Like many I use a Tyvek ground cover as part of a bivy / tarp system. I have been so pleased with the performance of the Tyvek below me I thought why not try it above also. Using my bivy as a pattern I cut a bottom sheet and also a top cover out of the Tyvek. Using a nosew high tech bonding (superglue)method I attached the two and closed off the foot end. First time out I crawled in (not under my tarp) under a clear night sky only to wake up to the sound of light rain hitting the Tyvek top cover. With daylight near I decided to wait it out, my close inspection upon crawling out reveiled a dry sleeping bag with no condensation and or rain penetration. This may have been just plain dump luck, time will tell. I plan to make a new Tyvek bivy this weekend taking alot more time and care, I will post pictures of my effort if there is any interest. I have not weighed the bivy but will when I complete the new one. It was a fun project and only cost me the time and effort (I already had the tyvek and glue). If nothing else it keeps my dogs hair off my gear. It's OK to laugh at my first effort at making my own gear.
