Groundsheet for bivvying - yay or nay?

[ScotRoutes]

I've not been using one. My original bivvy bag was fairly substantial and my mat was under it. However I'm now using a Ti Goat Kestrel with the mat inside and I'm thinking it might be handy to have another layer to protect the bivvy bag (and mat).

What do other folk reckon and what do you use?

[benp1]

Groundsheet only if I don't have a bivy

Bivy is always straight on the ground

[middleagedmadness]

Tyvek under both my helium Bivi or borah gear one ,like to keep the undersides free from dirt and any chance of mold

[TheBrownDog]

Yep, on the rare occasion I use my Hunka, I have a groundsheet to keep the mud, leaf mulch and grime of the forest floor off my kit. Ive been using an old tent footprint, but just got a sheet of Tyvek, which is larger, lighter and packs down smaller. Under a tarp, I'll just use a groundsheet, especially if its not too cold.

[PeterC]

I've got a Ti Goat Kestrel too and use a bit of old flysheet cut to size. As BrownDog says mainly to keep the mud etc off. Not sure if it would help much with the really prickly stuff. I need to buy a wee stove from Stu so thinking of a bit of Tyvek at the same time. It's secondary use is as something to sit on especially if the ground is a bit damp.

[Charliecres]

Silver survival blanket is the minimalist solution. Works well and can be re-used many times before disintegrating. I have also trimmed one and folded a foot pocket/flap to keep the bag from touching the inside of my tarp.

[RIP]

Yep, not a bivvy bag user but always bung a sliver of tyvek under my mat for dirt protection. V useful additional benefit is as a changing mat - top half of mine is wider so I can keep things clean(er) when (un)dressing lying down when it's pissing with rain, windy, and muddy with the tarp in 'low tunnel' mode.

[whitestone]

Never bothered but I suppose it depends on how wet/muddy your chosen bivy spot is. I sometimes take a small square of Tyvek to use as a mat to stand on whilst changing.

[Bearbonesnorm]

I don't like washing kit if I can help it, so mostly use a Tyvek / Permavent one beneath my bivvy bag. Probably not so important with a heavy weight bivvy bag but something like a Ti Goat or Borah is very thin and doesn't have the most waterproof of base materials. I also sew elastic straps to the groundsheet to hold my sleeping mat in place.

[Al]

Polycryo (the clear stuff you stick over drafty windows) is super tuff and very light.

[wriggles]

Tyvek under bivvy/mat for me too. As well as keeping kit cleaner it also prevents punctures to my Exped sleepmat

[Ray Young]

Unless it's heavy duty then just how much extra puncture protection are you going to get from something like tyvec? Surely if something is going to go through your sleep mat then it's just as easily going to go through tyvec as well.

[RIP]

"Polycryo" - hi Al, am just trialling this meself. Certainly super-light, but main problem I found is I can't see the blasted thing in the dark! Maybe a line of luminous paint round the perimeter...

[lune ranger]

Another vote for tyvek.
It's slippery as hell and crinkles like a crisp packet in a cinema when new though.
A good tip I was given on here is to wash it a couple of times in a machine to get rid of the worst of it.
I think a ground sheet a bit bigger than your bag adds a bit of comfort and makes camp admin - food prep, getting changed etc a little bit more pleasant and easy

[Bearbonesnorm]

Tyvek does have a certain waxed paper quality when new, whereas Permavent is much softer and feels more like material. I keep thinking that I should make up some groundsheets ... Inbuilt pillow pocket, peg points and mat retention straps.

[RIP]

A groundsheet with the BBB "Roaring Bear" printed on it would be ace .

PS> Congrats on your 15000th post Stu! Doesn't seem ten minutes since your 10000th .

[ScotRoutes]

Tyvek does have a certain waxed paper quality when new, whereas Permavent is much softer and feels more like material. I keep thinking that I should make up some groundsheets ... Inbuilt pillow pocket, peg points and mat retention straps.

Aye, but what colour?

[Bearbonesnorm]

Aye, but what colour?

I'd probably use Permavent Colin, thankfully it only comes in the one

[middleagedmadness]

If you wanna cut one stu,450 mm wider than a synmat7 and 300mm longer, without pillow pocket but with peg points pm me how much and I'll PayPal gift you the money

[benp1]

Polychro is an option, and one I've used before, but I found it a faff

I usually bring a sit mat with me on bivi trips, means I can sit down without getting a cold or wet bum. Which also means I can get changed and stand up on something, take shoes on/off etc

I'm mat inside bag and bag straight on floor. I do appear to be an outlier though...!

[ScotRoutes]

I'm mat inside bag and bag straight on floor. I do appear to be an outlier though...!

That's what I've been doing but I can see advantages in having another layer.

[benp1]

The problem I had when I used a ground sheet was that when I folded it up both sides ended up getting wet, which sort limited the value in having it in the first place. Although I suppose it would stop water coming through by water pressure alone

I used to use a CCF mat under my bivi but the neoairs are relatively robust so hasn't been a problem so far

I actually have a bearpaw (I think) bathtub mat, haven't used it in ages. Used it inside my supermid when I wasn't using a bivy

[slarge]

Polycro sheet here. Completely waterproof and cheap and light, so if it rips it is no bother. All my kit goes on it, and if I ever slept out without a tarp it could be folded over me for a waterproof layer. I’ve use a silver blanket for the same purpose and that works well but is a bit more fragile.

[Jamesh]

Silver survival blanket is the minimalist solution. Works well and can be re-used many times before disintegrating. I have also trimmed one and folded a foot pocket/flap to keep the bag from touching the inside of my tarp.

I use this approach too. Those blankets really pack down to nothing

[In Reverse]

I've got a Rab "Ground Cloth" which I'll occasionally take if I think the grass will be wet or there's rain forecast. Light enough, sturdy and seems to do the job. https://rab.equipment/uk/nylon-ground-cloth

It's nice having a dry bit of ground under the tarp just to put stuff on or sit on sometimes.