For 2x8 joists, I cut 11 1/2-inch-long, 5-inch-wide pieces of flashing tape. I peel off a 1 1/2-inch strip of release paper to attach that part of the tape to the joist while the remaining 3 1/2-inch-wide portion of the tape stays protected by release paper.
The tape should reach more than halfway up the sides of the joists, so that later it can be overlapped by the top piece of flashing tape.
I use both hands to stretch the flashing tape evenly and form an arc around the bottom of the joist without too many wrinkles.
Before installing the upper piece of flashing, I make a pair of 3-inch-long diagonal cuts in the housewrap, starting at the top corners of the joist, to create a head flap.
After removing the narrow strip of release paper from the second piece of flashing tape, I center the tape on the joist and bond it around the top half, so that the upper legs overlap the lower legs.
Finally, I fold the flap of housewrap back down over the flashing tape, and seal the cuts with scraps of flashing tape.