I am building a 20 foot wide barn with a gambrel roof. The trusses are specially engineered so that no chords are needed (almost like a scissor truss). This allows me to use the top of the barn as a loft. But, I want to raise the height of the walls on which the trusses are supported by 18 to 24 inches so that I have extra head room on the loft level of the barn. Normally, the floor joists would stop the wall spreading caused by the thrust of the roof, but since I am raising the wall height, that is not the case anymore. Will I have a problem if I don't add any more supports elsewhere (I am not about to use flying buttresses on my barn). One potential solution I have is to use some cross bracing from the top of the wall down inward to the floor joists at an angle every so often along the wall, like:
/ / / |\\ | \\ |----\\--------- |
That way I get the extra head room, and the braces won't be in the way. Any thoughts?