How to Cut Drywall for Sloped Ceilings

Measure the area to be cut. For sheets that terminate slightly past the ceiling joists they are mounting on top of, split the difference so the edge of one sheet covers half of the width of the joist with room for the adjacent sheet to also sit halfway over the joist. This allows both pieces to be screwed into place on the same joist.

Stack the drywall vertically for easy maneuvering during cutting.Transfer the measurements from the sloped ceiling to a piece of drywall with a tape measure and pencil.

Place the T-square against the face of the drywall so it aligns with the measurement. Score the piece of drywall across the face with a utility knife, guiding the blade against the T-square. Apply only enough pressure as is needed to score the drywall's surface.

Press your knee against the seam you just cut and bend the piece toward you; the drywall will naturally fold along that seam.

Reach behind the piece and cut the remaining drywall connecting the two pieces by pulling the blade of the knife along the opposite seam to separate the two pieces.

Create cutouts for lights or electrical boxes with the keyhole saw. Insert the tip of the blade into the drywall and push. It will slide in easily so you can cut out the hole. Hold the handle and apply pressure in the direction you want to cut as you saw in and out.