail set. Then angle a nail through the tongued edge going into each strip; sink the nail head slightly. Angle the nails on each subsequent plank and press against the plank for a tight fit. As you work, cut the planks to fit around windows and doors and at wall edges. Use a slip-in template to mark cutouts for electric outlets and a compass to mark uneven cuts along was.
To put up horizontal planks. mark the studs and nail into them. Attach the first plank at floor level with its tongued edge up; level it with shims. Then work up the wall.
Finish by installing matching trim along the floor and ceiling and around windows and doors.