I found this link about preserving the quality of the tissue paper pattern itself, but it doesn't answer your question about protecting the patterns from disintegration due to humidity, etc. (Preserve Paper Sewing Patterns)

Reading a bit more here and there, I noted on chowhound that most foodsaver bags are not biodegradable until thousands of years have passed, and yet other info mentioned food saver bags break down over time and becomes air permeable. Maybe mylar bags would work better? Perhaps it's all about not only what you use, but the seal too.

If I was doing this, I'd probably use lightweight interfacing on the pattern itself and hope it doesn't decompose (I have no knowledge or even guesses about this!), and/or I'd just opt to double bag the patterns in food saver bags and then put them in a tote that has a good seal on it. HTH!

Food saver would be your best bet to keep the moisture out because it seals air tight. I think moisture and mildew would be the biggest threat to paper patterns but nothing is fool proof. I think I'd find a place to store them upstairs. I'm not knitting as much as I used to and I wanted my storage place for other things. I gave some yarn away but some yarn and patterns I wanted to keep. I bought a couple of those storage cubes that you can use as a stool and put them in 2 of my bedrooms. I selected colors that would go with my decor. One holds my patterns and 1 my yarn. They don't take up much room and can be used for extra seating or a small table by a chair by putting a tray on top

I gave away perhaps hundreds to a friend. I suspect he sold the vintage ones on Ebay. I didn't have the patience. I kept very few, because even if the styles cycle back to something similar, there are differences in fit and details that would make the old patterns look dated. I have perhaps two dozen patterns I kept. If they didn't fit in the file cabinet in the sewing room, or in the dresser I keep there for thread and sewing supplies, I'd keep them under my bed.

The solution may be to order a subscription to Burda Pattern Magazine. Patterns come in the magazine, they don't take up space unless you trace them off, and Europe is way ahead of my geographic area style-wise. It will be a couple years before they look out of style.

Food saver bags in a plastic tote sounds fine.