How to Mud a Shower

Mix the thinset mortar in a mud tray according to the directions on the package. The thinset mixes with water and should be the consistency of a milkshake. Mix the thinset with a 5-inch putty knife.

Scoop up thinset so it covers 2 inches of the end of the putty knife blade. Apply the thinset over nail holes and seams, holding the putty knife at an angle. Fill and smooth the compound in a single pass and scrape off excess mud into the mud tray.

Continue filing nails and seams with the putty knife until the room is complete. Measure the seams between the cement board with a measuring tape, and cut strips of alkali-resistant cement joint tape to the measurement with a utility knife.

Center the tape over the seam and press down evenly with the putty knife. Repeat for all seams between the cement board.

Apply another coat of thinset mortar over the tape with an 8-inch mud knife. A mud knife is similar to a putty knife. The larger mud knife allows feathering of the edges to reduce visible seams when finishing the wall. Scrape off any excess mud.

Measure outside corners and cut metal corner strips to size with tin snips. Attach the metal corner strips to the corners with drywall screws.

Apply thinset mortar evenly over each side of inside corners with the 5-inch putty knife. Cut the joint tape to length and fold it along the center seam. Install the tape seam into the corner and smooth out each side with the putty knife.

Add a coat of thinset over the inside and outside corners just as you did the seams with the 8-inch mud knife. Allow the thinset to dry for 24 hours. Sand seams and nail holes with a sanding block and medium-grit sandpaper. Wipe down with a damp rag to remove sanding dust. Apply a second coat of thinset if necessary.