Greetings. I lurked frequently on this forum while building my own home and got some helpful tips. I wanted to contribute an idea to give back.
I recently built a deck on our house over a walkout basement, so the deck is 10 ft in the air. I wanted to block the rain somehow to create a dry outdoor workspace, but didn't like to Trex Rainscapes price tag. (roughly $1200 for the area)
So I covered the top of the joists with Grace, bought 14" aluminum flashing (joists 12"OC), and made a trough between the joists pitched at 1/4 inch per foot. Basically there is a real slight dip in the flashing at the start of the run, and then it runs down to a roughly 4" dip at the far end of the joist bay. I stapled the flashing on both sides of the joist every few inches with stainless steel staples. All materials were around $200.
Cutting the Grace into strips, cutting the flashing, and custom bending every piece was time consuming. This makes my solution probably unrealistic for a customer, but good for a cheap homeowner.
I hope this helps someone who wants to avoid the Trex price tag.