Home made sleep vapor barriers

Exterior humidity makes no difference to you inside a VBL. Without a VBL, the exterior humidity will affect the evaporative cooling rate to some extent (presuming I recall vapor pressure correctly from school 25 years ago).

I would suggest that a VBL might be even more useful in a humid environment because it's that much harder to keep your gear dry.

In my experience a VBL is quite comfortable when the sleeping bag would have been a bit chilly otherwise. I keep hearing that they're only useful below "freezing" but I haven't heard why. Wouldn't it work at 40F in a very thin bag that's normally only good to 50F?

I suspect that part of the advantage of a VBL is that it fills with methane gas which must insulate better than normal air. It's always fun to open it in the morning and experience all the night's flatulance at once!

Shaw Forry said: "Last winter I made a vapor barrier jacket from a space blanket and it turned out rather well…."

I would love to see some pictures of this. particularly the details.

I was thinking btw that packing tape might work for Mylar. It seems to bind really well on plastic and permanently and unlike duct tape heat/body warmth doesn't make it gooey thus loosing it bond.

If I can't find a heavy weight mylar bivy I'm thinking it'd be easy enough to tape up a mylar emergency blanket or two.

I'm thinking in leui of a zipper the opening can just be left reall wide.

For reasons only known to Canadians, we have large orange trash bags, a useful colour for ground-to-air signalling etc.
They may exist in Europe or the USA.

Similarly, we have Tyvek house-wrap sealing tape, specifically designed to remain sticky down to -10C,(+10F) called 'CMHC tape' by house builders, by the standard from the Canadian federal housing agency that is printed in black letters on the red tape.

So, I would propose 'CMHC' or house-wrap sealing tape as being way better than low-end duct tape or clear plastic parcel packing tape.

Slice the bottom out of an orange garden-sized garbage bag, splice two together, or even 3 if you are 2M tall, and voila! VB bag.

I have been carrying one in the bottom of my bag for a couple of years now with no sign of wear…though I prefer not to use a VB at all if I could avoid it….I have regretted not having one in August when the temperature dropped to -7C (+20F) on a clear fall night here in the Yukon…so I keep carrying it!

"In my experience a VBL is quite comfortable when the sleeping bag would have been a bit chilly otherwise. I keep hearing that they're only useful below "freezing" but I haven't heard why. Wouldn't it work at 40F in a very thin bag that's normally only good to 50F"?

This has been my experience as well. I have used several types of VBLs above freezing with good results.

couldn't you just cut leg holes out of that 58" sack and use bread bags over your feet and hands? it would cover most of your sweat glands :D

Just came across this thread and thought to reawaken it! I am researching the use of VB for my PCT thru-hike this spring, for cheap insulation. I tend to sleep very cold for some weird reason. I even use my 15deg.F sleeping bag in the house comfortably. I used a large orange trash bag as a jacket backpacking through Africa where the temps rarely reached freezing unless high in the mountains. Never knew I was using a VB until I joined this forum. I am currently sitting in my house wearing the same orange trash bag I used for my backpacking trip. Have been in it about an hour, and I am very comfortable. Observations: 1. comfortable temperature 2. not too comfortable against skin 3. lots of noise when moving
Questions: 1. how long should it take till I overheat? I heard people saying they use VB only when below freezing, but its about 68 deg. in my house, and I seem fine. 2. Would it be ok to use a light shirt (under armour?) under the VB to make it more comfortable? Anyway, I am thinking of sleeping in it tonight and will post more as I think of it. Chao!

Morning update:
Woke up late. Didnt overheat all night with a light sleeveless under armous under my garbage bag, wasnt even wet in the morning. About 68 deg F in my house, and I slept under a down comforter. How is that possible? I thought I would overheat for sure, considering people here said they wont even touch a VB until freezing or below.
Evan

are you a sweaty person by nature? I am and 10sec under one of my cuben quilts in the house and my feet and legs start to sweat, about a min and i am ready to get out. I am for sure a very sweaty guy (330lbs and i'm sure 1/2 is water) so for me i can't use VB unless i am in cold temps. I think body type can play a factor in this one.

-Tim

Evan,

Do you see your reflection in a mirror?

Just sayin'…….