Install a nailer
I hate redoing any miter, but I will if that’s what it takes. Also, I always install a nailer for the crown molding even if the trusses are running perpendicular. A nailer takes the guesswork out of finding the trusses/floor joists and guarantees the crown will stay in place.
Submitted by New Hope Remodeling @newhoperemodeling
Consider using a jack miter
A jack mitre is basically a combination of a butt joint and a mitre joint. So why use a jack mitre? Basically, the jack miter gives you extra strength and minimizes the movement of the wood, which means that there’s less of chance of gaps. Plus, the jack miter creates a much smaller glue line so there’s no glaring glue mark after your casing is painted. And, jack miters are just cool!
Submitted by Seth Vyn @sethvyn