Tyvek insulation properties

[petemaz]

Strange one maybe, but does anyone know if a tyvek groundsheet offers any insulation when sleeping on cold ground?

[RIP]

All the best questions are strange . Unless you have some interesting bedding arrangements, presumably you'll have no insulating air trapped between the ground and the sheet or the sheet and your body so no help there. Can't see it doing much against conduction - it's usually 0.15mm thick so its R-value must be about 0.0000001. Unless you use Tyvek Thermawrap or Reflex.... My empirical view is that I have a tiny bit of tyvek to sit on to get dressed, and I can say that in winter my arse freezes within about a microsecond of sitting on it! Am interested in the full technical details from our chums here in the trade....

[jay91]

My guess it not much or nothing at all

[ScotRoutes]

http://www.dupont.com/products-and-serv ... #Question5

Do Tyvek® weather barriers have an R-value?
No; however, properly installed Tyvek® weather barriers help protect against loss of R-value in insulation due to wind washing. Even at wind speeds of 5 mph, a wall without an air barrier retains less than 40% of its original installed R-values.

[Lazarus]

congrats you just proved that if you have some insulation there already it can improve it
Unfortunately your question was about whether it insulates on its own not whether it can improve other insulators

I also go with none at all - have you see how thick it is not? What material, at that thickness and on the ground, would have an r value worth getting excited about ?

I have an off cut you can have but i am certain the padded envelope it would come in will be of more use

[petemaz]

Thanks for the replies... confirms what I thought. So is there a cheap, lightweight, packs-small product of some sort that I can stick under my mat during the winter months to offer insulation from the cold? Current mat has an R rating of 4.4.

Thanks

[RIP]

Apologies if I'm misunderstanding, but isn't the mat doing that job admirably already with its R4.4? If you're tarp-only, reckon there's nowt wrong with a bit of tyvek/polycryo bunged down first to keep things clean and tidy though - but probably that's just me being needlessly house(tarp)-proud . I'll be taking a dustpan and brush with me next at this rate.

[petemaz]

Well I bought the mat in the US last year and only used it a couple of times in early summer in the desert so I wasn't sure if it was up to a cold, Scottish winter! I've previously used a down exped mat that was great over winter, so I guess I was thinking I'd need some additional insulation...just in case!

[RIP]

"cold, Scottish winter". Insulation:

SxRlicR by Reg, on Flickr

[Lazarus]

American r values are 5 x the UK value so that r could well just be a summer mat with no insulation in it*

https://www.ultralightoutdoorgear.co.uk ... ained-i206

Better mat being the solution there- i dont think anything else light weight will give a comparable r value to a winter sleeping mat and I don tthink there is another solution

I have seen folk use silver backed tyvek type liners and also what looked like silver and bubble wrapped - found it on a construction site so cannot advise on what it is or if it works but there are other materials - I suspect they will all be bulky though not that heavy.


*that said my winter insulated one only has a r value of 4,2 US and is fine - though I am not in Scotland temps

[Bearlegged]

I've got a friend who does ultra running races, stuff like the spine challenge etc.
He tried making a DIY superlight mat out of bubble wrap, and tested it when we went bivvying in June.
He was bloomin' cold all night, and jacked it in to head home at about 4am.

So yeah, get a proper mat.

[BigdummySteve]

"cold, Scottish winter". Insulation:

SxRlicR by Reg, on Flickr

Bowmore 15 works well, glendfibidlih will just keep you away while you ponder missed opportunities.

[middleagedmadness]

I know you said a Scottish winter but as you already have a Irish in there WHERES the teelings small batch ?

[Bearbonesnorm]

Tyvek will do nowt from an insulation point of view. Best light (but not overly small option) would be some thin foam used to insulate beneath laminate flooring.

[petemaz]

Ah, if only I liked whisky....lol. Thanks for the bit about difference between US and UK 'R' ratings, I didn't know that and seems very misleading. My current mat is a Klymit static V lite, which claims to be 4 season.... So suitable for winter camping in the UK?

[Bearbonesnorm]

A US R rating of over 4 should generally be fine for year round UK use.

[petemaz]

A US R rating of over 4 should generally be fine for year round UK use.

[mechanicaldope]

Ah, if only I liked whisky....lol. Thanks for the bit about difference between US and UK 'R' ratings, I didn't know that and seems very misleading. My current mat is a Klymit static V lite, which claims to be 4 season.... So suitable for winter camping in the UK?

I have the Klymit Ultralight V (insulated version r4.4 US, there is also a non insured one) which was fine on last years, admittedly boiling, winter event. There was ice on the ground in the morning so must have got pretty cold.

[ScotRoutes]

I use a Synmat UL7 all year. I was out last night on frozen ground. R value (I assume US) is 3.1.

I've thought about using that thin foam used under laminate flooring as I have a chunk of it left over from insulating the van. I reckon I could get a 3/4 length part stashed in my harness quite easily. I've not "needed" it yet though

[Al]

I’ve used similar stuff to this in cheap campervan conversations and ended up with off cuts - works really well as a sit mat or a boost for a thin sleeping mat for winter use. Weighs very little too.

https://www.screwfix.com/p/ybs-thermawr ... lsrc=aw.ds

[ScotRoutes]

I’ve used similar stuff to this in cheap campervan conversations and ended up with off cuts - works really well as a sit mat or a boost for a thin sleeping mat for winter use. Weighs very little too.

https://www.screwfix.com/p/ybs-thermawr ... lsrc=aw.ds

Yeah - I make pot cosies/meal cosies out of that stuff and some duct tape. Great for keeping food warm when you're eating it or waiting for it to re-hydrate.

[Charliecres]

I’ve used one of those car windscreen frost guards as an extra insulator under a mat. It works but is surprisingly bulky.

[petemaz]

Thanks for all the responses folks, much appreciated. I did think about the thermawrap stuff, so if I feel I need some extra insulation I might try and source some (cheaper than buying a new mat!).