we've opened up family room to include kitchen. small overhead storage room involved. installed 2x4's both sides of wall for support. removed wall. 17' span. glued 2 2x10's together using wood clamps (with screws) installing 2x4's at each end. also installing support in the crawl space directly under the 2x4's. Q: once the header is up what is the easiest way to make sure the 2x4's are snug under the beam. is using shims permitted or just an exact cut to height?