Originally Posted by warbonnetguy
our silnylon is waterproof to 2000mm which is more than enough to avoid actual misting.
like others have said about condensation... hanging close to the top of the tarp, possibly having the doors closed when they should be somewhat open (depends on how windy it is) along with high humidity and cold temps all probably played a part in having condensation. in general you want the doors open some to allow venting unless it's very windy.
I agree with Brandon, I really don't think it was moisture coming through the tarp. I've had it out in plenty of the UK's finest rain this summer ( we've had a lot
) for a few hours at a time, without anything coming through. I'm convinced it was condensation. If it was misting, the inside of the tarp would be equally wet all over but this wasn't the case. I agree that it was probably the doors being closed, the lack of any wind, the saturated ground and the temps that all played a part in more condensation being formed than normal.
What leaves me a little confused though is why this happens more with sil than other tarp fabrics. I'm convincing myself that the taughtness of the pitch and the bounce of sil increases the likelihood of condensation being bounced of the inside under heavy rain conditions. Cuben and PU fabrics may have very different properties. Perhaps I should get a Cuben tarp too.... For scientific purposes only.