How Do I Install Cove Molding?

With large cove moldings, a professional carpenter told me to use a sliding 10 or 12 inch chop saw to do the deep compound cuts. Smaller chop saws just don't have the depth.

Another trick I learned is not to cut exactly 45 degrees.  Cut 44 degrees or 46 degrees either on the inside or outside joints so they slightly interfere at the visible part of the joint.  Then apply some pressure as you mate them and you'll get  a real tight fit.  If your corners aren't perfectly square, you'll have to adjust for that too.

A pneumatic nail gun is a real backsaver.  Rent one if you need to.  Trying to position your pieces and nail them up while holding yourself up in a corner is a real feat.

Make sure you have extra pieces.  It will take some practice to get good results.  Good luck.