Stormproof bivvybag pattern?

http://www.therainshed.com/

Bivy sack. Item #147

Do you have any specs your looking for?

ken i made my bivy that way but honestly i'm always worried water might drip down the side edge into the bag… the inner side material tends to drape, which is great for air flow, but maybe bad for rain.

I Have the Outdoor Research Aurora bivy it uses a calm shell top that's easy to get in out of. When it raining just shove your sleeping bag deep in the toe end of the bivy to get out and in. Bivy are pretty easy to make they are basically giant waterproof envelopes for people.
The only reason I don't make my own Bivy is I don't have the means to get a hold of gortex fabric to transfer sweat out and keep rain out thats designed for tent use verse jacket gortex fabric. I don't own the equipment to seam tape the bivy I made to make it completely waterproof. For $150.00 to $200.00 you can get a better made product from Outdoor Reasearch or Bibler/blackdiamond you know will keep you dry and out of the elements.
IMHO

Terry

You definitely need a waterproof/breathable top. I found a material that is 2.3 oz/sq yd that is fully waterproof and very breathable. I seam seal it using dental syringe and SeamGrip. I also make mine big enough to get dressed in. The downside with most bivy sacks is getting in or out in foul weather. Having it big enough to get dressed in makes it easier to face to outside. Still only 1.5 lb. with poles.