How to Finish a Hardie Board Ceiling

Remove all residue from the studs in the ceiling, including old drywall. Check your ceiling to ensure that it is level, and your rafters are even; with only 3 to 4 mm difference between studs. HardieBacker board will not install properly on uneven studs.

Lay out the Hardie board in the desired pattern, either horizontal or vertical so the joints do not line up, and measure. Cut the board with a circular saw to fit your location or score them with a utility knife and push down on the score to snap the board. If you score and snap the board, you may have to cut through both sides of the fiberglass finish. Try to use one piece of board if possible. Split the rafter in half between boards if you are using more than one Hardie board.

Install a moisture barrier above the Hardie board if you are installing it in a shower or wet area. Screw the edges of the board into the center of the studs or rafters. Stagger the boards so that your joints do not line up. Leave 1/8 inch between each board.

Remove all dust and loose particles by wiping the board with a damp sponge.

Fill the joints with tile adhesive so that it is flat against the top of the board and fills all the cracks using a spatula. Tape the joints with fiberglass tape to secure all the openings.

Caulk any joints between the ceiling and walls of the board to seal them. Allow the joints and the caulking to dry before setting your tiles.

Apply a thin layer of tile adhesive over all of the tape and joints.