Installing Crown Molding: The Ultimate Guide

• Miter box
   
• Hand saw or power miter saw
   
• Caulking gun
   
• Premium paintable, silicon or super latex adhesive caulk
   
• Caulk line box and pencil
   
• Tape measure
  

• 1.5" - 2.0" putty knife
   
• Hammer and nail set
   
• Elastomeric  adhesive caulk (White Lightning™ Recommended)
   
• Extra fine sandpaper
   
• 6d or 8d finishing nails (bright finished or electro  galvanized) fasteners must penetrate substrate a minimum of one-half; to three-forths inch
  

 
• Before you begin installing your crown molding, it’s good to  plan your layout in order to determine the amount of crown molding you’ll need.
   
• Measure the entire room (the width of every wall) to find the  total length.
   
• Add 10% to this total for miter waste
   
• Divide the total linear feet buy the crown molding lengths.  These lengths usually come in eight, 12, and 16 foot measures.  So if your total wall length is 34 feet and  you’re using eight foot molding lengths, this means you’ll need five lengths of  eight foot molding at a 40 feet total. You’ll always want to round-up. It’s  better to have more molding than not enough.
   
• If you’re not using cornices, consider buying additional  molding in order to match the pattern of the molding when you’re eight foot  length ends in the middle of a wall. If your molding has a repeat pattern of  6" or greater, you’ll want to purchase an extra 5% of molding.
   
• Always store your molding in a dry area and never outside.
  

• It is recommended that you paint after installation since the  caulk that you’ll by using to help secure the molding to the wall will push  through the joints and may create some white areas within the crown molding gaps. You’ll also be using the caulk to cover the nail/screw holes created when  mounting the molding to the substrate. You’ll be using a putty knife to fill  these holes and later, extra fine sandpaper to smooth-out the caulk for  painting or staining.
   
• Clean all surfaces of molding with a cloth or wet sponge. Make  sure surface area is completely dry before installing.
  

• The first piece of crown molding to be cut should be a piece  that will be behind a door or at an inconspicuous corner. This is because  when  matching molding patterns, where  the total installed length of molding begins and ends, the pattern will usually  not match-up.
   
• Measure the length of the wall the crown molding is to be  installed on. When cutting your crown molding length, add 1/32"; to either  side to compensate for taking.
   
• Place the molding in the miter box and make sure to be aware  of the wall facing side of the molding and the ceiling facing side. The wall  facing side is usually the longer side of the molding. It would be good  practice to always place the ceiling side of the molding on the bottom of the  miter box and the wall side of the molding on the miter box wall opposite you.
   
• Measure the joint angles of your walls (inside and outside  angles) with a good protractor. For cutting joints, measure the angle where two  walls meet and divide this angel in half. This divided amount will be the angle  you’ll want to cut the molding joint at.
   
• When cutting, take note of the molding pattern. Cut the left  side piece of molding first and then match the pattern before cutting the right  side piece. Do this for all joints, inside and out.
   
• After cutting, place your cuts together to check how they fit.  If it looks good, move on to the next molding length to be measured and cut.
   
• As you’re cutting and mitering all your molding lengths, lay  them down in front of the walls that they’re to be installed on. Do this until  you’ve finished cutting all molding lengths and double check them for correct  measurement.
  

• Sometimes when crown molding does not span the entire length  of a wall, you’ll need to butt joint two crown molding lengths together.
   
• Make sure there is pattern continuity between the two lengths  of crown molding to be joined.
   
• Place the crown molding in the miter box and cut a straight  edge.
  

• The first piece of crown molding you’ll want to install is the  piece you cut first.
   
• Take the molding and add a continuous bead of ¼"  construction adhesive caulk along the ceiling and wall facing sides of the  crown molding, as well as the butt joint ends. Gently press the crown molding  against the wall and use the caulk to fill in any gaps.
   
• Next, nail or fasten the molding into place using trimhead  drywall screws or finishing nails. Make sure to place the nails into areas of  the molding where there is no ornamentation so that the nail or screw hole can  be filled with elastomeric caulk and later sanded down to a smooth finish.
   
• After the molding is secured there may be some adhesive caulk  that has been pushed out around the edges and joints of the molding. Wipe off  the excess caulk using a wet cloth. Caulk will usually dry in two to three  hours.
   
• Once the molding has been installed fill all gaps with caulk.  Smooth with a putty knife, wipe off excess and allow to dry.
   
• Sand down caulked areas to a smooth finish to prepare for  painting or staining.
   
• Paint or touch-up molding with paint or stain as needed.