Lay out plastic sheeting to catch falling debris and protect floors.
Test the soundness of the drywall with a screwdriver to determine where the water-damaged areas stop and where solid drywall begins. Use a pencil to mark any areas where the ceiling is soft enough to allow the screwdriver to penetrate.
Remove loose areas of orange peel texturing with a scraper.
Cut out all damaged areas of the ceiling using a jigsaw. Make a square or rectangular cut to make replacement easier.
Measure the cut area and mark this onto your replacement piece of drywall. Cut the drywall to size.
Cut two 1-inch-by-4-inch wood strips slightly longer than the width of the hole cut into the drywall. Place them into the hole and attach them to the drywall surrounding the hole with 1-5/8-inch drywall screws.
Fit the cut drywall patch into the hole. Attach it to the 1-inch-by-4-inch backing strips with screws.
Cover the seams of the patched area with drywall.
Apply joint compound over the tape with a joint knife held at a 30-degree angle, swept back and forth over the tape. Skim off excess compound.
Sand the compound with 100-grit sandpaper to a smooth surface. Remove sanding grit from the area.
Apply primer to the patched area.
Blend orange peel texturing with an aerosol texture compound, feathering the edges to blend into the existing texture. Allow the texture to dry as directed on the packaging.
Apply primer to the texture and a coat of paint to match the rest of the ceiling.