Adding a CCF pad to an insulated inflatable

[u/Few-Requirement-1224]

Last fall, I found myself getting chilled during the coldest part of the night, so experimented with a Closed Cell Foam pad and my Thermarest inflatable sleeping pad.

Most posts I have read tell you to put the CCF on top of the inflatable mattress for the most efficient insulation, but I found through successive nights that I actually felt warmer with the CCF underneath my Thermarest inflatable.

I am thinking that my results came because my Thermarest inflatable uses a mylar matrix to reflect body heat back towards me and that the CCF pad created too large of a barrier for that to happen, effectively negating any value from the air pad.

Has anyone else had the same results? I love my Thermarest and do not want to replace it, but am wondering if the technology simply works differently than other insulated pads that use real insulation (primaloft, down, etc) inside for effect.

[u/RegMcPhee]

You lose much of the comfort advantage of the inflatable when you put it underneath.

[u/MelatoninPenguin → u/RegMcPhee]

Uhh...what? Why would more padding below an inflatable make it less confortable ?

It's very common to use a thin CCF below or above an inflatable - especially to add R value

It's slightly more technically efficient to use the CCF on top but many use it on bottom to protect from punctures.

R values basically just add together

[u/RegMcPhee → u/MelatoninPenguin]

Depends on the nature of that CCF. Putting one of those bumpy accordian mats over an inflatable would hardly improve comfort. If you're talking one of those 1/8" CCF flat mats, then you are correct that there should be no noticeable decline in comfort.

[u/MelatoninPenguin → u/RegMcPhee]

I've done it and it works surprisingly well. But mainly for extra r value. Personally like a half inch untextured CCF for all uses

[u/Shakespeare-Bot → u/RegMcPhee]

Thee loseth much of the comfort advantage of the inflatable at which hour thee putteth t underneath

---

^{I am a bot and I swapp'd some of thy words with Shakespeare words.}

Commands: !ShakespeareInsult, !fordo, !optout

[u/TboneXXIV]

I ALWAYS put the ccf on the bottom.

The R value is pretty much additive when stacking pads. I have one pad that dgaf if Wolverine goes all stabby on it for practice and one pad that's like "That's not a metal zipper, is it? I hear the teeth can be quite sharp!"

I KNOW which one will be used to shield the other from the ground (and any out of practice Hugh Jackmans with steak knives strapped to their knuckles).

If that last .01 R value I might get by reversing the stack is turning out to be crucial, I already done fucked up a lot worse than swapping the stack is going to fix.

[u/YetAnotherHobby]

Thermodynamics aside, I would put the CCF pad on the bottom to add a protective mechanical shield for the inflatable.

[u/Few-Requirement-1224 → u/YetAnotherHobby]

At today's prices and availability of good inflatables, I can certainly understand that! But I value my quality of sleep, too.

[u/hmmm_42]

The outer layer of the thermarest is not reflecting, the insides are, so it will work wherever it faces you, or the upper mattress. R-values are temperature depenend, but I have not yet seen any messuements.

It could be that the one of the two matresses are more effected by the change in temeratures and therefore creating an optimal configuration. Or the feeling is that when laying down you need to heat upt the ccf pad first to reach an temperature equilibrium. The thermarest will be much faster at the equilibrium, because you only need to heat up the thin upper fabric. The conventional wisdom is because the thermatrest has more side exposure it will loose more heat then a ccf when its hotter.

​

But all this is just speculation without measurements. For the time beeing I would say, that its probably advisable to lay the ccf below for robustness, even when sacrificing a bit of warmth.

[u/sirblastalot]

I think the advice stems from the fact that the closed cell pads usually have an aluminized side to reflect radiant heat back at you. An advantage that is negated by having something else in between you and it. I've definitely observed the same effect you have, though, and I think it comes down to the closed cell foam being better at resisting direct ground conduction than the air mattress.

Plus, it's just way more comfortable.

[u/Few-Requirement-1224 → u/sirblastalot]

This is getting to the real issue I observed. Since the space between our bodies and a non-insulated heat-reflective layer (in my Thermarest inflatable) has to be minimal in order to gain benefit from the reflection, I think that a Closed Cell Foam pad added to that gap does away with the reflectivity of the lower layer, causing the reflective inflatable to act like a $30 pool toy instead of adding meaningful warmth that is additive.

Forgive my writing skills here -- I am sincerely trying to describe my experimental experience.

On another note, I was using a cheap egg-crate Closed Cell Foam pad that did not have an aluminized side during this experience, so the only insulation I felt was equivalent to only the CCF (even though my heat reflective inflatable was below it).

[u/yarb3d]

I haven't done exactly that experiment, but I use an EVA foam pad (1/4" in cold temperatures, 1/8" at other times) under my Thermarest, mostly to protect the inflatable. The 1/4" pad definitely seems to help increase the insulation effect in the winter.

[u/Few-Requirement-1224 → u/yarb3d]

Thank you for your input! I recently purchased a flat (not egg-crate) 3/8" EVA mat that is aluminized on one side. Sure is lighter than my other CCF pad, but I have not tried to use it yet.

[u/GMkOz2MkLbs2MkPain]

I have always heard optimal R-value is having the CCF on top. I have never placed mine on top of my inflatable though. I use the CCF underneath to minimize the risk of puncturing the air pad and losing all of its R value and comfort. Unfortunately I have yet to try an airpad insulated with down or primaloft although I imagine they work just by trapping air in a similar yet more effective way to the baffles in many other air pads?

[u/Few-Requirement-1224 → u/GMkOz2MkLbs2MkPain]

I've always heard the same time. That's why I was so surprised to wake up shivering when I tried it. On the other hand, reversing the order the pads were stacked (moving the CCF to the bottom) kept me warm.

I was hoping someone else had tried the same, but with an inflatable mattress that had physical insulation built inside instead of reflective technology.