Looking at the load tables for various products, purlin hangers are often shorter than the actual size lumber they're supposed to hang:
The size difference seems more consistent at lower dimensions. For instance, 2x4 purlins are 3 7/16" high and 2x6 purlins are 5 3/8" high.
Why is this? Won't the joists end up higher than the header? Is something supposed to go on top of the header to offset this so the subfloor is level?
I'm using purlin hangers to hang floor joists inside my walls, which seems to be a suggested usage of these products.
Perhaps others can put this problem better than me. Check out the reviews and question on the USP JPF at Lowes.
Just to be sure we're all on the same page, this is a purlin hanger being used to hang floor joists. Only difference is I'm using solid sawn joists rather than i-joists.
Perhaps the foam tape supposed to make up the difference?