I've been replacing the windows in my house with new-construction style vinyl windows, and along the way, I have run into some problems with flashing. The current siding is crappy masonite T111 over 15# felt, and no sheathing. At each window I have torn everything off down to the studs, nailed 7/16" OSB sheathing on, and covered over that with 30# felt. I have done a lot of research on felt vs. other house wraps like Tyvek, and decided to go with felt because of it's time-proven results, and I don't like the idea of sealing an old house up too tight and potentially introducing moisture problems down the road.
Anyway, the problem is, at each window I wrap the felt into the rough opening, caulk the flange and install the window, and then add peel-n-stick flashing tape over the flange, shingled from the bottom up. I've found that even in our warm Texas weather, the flashing tape doesn't stick to the 30# felt worth a damn (I'm using Protecto Wrap BT25XL, because that's what my local big box home improvement stores carry). Obviously, when I install the window trim, the nails go through the flashing and it's not going anywhere, but I'm worried that the flashing is not providing a good seal.
Any suggestions for getting the tape to stick better? I've seen some recommendations for using spray glue as a primer. I like the idea of having a strong seal around the windows rather than just lapping the felt over the flanges, but I want to feel confident that it's going to hold up over time. Should I go a different route, like flashing the window directly to the sheathing before adding the 30# felt? How then (other than gravity) would you keep water from moving horizontally back under the felt from the window edges?