How badly does UV affect tents?

Simon,

I don't think you'll know the answer to that until something goes wrong! Obviously, the advice is to limit UV exposure as much as possible, but as the deed is done, I wouldn't worry about it too much. To my knowledge, there's no after-sun cream for tents, so you'll just have to go on using it and perhaps it will fail on you sooner than if you didn't leave it out.

If you have to pitch it again for long durations, I would consider rigging a cheap, thick tarpaulin (canvas is good for UV protection I believe) over the top of your tent. It will also help keep it cool inside during the day, warm at night and keep resins from trees from harming your tent. You'll also get a nice dryish patch around the tent and bring in less mud.

John

UV degradation will certainly have an impact on all the qualities of your textile products.

(That goes for rope as well)

One season in the Antarctic with a new weather-haven tent, after 3 months it was faded beyond recognition. But that is at an extreme end of things.

Polyester is less sensitive to UV degradation than nylon. Silicon coating or Pu coating. It doesn't matter the nylon just cannot cope that well with loads of UV.

365 days in normal weather (alternating clouds, rain and sun) nylon will be degraded to almost crumbling fabric.

So if you invest heavily in an UL nylon tent you sure better not use it for car camping or basecamp use. As long as you pitch it every afternoon/evening again then you'll have many many years of fun from your nylon tent. If you regularly pitch it for overstaying on same spot it might degrade on you quicker than you'll like.

For over staying, basecamp usage your better of with a polyester or even a polycotton mix (poly cotton dries quickly but breathes great and is waterresistant, very nice fabric for luxury tents).

As to repairs? Only replacement of affected panels is helpfull. Reproofing coating is just temporarily measure, it's postponing the envitable. In the end the fabric will rip easier, much easier in the affected spots.