How to Cut a Bullnose Drywall Corner at a 45-Degree Angle

Hook a tape measure's metal edge onto the corner wall stud, and measure from the wall stud to the last piece of installed drywall. Transfer this measurement onto a full-size piece of drywall. Place two marks on the drywall's surface -- one near the top and one near the bottom.

Intersect the two marks with a 4-foot level. Cut the drywall following the level's edge with a utility knife. Bend the drywall along the cut line. Cut through the drywall's paper backing.

Take a second measurement from the same wall stud down the corner's other side. Transfer this measurement to a second piece of full-size drywall and cut it the same way you cut the first piece.

Ask a friend to hold one of the cut pieces of drywall in place while you hold the other one. Line up each piece's edge with the corner wall stud's edge. There should be a small gap between the two pieces at the corner.

Drive drywall screws through the drywall pieces and into each wall stud they lay over. Use four drywall screws per stud, and sink the screw heads slightly below the drywall's surface.

Take two new measurements above the first two pieces of drywall you just installed on the 45-degree corner. Cut two new pieces of drywall to fit those measurements.

Test fit the two new pieces. Line up their edges with the corner wall stud's edge, and rest their lower edges on the first two pieces' upper edges. Secure these two drywall pieces in place the same way you secured the first two pieces.

Continue to install drywall up the corner until you reach the ceiling. Measure the corner's height from the ceiling to the floor. If you will be installing baseboard around the corner, subtract the baseboard adapter's height from this measurement.

Transfer the measurement from step 8 onto a piece of bullnose corner bead. Cut the corner bead to length with tin snips. Set the corner bead over the 45-degree corner. Drive drywall screws through the corner bead's holes and into the drywall to secure it in place.