I would like to build an 8 feet span arch in a master bath. I'll attach 2 x4 studs on the side walls to support the top plate (2x4) on the ends. The top plate will span about 8 feet across. The problem is the joists supporting the drywall ceiling run in the same direction as the top plate.--As a result, there is no solid wood above the drywall ceiling where I can screw/nail the top plate to. I was thinking of using hollow wall toggle bolt anchors to secure the top plate to the ceiling. What's your opinion? How close should I space the toggle bolts? Will the ceiling drywall alone be strong enough to support the arch?
After the top plate is attached, I would attach 1/2 inch OSB and then 1/4 inch drywall to finish off the arch.
Any and all opinions would be welcome!
Block between the existing ceiling joists and nail the top plate to those.
Around here, the guys will drywall the the walls but the actual arch is made from 1/8" tempered hardboard. They tape and float it, texture it and paint it. Looks like it works since this has pretty much been the standard for several decades.