SynMat UL 7 Limbo: How Low Can You Go?

I used one recently down to 0c and it was fine but any colder I would of wanted some foam underneath it.

High Sierra Sniv- 29oz, 16.5oz of down
Synmat UL- 15.2oz
Montbell UL pants- 7.8 oz, 2oz of down
Down Jacket (Assuming same model as pants)- 8.0 oz, 2oz of down
=
60oz sleep set up, with 20.5 oz of down

1- lightest way to add warmth is to add down
2- Nearly all down clothing (excluding perhaps Blackrock items) are less than 50% down
3- sleeping pads are often the weak points of cold weather set ups

If you were carrying the down jacket and pants anyway (as I'm assuming you might in cold weather), than speaking strictly of weight this is an efficient option.

A 1/4 inch pad from prolite gear (for example), in a large size, is cheap at 20$ and adds 7 oz at the most. you could even ditch the down pants (assuming they are only for sleeping) and come out on top.

The lightest option for a sleep set up would be to have a CCF pad and a quilt with more down, but this excludes worn items.

In conclusion, shelling out a couple of bucks and a few ounces for a CCF pad seems like the logical choice. I have a blue foam pad from BIG5 that was 6 or 7 dollars, weighs 6 ounces, and is my 4 season add on for sleeping in the snow

I was out the other night, 26 degrees at bed time w/temps holding steady if not rising. I sleep COLD and was in my Kelty Light Year 0 bag w/light wool top/bottom. My Exped UL7 did fine but any lower and I would have wanted a warmer pad. FWIW.

The Exped UL7 is warm to about freezing at best.

This past weekend I spent one night in a snow cave with a UL7 and I've been out in similar or colder temps a few other times this winter. I had a thin (1/8") Suluk 46 PG Sheet (maybe R 0.5) under the UL7 and then snow under that. The snow cave warmed to 0C/32F, and the snow under my pad would have been 0C as well, since it was a little bit melted in the morning. I had a warm quilt and lots of down layers on, so most of me was warm except I was losing a lot of heat through the pad. It doesn't really matter how much down you have on if your pad isn't up to the challenge because down won't really stop you from losing heat through the pad.

I couldn't sleep on my back without getting slowly chilled because of the heat being lost through the pad. Sleeping on my side reduced my contact area with the pad, so I stayed warm enough to sleep when I was on my side.

Even on dirt in 30-35F conditions you'll feel the heat being lost through the UL7. I'd take the warmer down mat and preserve a good nights sleep.

– 7C on snowgrass with a 1/8" Gg foam layer on top.
Was fine.

Caution: snowgrass can be a good insulator itself.

Cheers

With pad itself, I have been good down to freezing. By adding a 1/4" ccf pad I have been down to the lower 20's but it was a bit cool under me. I was sleeping in silkweight long underwear, socks, a down hood, and a down vest draped over me. This is with a quilt that has 9.4 oz of down.

I've used my UL7 down to around 5*F. The ground was frozen and there was no grass anywhere. I was using a MHW Phantom 15 bag with old REI midweight bottoms, lightweight fleece top, and Marmot Zeus jacket (MW wool socks and fleece cap, of course). I was in a SMD Skyscape. The temp dropped a bit lower than I was expecting, but I was not unbearably cold. I've definitely been colder with my old Thermarest pad, and at higher ambient temps. I'd probably add one of the Gossamer Gear foam pads to supplement in the future, but I'm extremely happy with my UL7.

When I most recently used my Synmat UL7, I was a bit cold for the first hour or so, but became comfortable and slept well at outside temperatures in the high 20s F. But I was in a dome tent, not under a tarp. I had an MYOG cuben down quilt with 3" of loft, and I had a distinct sensation that the heat I lost was principally down through the pad. I would have been cold and unhappy under a tarp, on that pad, at those temperatures, I think. I plan to look for a warmer pad for winter use.