>>473940The waterproof coatings that a lot of manufacturers use can degrade after prolonged exposure to sunlight. I believe silicone is the material that is the most susceptible to degrading after prolonged exposure. A lot of modern manufacturers use a type of urethane coating on the outside of the rainfly and silicone on the inside of it. In all my life camping, though, I've never had a rainfly lose its waterproofness from just ordinary use. I'm also not familiar with synthetic materials turning "brittle" after less than a year of use.
The key to understand is that you're not supposed to leave backpacking tents set up continuously, and definitely not for months at a time. They are meant to be set up in the evening, broken down in the morning, dried off, and kept in your backpack through the day. Yes, synthetic materials are less durable than canvas. That's the trade-off for having a shelter that is light enough to be comfortably carried all day in your backpack.
If you are seriously considering leaving your tent set up for "8-20 weeks" at a time, then I suspect that you live in a hobo camp, or some other sort of degenerate commune, and intend for a tent to be your primary place of residence. In which case, /out/ is the wrong board for you to ask this question. I'd suggest /b/ or /soc/ instead. Please only post threads here when you actually intend to discuss outdoor recreation.
