Hi all,
Husband and I are using a JRB Mt. Rogers quilt but are having trouble pushing it to lower temps because of draftiness. I'd like to make a bottom that attaches with velcro (quilt has full-length velcro closures on both sides), but I don't know whether the fabric should be breathable (i.e. uncoated nylon, lightweight woven polyester, silk, etc.) or whether I would get better results with silnylon. Would the lack of breathability wind up soaking the down? Of course, we are sleeping on CC foam pads anyway... TIA for your suggestions.

I've done it both ways: breathable and coated. If you sleep in a shelter with a floor, then breathable will be lighter and a little more, well, breathable, with little risk of outside ground moisture being a problem. That said, most foam pads themselves aren't very breathable. So a breathable undersheet really only adds ventillation at the parts that extend beyond your pads.

Silnylon won't soak up any moisture, but is prone to static pickup of dust, a consideration if that might bother you. For the location full waterproofness probably isn't necessary unless you use the quilt in the same conditions you'd use a bivy sack.

Normally a quilt and under sheet extends beyond pads. If you both side sleep the undersheet can lift up and be an uninsulated "side" that gets chilly. So you might want to consider a light 1.1 ounce uncoated nylon with polyester insulation on the floor only where it isn't covered by the pad. Thru-hiker.com has fabric and insulation.

Building an insulated tongue or double horseshoe collar also helps double bags or quilts to be less drafty. My wife and I usually carry down vests or jackets that get pressed into service as draft collars, but I keep thinking a built-in would work better.

You'll have a hard time finding a polyester as light as 1.1 oz nylon and silk may not be durable enough for a floor.

If you go with a 1.1 oz uncoated nylon, consider a dark color for fast sun drying if it gets damp or wet.

One benefit to a coated silnylon bottom is it can be used on top as splash guard for short periods if rain or spray is a short term problem. Even a dwr treated breathable nylon helps some in that case. A bottom sheet will get dirty killing any dwr fairly quickly. So before trip laundering in Atsko sportwash and retreat with a dwr if that doesn't revivie repellancy is advised.

Maybe the JRB folks would have some advise. I bet they've prototyped just such a bottom sheet and might have experience with what worked or issues to lok for.

Heather,

My date and I sleep under a standard sized Nunatak dual arc alpinist, and after comparing its width dimension to your JRB, I might suggest adding a down filled “wing” to each side of the torso section of your quilt. At shoulder, the arc is appx. 19 inches wider than the JRB, and if side sleeping, or changing sleeping position, I can imagine the 61” width as drafty.

Our quilt also has an insulated tongue that Neil wrote of, and having used a double quilt without, I would never have guessed the comfort that it adds to double quilt sleeping. It is an excellent suggestion.

The foot box girth of the Nunatak is narrower than our previous quilt, and although I think it restrictive, especially at the shin area, it is much warmer. If the JRB folds in half in the foot area, its foot box dimension would be comparable to our old quilt. (A converted bag).

Our Nunatak also has three girth adjusting ties, and although we never shorten them, each of us uses our respective ends to draw the quilt closer and warmer. Lying on the ties, with the excess between us, seems to keep the adjustments intact.

Finally, when temperatures drop into the thirties and below, my date adds her Reed rain pants and a wind shirt to minimize skin-chilling drafts while sleeping. She is much more tolerant of any casual bellows draft since.

After enjoying the flexible pleasures of bottomless dual quilt sleeping, we would take a few steps before adding a bottom sheet. In any event, good luck!