Furring down from trusses
I just received the engineering for my truss system and see that where I want to fur the 5 in 12 scissor trusses down with a 2×6 (so that I can insulate the attic out to the ext. walls), the notes say, “This truss design requires that a minimum of ½” gypsum sheetrock be applied directly to the bottom chord.”
Trusses NOT over the vaulted great room spec “rigid ceiling directly applied or 6-0-0 oc bracing.” Bracing is allowed in lieu of rigid ceiling elsewhere in the house.
I still want to add additional insulation like I had posted on GBA.com earlier, https://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/101764/insulating-512-scissor-truss-system, but now I need to meet the requirements of the truss engineering too.
Furring down from the scissor truss removes the sheetrock from being “directly applied” to the trusses AND creates a hinge between the sheetrock (diaphragm) and the truss.
Before I talk to the engineer, is there some way that a combination of blocking and/or bracing would satisfy the structural role of the sheetrock? The obvious need is to prevent the bottom chords of the vaulted area from deflecting laterally when the roof is under a load, snow, wind, or seismic.
I WILL NOT take any replies to this post as being legal or engineering advice. This is just ideas for a solution.
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