Tongue and groove is an installation system in which wood planks are held together at the sides by milling that fits together. A tongue fits into a groove. It's generally used for floors, but the system can be used for any surface that's going to be covered with planking, including ceilings. Ceiling boards also generally are longer than floorboards. They will span the whole length of the area and weigh less.
Things You'll Need
Electronic stud finder
Tongue and groove wooden ceiling boards
Small nail gun
Mark all joists in the ceiling after locating them with an electronic stud finder using a level and pencil.
Measure the ceiling's length from one edge to the other while running perpendicular to the joists. Transfer this measurement to a tongue and groove wooden ceiling board.
Cut the board straight across the measured length using a miter saw.
Hold the board to the ceiling, at the starting edge, with the groove of the board facing the wall and sitting 3/8ths of an inch from it. This leaves room for wood expansion. Secure the board with nails, shot up with a small nail gun through the board's face into each joist. Shoot two nails for each joist.
Cut the next board to size to fit alongside the first. Set the groove of the next board over the tongue of the first. Set the nail gun's nozzle on the outer edge of the board, just above the tongue, and shoot one nail up into it at the first joist. Do the same for each point where the board crosses a joist.
Repeat for each ceiling board, nailing them from the sides so that the nail heads are hidden by the next board. Continue until the ceiling is covered. Cut the final board length to fit against a far wall allowing 3/8ths of an inch space there.