Tent footprint – help me choose one

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Someone posted that the polymicro is the same plastic as that used for winterizing patio door windows that you can buy at a hardware store too. That way you can cut it to exact size.

Do Tyvek and Polycro come in different weights? I just checked out the Polycro groundsheets from GG: 1.5 oz, not bad. How does Tyvek compare in weight?

I'll have to look into the hardware store replacement for polycro–do you think the material is strong enough to take grommets so I can insert my tent poles?

Clearly you don't NEED a foot print. If you don't want to get your gear dirty – don't bring it out into the woods. But you knew that already.

I have the footprint for my Hubba and its pretty darn light. You'll can make your own footprint, but if you make it from Tyvek it'll be about the same weight as what you have.

The thin plastic ones are your lightest alternative.

Be carefull to make the footprint SMALLER than your tent floor on all sides. Otherwise it will funnel the water to the area under your tent and if your tent floor never leaked before it certainly will with an oversized footprint.

A small footprint though leaves a border of the tent floor that is not protected by the footprint and that border will get wet and muddy. You just can't win.

My vote is for no footprint. Just pack the tent carefully with the tent floor folded up against itself and it won't get the rest of the tent or your gear dirty. When you get home, clean it, dry it really well and put it away.

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David, the Tyvek groundsheets are about double or slightly more than double in weight to polymicro and Tyvek is not 100% waterproof. The utility in my mind of polymicro or spinnaker (which is a weight about halfway between polymicro and Tyvek and which folds up much nicer–I have a spinnaker ground cloth for my squall classic by GG–GG sells spinnaker ground cloths) is that it will (a) keep the tent from being very muddy in a bad rain, (b) provide some protection against puncture and (c) provide extra waterproofness for bathtub floors that are thin to begin with–ie, the squall classic has a very thin bathtub floor, it feels like the floor is equal to the ceiling of a tarptent.com rainshadow 2 tent (I own both tents). The floor for the tarptent.com is so strong, we do not worry about a groundcloth for it, but for the squall classic, I favor the spinnaker ground cloth as a compromise between weight and convenience — polymicro just is not as convenient to work with than spinnaker for groundcloth — polymicro is kinda sticky to itself.

Kristin,

Are you saying that the sole benefit of a groundsheet is to keep your tent bottom clean? If so, I agree that a groundsheet is superfluous. My wife, however, is concerned about prolonging the life of the tent floor. Do you think this concern is warranted, or will my tent floor withstand abrasion well? (I might add that I am a casual backpacker with only 2-3 trips per year at present).

As far as making my own groundsheet, how would you tension it to your tent poles? Do you think that grommets will hold in polycro or not? My Hubba Hubba groundsheet is around 50" x 98"–slightly larger than the one sold by GG. Thus, it seems I would need to use cord to attach it somehow to my tent poles and keep it immobile.

PS–How much does the MSR groundsheet for your Hubba weigh? Dimensions?

David:

If you think about it, any nylon or plastic good enough to offer your tent meaningful abrasion and puncture protection is going to be pretty hefty in weight.

For me, with or without groundsheet, it just pays to spend 2 extra minutes to inspect the ground — the area is small — so kicking off sharp objects really is pretty easy. So, if you are going to do the inspection anyway, you don't need to haul hefty protection. In any case, most all nylon/plastic provide very poor protection against puncture from sharp objects anyway.

I didn't read all the replies so apologies if this is a repeat. I've been using 2-mil plastic sheeting (aka painters cloth) that's available in any and all hardware stores, Wal Mart, etc. One roll costs $2-3 and provides enough for 2-3 groundsheets. I'm on my third one in 5 years of use, averaging 10 bag nights per year. Weight for one cut to the size of my Seedhouse 2 SL is just under 4 oz.

The plastic sheeting will help keep your tent floor clean and dry — and provide some abrasion resistance. My Seedhouse is 4 years old now and the floor is still in perfect condition.

