The most common method of installing crown molding is shown in the photo below of our bathroom ceiling. As you can see on the photo below, this is a standard crown mold design applied directly to the wall and ceiling of the bathroom. It’s also not a large size crown molding.
The drawing below is a larger crown molding of the same basic design and applied in the same manner. In the drawing there is a 1 X 2 nailer applied to the wall and against the ceiling. This nailer is not necessary for the smaller crown molding used in the bathroom because nails easily reach the 2 X 4 plate behind the sheetrock and this serves as a nailer. I advise using the nailer for larger crown moldings.
Some don’t consider it critical for the larger crown moldings and avoid it by using longer nails. I prefer applying the nailer to ensure that the nails holding the crown molding penetrate sufficiently. This is a simpler installation because the wall and ceiling controls the location of the molding. There is one critical thing to notice with this type of crown molding and not noticing can cause serious installation mistakes. For clarity I found a drawing on the web that shows this well and it appears below.
The most important thing described in the drawing above is the angle. Many believe that this type of crown molding is based on a 45 degree angle to fit the 90 degree angle of the wall. The actual angle from the wall is 38 degrees. If you measured it from the ceiling it would be 52 degrees which totals 90 degrees. Keep this in mind to ensure that your moldings and cuts fit correctly. To go to lesson two click HERE.
There will be two other pages of information related to crown moldings and the various ways to install them. This will include information on how to cut large crown moldings using standard size compound miter saws.