Ensure new wall is square with opposite wall by measuring even lines. Draw a line straight down from the ceiling to the floor. Make a chalk line at the top of the ceiling for the top plate. These lines keep the top and bottom plate parallel. Attach top plate to ceiling using screws. Make sure the screws are lined up with the ceiling joists which are usually 16 inches apart. Attach the bottom plate to the floor.
Attach a 2x4 to both ends of top and bottom plates. From there, measure out every 16 inches along the top and bottom plate for the vertical studs. Using a framing square, draw the 2x4 stud locations. If installing a wall around a fireplace, take into account where ceiling to floor studs are not needed. Tap studs into place, nail studs into base plates at an angle.
In this project, we built a solid floating mantel right into the wall. Teeth that fit between the studs are then attached to the back of the mantel. Draw lines on the back of the mantel where the teeth will attach. Temporarily attach teeth with one or two screws to the back of the mantel. Pre-drill two holes into the mantel and into the teeth, these are for the lag screws. Insert 8” lag screws with washers to attach the teeth to the mantel. Tap mantel into place. Screw teeth into studs. Cover mantel with plastic to protect it during drywall installation and painting.
Make notes of any obstructions like electrical boxes or lights where you’ll need holes cut into the drywall. Measure these obstructions from the studs and transfer the measurements to the drywall and mark them with a pencil. Drill a starter hole in the drywall and then cut around these measurements with the keyhole saw. Screw drywall to studs. Sink each screw below the surface of the drywall, spacing the screws 12 to 16 inches apart.
Check that all the drywall screws are sunk beneath the surface of the drywall. With the 4-inch mud knife, load a small amount of mud into the tray and cover the screw dimples flush with the wall. When all the screws are covered, take the 6-inch mud knife and run it along the seam of the drywall, filling the crease completely.
Before the mud on the seam dries, tape the joints. Hold one end while someone else stretches the paper tape across the mudded seam. Smooth the tape into the wet mud with the 6" mud knife. Then go over the tape again with more mud with the 10" mud knife. Let dry for a day then repeat the mudding process. Allow that to dry for a day, then you should be ready for primer.