Its not age its condition and that applies to pilots to!
Would you wear an older parachute (+ 20 years old)? Or is this a case of no way would I buy/wear a 20 year old parachute? Assuming it has been stored properly and inspected and repacked on schedule. Just curious what others think.
It is not age its condition.
It is recommended you never leave your parachute in your plane.
You should store it as much as possible in temp, humidity controlled environment, like in your house.
You should also have a container for it. Old luggage makes a fine case to store it in; I especially like an old hard case style luggage.
Ditto on:
http://www.silverparachutes.com/ Allen's site. I have been to a few of his lectures. I have posted many links from his site. Well worth a read through. He's a real jumper that caters to emergency parachute crowd. For a round chute there is no need to ever jump, to use it in an emergency, BUT!!! you better do some reading, thinking and dry runs on the ground. Read my previous post on the subject.
My "silk" is military surplus 28 foot C-9 in paraphernalia softie shell/harness. The canopy is in perfect condition after many years. I was told there was no life limit, and military canopies have higher opening speed limits.
Why would there be any UV damage?
Are you storing it in a sealed luggage container in your house? If you leave it laying around in the sun, dirt, heat and humidity, than it might not last very long.
Of course I never have "used it" except to get packed on occasion.