Insulating under my cot for winter.

[Moondog55]

OK a thread resurrection from a different forum.
Preparing for my winter fixed ski camp I'm glad I didn't toss the old doona I used in my failed warm poncho effort. I'm going to fold it in half lengthways and use it under my old army cot. So I can use just enough air in my mattress for comfort.
My question; is it better to use a full box shaped cot cover to keep the airflow to minimum or will a simple length of wind resistant fabric suspended under the cot and fibrefill be enough?
I've used undercot insulation before but always minimum thickness plus a radiant barrier, this fibre doubled will be full 155mm thick and almost touching the tents floor, old Australian arm y cots are low to the ground.
I'll also be using an old yoga mat on top but that is more for back support than insulation, still that mat is also 20mm thick and quite warm too.
Is 200mm from the ground enough tho? I can afford a cheap LW cot, I'm still not that overweight and I do lose a lot of belly fat when I ski.

[Heavy Duty]

I think that would work. Stopping convection by having insulation between two layers of wind resistant fabric should do the trick. Now, it may have to be thicker depending on how far you want to push the lows at night. Experiment and report back if you can. I'm curious.

[Moondog55]

Will have to buy a new stretcher. Using this double layered but folded to give space between layers the last layer is sitting on the ground. Even folded tight it sits on the ground. Fixed camp a wider and taller cot is probably better anyway being more comfortable. Got a cheap polyester microfibre sheet at the Op-Shop for $5- Light and windproof and the right size when folded up. Will take pictures when finally assembled, finding a bigger but light weight cot will be the main problem

[Bkrgi]

I'm going to say don't worry about a wind resistant anything if your always in a tent. I would keep things as breathable as possible. If the insulation is going to be solely for this purpose use some shock cord to hold things up. Take your cue off of how Hammock underquilts are done and wrap the shock cord tight to each side of the cot. You do not want any void airspace or the cold will creep....things must be snug without squishing. It might be equal to making a net using the shock cord.

[Moondog55]

I take your point.