Tyvek Bivy

Hmmm, should generate some ideas. Can't beat the price, unless you make your own.

I ran into a couple on the AT that used homemade Tyvek bag bivies under a Ray-Way tarp. Said they had been doing this for years and were perfectly happy with them.

You could slit these down the middle to maybe half way if you only need to protect the bottom, sides and/or foot of you bag.

I'd bet they would custom make on request?

Wow….that is a great price, it would cost just as much to make one yourself. Has anyone tried it yet for a bivy?

I though of making one the first time I laid out Tyvek to cut for a ground cloth. I was thinking of just taping the side.

The person with the Tyvek quilt bags makes them by hand. Perhaps she could make one to your specs.

My conclusion was that an Adventure Medical bivy would be a better bet unless you had the spare Tyvek and the skills to make a decent one.

Sorry, sort of related question. Any ideas as to how a tyvek bivy would perform relative to the more expensive materials, ie Momentum or Pertex, for breathability?

I don't think Tyvek is near as breathable as the materials you listed.
In fact if I was going to use tyvek, I wouldn't use it as a full bivy, maybe half bivy with a full floor. That way breathability wouldn't be a problem.

I tend to not use the upper half of my bivy much while tarp camping.