Optimum Tent Floor Material with or without groundsheet.

Both ideas have merit. But both have deficiencies as well.

UL tent floors have not one but two deficiencies. The obvious one is fragility – well, lower strength. But many of us have hammered silnylon floors for many years, so that one is debatable. How careful are you?

The less obvious problem is that UL materials often have a lower hydrostatic head rating. For a fly a HH of 15 psi might work – maybe, but when you kneel on that fabric on wet ground the water will come through. You need a significantly higher HH for a floor. This means more weight – if you can find the fabric.

Using a groundsheet under a tent floor will help to protect the fabric – up to a point. If you are putting your tent on cactus spines, a groundsheet is not going to offer very much protection, regardless. Very sharp shale may also cut through. Sharp pointy sticks can still make holes right through.

But the more insidious problem is that you may still get wet inside the tent. It can be very hard preventing water from flowing over the groundsheet sometimes, so kneeling on a UL floor can still mean water comes through. It depends a bit on where you are camping.

For the tents I make I prefer to use a slightly heavier fabrc for the floor, with a higher HH rating. Finding such a fabric can be hard. Most silnylon these days does not have a good HH rating.

Cheers

Roger covered the topic quite well.

Just one additional idea. For a couple decades I used a water barrier that runs up as high as the floor's bathtub walls inside the tent. It needs to have a higher HH than the tent floor. The inside floor surface gets wet but we and our gear stays dry. 3 or 4 mil poly worked great … 6 mil for boy scouts:-). Any water that made it's way under the tent is free to soak into the soil as much as it will handle.

When I was concerned about damage to the floor I'd sometimes bring a non-waterproof sheet for under the floor. But that's too much weight for me these days.

I haven't used that approach since I started tarping or tarptenting but this thread has got me thinking that I might try a window insulation sheet (aka polycryo) with corner guys running to the mitten hooks of our Rainshadow 2 next time I head out expecting wet soil conditions.

As Jim mentioned, there's always the option of going with the light+waterproof+cheap option of polycro, *if* you could figure out a good way to make it replaceable. Tape works great for repairs during trips but you'd want a way to replace the floor completely too.

You could tape the ends together to make it a bath tub floor pretty easily, you would just need a way to attach it to the tent. I can think of a few:

-Omni tape (snag-free velcro) would work, but then to replace it you have to sew more velcro onto your new polycro sheet, not ideal
-Plastic snaps would be easier to replace on polycro, but the polycro is probably more likely to rip there, and they wouldn't provide a complete seal like polycro
-Tape? Sew a small perimeter of something that tape would adhere to on the bottom of your inner, then just tape the polycro on. You could either use tape that you can peel off, or stronger stuff that you'd just cut the polycro when you want to replace it. The second option would result it getting slowly heavier over the years as small strips of tape and polycro get added on the bottom. Probably to the tune of an ounce every 5 years or so. ;)

"Shield" silnylon from thru-hiker.com has higher HH. 1.5 oz/yd2.

If you put a hole in it, just glue on a piece of silnylon with silicone caulk diluted with mineral spirits or Permatex or whatever.

You might have to put some silicone inside so it isn't so slippery.

For my next DIY project, I'm thinking of making a replaceable tyvek bathtub floor. I realize this might not work in really wet conditions, but the rains we encounter are generally not the sort that would cause a river to flow under the tent and soak through the tyvek. We could always add a layer of polycryo inside on trips with heavier rain potential, to protect the bottoms of the pads from getting wet.. You might consider tyvek as a floor; it wouldn't be that much trouble to rip out and replace if it wears out.

Has anyone tried tyvek floors, and if so what was your experience?

Derrick,

My current strategy on myog tents is as follows:

(1) Tent floor is made of light uncoated nylon.

(2) I place a plastic sheet inside the tent. The tent walls keep the plastic sheet edges turned up in a bathtub floor fashion to keep water from running over it.

When the tent floor gets dirty I can run the whole tent (not fly) through the washer because it made entirely of uncoated nylon.

I can replace the plastic sheet when it shows signs of wear.

@ D K

For the bottom of my bivy sack.
I soaked the tyvek (type 1443R) with diluted silicone.
It fills the spaces.
Heavier but more durable and waterproof.
The surface is less slippery.

"It is much easier to replace a groundsheet then to sew in a new tent floor. Ergo: Use a .75 silnyloncuben floor with a 1.75 tyvek groundsheet, and keep the tent floor forever and simply replace the groundsheet"

I prefer this method with a polycryo groundsheet for the reasons mentioned plus a "less-than-technical" reason: sustained inclement weather + less than ideal camping surfaces = a lot of dirt, mud and detritus on the bottom of my shelter. A dirty/muddy ground sheet can be shaken off and stored separately on the outside of my pack.

I have tried a single floor system and went back to using a GS primarily for this one stupid reason.

Thanks everyone.

After lots of thought and considering every type of material out there I am definitely leaning toward the double floor system: Ultralight tent floor and cheap replaceable, but still light groundsheet.

The question now is which materials to use for both:

1. Tent Floor – 1.1 oz coated silnylon or .74 or 1.1 oz cuben. I expect to go with cuben here for both weight and waterproofness, but do prefer the softer texture of silnylon. I think .51oz cuben would be too fragile.

2. Groundsheet – Will finally try 0.6 oz polycryo, although I am not optimistic it will hold up to backcountry use. Or, other options are 1.8 oz tyvek varient (HomeGuard Housewrap, with which I have lots of use experience – it works but is a bit heavy) or a reasonably light 1.3 to 2.2 oz PU coated silnylon.

Opinions?

Thanks again

Derrick

Derrick,

Here’s another option for the ground cloth portion.

It stays in place nicely due to the adhesive.

here

I definitely second the idea of a separate ground sheet. It's also dual use because you can sit on it when it's rained recently. I haven't used the ground sheets from gossamer gear but I did use window film from a hardware store on my AT thru-hike and it lasted the whole trip without a single hole. It only weighs 3 oz for a two person tent and I'm still using it. You might want to check out the sil argon from dutchware. It's what I'll be using in my new net tent. It seems waterproof and durable enough and is a lot cheaper than cuben.

Again, thanks everyone.

I picked up some polycryo (window sealant) for the groundsheet – weighs in at .64 ozsqyrd. And I am going to go with the Argon and see how that works for a tent floor. Total floor weight will be 1.75 ozsqyrd.

Derrick

Hi Derrick,

Any update or feedback on your materials choice?

I'm planning on making a bivy and net tent in the coming weeks and am leaning towards the system you chose: lightweight floor (either Argon or Cuben) on top of a polycryo groundsheet.

Also, do the two layers slide around a lot and, if so, have you tried adding silicone or another material to keep them in place?

Thanks!

I just got a new Tarptent Moment DW. After seam sealing it inside and out I coated the outside of the tent floor with a small roller using a 5:1 mix (by volume) of odorless mineral spirits and clear GE silicone caulk. I pit it in a pint sized can and shook it very well to thoroughly mix it.

After coating the floor I then gently wiped it down with heavy duty blue paper "shop towels" to remove the excess. I let it dry in full (Las Vegas) sun for two days.
I think this will reduce wear on the floor fabric as well as make the hydrostatic head impervious to pressure from, say kneeling inside the tent on saturated ground. We'll see. I'll report back at summer's end.

If I expect very abrasive conditions like southern Utah I'll take my light plastic painter's cloth ground sheet. cut 2" smaller than the footprint.