How to Drywall an Interior Attic Valley Rafter

Place the first sheet across the rafters at the attic's highest point; have your helper hold the board in place so that the long side runs perpendicular to the rafters. Drive nails or screws through the drywall at the rafters; space the nails or screws 7 inches apart down each rafter. Hang subsequent sheets with the short side butting against the short side of the previous sheet.

Measure the last section and cut a drywall piece to fit if it is shorter than a full drywall board. Cut drywall by hooking the end of the tape measure over the end of the drywall and holding it with one hand, pulling the tape the desired length with your other hand, locking the tape in place with your thumb and sliding the tape with both hands down the board while holding a utility knife blade against the drywall. Mark the distance, draw a cut line and cut the board with the utility knife if you are uncomfortable holding the tape measure and knife at the same time.

Begin the next row with a half sheet so the vertical seams are staggered by row. Continue hanging until all the rafters are covered.

Scoop a dollop of joint compound with your drywall knife and press a thin coat along the length of a seam. Follow with a strip of drywall tape along the seam. Press the tape into the mud with your drywall knife and cover it with a thin coat of joint compound. Scrape away any excess compound and let dry overnight.

Apply a second thin coat and let it dry. Apply a final coat after the second and let it dry. Sand to smooth with medium-grit sandpaper. Coat with paint primer and paint, if desired.