Backing needed or not??

[Tim Hickey]

Hi Guys:
I am building a home, myself, and I am wondering if I need to install any additional blocking in the trusses where the horizonal meets the 45 degree slope that forms the beginning of the tray ceiling in the master bedroom.
The basic shape of the tray is formed by the lower cord of the trusses, in one direction, with field built formers arching up in the other. I plan on using 5/8" drywall on the ceiling. Is this stiff enought to support itself without additional nailers between the trusses and formers at the 45 degree angle? The frameing members are 24 inches on center. If I need them, I will nail them up. If they are not required, I will save the time, the money, and the energy.

Thanks for responding.

Oh, as long as I am at it, I read in the forum where one guy recommended using a flashing material at a valley for additional support to prevent cracking. Would that work in this situation?

Tim Hickey

[Steve]

There's a new product out, I got a sample of it, it's a valley metal that bends in the middle for any off angle. Yes, you do need something to back it up, otherwise cracks in the future. An alternative is to get 20 gauge track and notch them over the joists - one on each side. Also use the ULtra-Flex wide angle tape, that also holds it well, use Durabond to instead of joint compound for much extra holding power.

I threw out the name of these new valley metals, will try to source it.

[Tim Hickey]

Thanks Steve:
I will get on making and installing the blocking. I would guess we should use it both top and bottom of the tray. Although one could argue that the rock on the 45 degree plane holds up the ceiling rock. Any opinion on that?

Tim

[Steve]

The new steel backer is made by Strait-Flex and it's called something like "Renegade-X" as I recall. They sent me 8 pcs. as a free sample without even asking for it. As a drywaller myself, I was always thinking that something has to be done about this problem, that's why I use notched 20 gauge studs or track on both sides, Ya might look up Strait-Flex, it should be www.strait-flex.com, call them up and they will probably send you free samples.

The problem is that neither side of the rock has any backing and the ceiling joists will shrink and move causing the rock to move and thus crack, so the bottom holding up the upper rock is still a no go.