I used to be a military survival instructor. We used parachutes to build tee pees. My advice, buy one or forget about the idea. Its a lot of hassle for which a lot can go wrong or be done wrong.
One thing, you need (if i remember right) 24 gores of a round chute, of which I'd venture to say that 99% of rounds are porous. Meaning microscopic holes, requiring the material to be stretched drum tight to have any water resistant characteristics. Approximately one tug away from O $h!t, i ripped it!

With these rounds, you need to remove all the inner parallel lines from the chute. Not doing so will not allow the material to stretch.
You'll need anywhere from 15-25 pop can sized round poles about 30 feet long. The variance depends on the season (snow= more poles).
You'll need what Native Americans used to call "whale bones". These are used to keep the parachute from slipping, loosing its tightness.
Due to the chute being porous, the structure will need to be erected at approximately 60 degrees to have any ability to shed water.
Some things to be aware of. Square chutes will not work. Although they are non porous (typically) they are square. Tee pee's are round

If your lucky enough to find a round nonporous chute, its likely to cost a bunch as the shelf life on such a creature is rather long.
These shelters are cool, but cramped, hard to maintain (they need tightend up about every three days) and generally a pain. Also, note that heat rises. Tee pees are tall. Good summer shelter. Poor for the winter.
My two cents again. Cool for the kids, rather neat to see, needlessly cramped, a pain to erect/ maintain. Buy a tent, or a good sill tarp.
Bill