Before applying adhesive to the pieces, it is best to cut and fit the entire room. Start by deciding where to place designer miter blocks. Add divider blocks to your layout so that the distance between any two blocks is less than a full length of molding.

For the best results, blocks and molding lengths should be fixed in place with an adhesive caulk as well as nails or screws into studs and joists. We recommend using a premium paintable, siliconized or super latex, latex adhesive caulk. It will fill any seams left between the molding and the wall or ceiling due to their unevenness and cleans up with water. One 10-1/2 fl oz (300 ml) tube of latex caulk is enough to install about 25 feet (7.6 m) of crown molding.

Complete the installation of all designer miter blocks first. This will allow you to cut molding lengths slightly long and spring each length into place snugly against the blocks. Caulk should be applied in a continuous 1/4" (6 mm) bead around the edges on the top and back surfaces of each block. Fasten the blocks in place with two or more trim head drywall screws.

With molding lengths, apply caulk, again in a continuous 1/4" (6 mm) bead, along both the wall and ceiling bedding surfaces of the crown molding. If the piece abuts blocks or other lengths of molding that are already fixed in place, apply an epoxy or polyurethane (PL) adhesive to the ends of the molding.

Spring the molding into place. Use trim head drywall screws to fasten it in place. Any remaining voids can be caulked. Excess caulk can be removed using a wet cloth.

To complete your installation, fill the screw or nail holes using a clean, wet putty knife and a sandable non-shrinking latex filler (spackling). Filled holes should be primed before painting for the best results.

Cutting Crown Molding Miters
Corner joints must be cut using compound miters if you are not using internal and external miter blocks. The best way to cut these compound miters is described here.