How to Apply Joint Compounds to Durock Cement Boards

Tape all of the Durock seams and joints on the wall with self-adhesive drywall tape. Smooth the tape over the seams and joints. Press it down firmly.

Apply joint compound over the tape with a drywall knife. Load up a small amount of joint compound onto the drywall knife. Hold the knife at a 45-degree angle to the wall. Smooth the compound over the tape in a very thin layer. Extend the compound out from the tape on either side by about 1/2 inch on each side.

Turn the knife and scrape any excess compound off with the edge or flat part of the knife. Continue until all tape is covered. Let the compound set for at least four hours. It should be hard to the touch when it is ready for the next step.

Cover over any nail or screw dimples with joint compound. Use a very small amount of compound on the knife. Scrape it over the dimple to fill in the area. Scrape off any excess compound and let it set until it is hard.

Sand the joint compound smooth with a fine-grit sanding block or sandpaper. Sand over the joint compound until the entire surface is smooth and level. This step gets rid of any ridges from uneven application of the compound, and helps give the wall a smooth and even appearance for finishing.