What with condensation and all, the sheeting is sometimes wet with mud in the morning. It's a lot easier shaking/drying the sheeting and then folding the dirty side to itself — then trying to pack a tent with a wet, muddy floor that you know will make the entire tent — inner and outer — all wet and muddy.

Tyvek will work too, but I dislike them. Tyvek is a bit heavier, but a lot more bulky compared to 2-mil plastic sheeting. Tyvek also has a habit of attracting dirt to its surface (static?).

David:
I made a custom footprint for a hooped bivy (Black Diamond Light Sabre), using what would equate to medium duty paiters plastic. My grommets started tearing out in 2 nights. It didn't work for me.

David,
If you provide the requested size and pay for shipping I will send you a tyvek footprint free, what a deal. Having made this offer I will say that you may be able to find a scrap of tyvek large enough from a local building contractor.
Thom

Ben,

Thanks for the suggestion–how do you recommend I keep the sheeting in place under the tent? Do you tie cord around the corners and tension to your tent poles, or have you installed grommets like the OEM groundsheet?

Do you think the 2-mil plastic is more abrasion resistant (significantly so) than polycro?

David:

I would say both types of groundsheets will give some protection, but If there are jagged stones, they could damage both. In the desert, one sharp cactus needle will can also pierce them (as well as heavy, dedicated nylon footprints too).

I've tried 1-mil, 2-mil and 4-mil — and for me, the 2-mil seems to be the best compromise between weight and protection. Again, I'm pretty careful with site inspection — and even with the lightweight 2-mil plastic, one sheet will last me a very long time. And my tent floor is still in perfect condition. Best $2 investment IMO.

Edit: Forgot to answer your other question…

For groundsheet, just cut a piece more or less the same shape as your tent floor, but 2-3 inches smaller all around. Once you plunk your tent down, the groundsheet won't go anywhere. You don't need to mess with grommets at all.

David,
The footprint for my Hubba is heavier than I thought, weighs in at about 5 ounces on my postal scale. It has tie out and grommets, probably much like the one you have for your Hubba Hubba. I still think Tyvek footprint would be of similar weight, particularly if you added tie outs and grommets to it.

Speaking of tie outs and grommets, I don't think people who use home made footprints generally add them. They just do what Ben does, buy some painters dropcloth at the hardware store and cut it to size.

So does it stay in place? Well kind of.
Does it protect against dirt and mud? Well yes in the middle, but not along the edges.
Does it protect your tent floor against punctures? Maybe somewhat, but if you really want abrasion protection you're back to Tyvek or your store bought footprint.

So what's the point? It does keep your tent floor in better condition, and if you think you may want to sell it that is important.

Ben,

I just came from Wal-Mart. The 8' x 12' dropcloth weighs 1 lb (according to the packaging)! If this is true, then a groundsheet for my tent will end up weighing 8 ounces, the same as the factory one.

How come yours weighs less?

Unless I can drop in weight, it looks like I'll have to go with polycro…or just stick with my factory groundsheet.
:(

Again, you can get the polymicro from Home Depot – look for the plastic that is used for patio door window temporar winter insulating (you know, you use a hair dryer/blower to shrink it tight). comes in a couple of brands. cut to size.

Dave — how did you figure half?

Total pack – 12' x 8' = 96 sq. ft. = 16 oz. weight.

Hubba Hubba – 84" x 50". Cutting a piece 3 inches smaller all around means 78" x 44" or 6.5' x 3.7' or 24 sq. ft.

24/96 = 1/4 and 1/4th of 16 oz. is 4 oz. Ergo, your drop cloth groundsheet weighs just half of a store-bought one.

David,
I have goone through all the footprint options except polycro. The 2 mil plastic should weigh 1.3 oz/sy, 1.1 silnylon weighs 1.4 oz/sy (after coating) and Tyvek Housewrap weighs 2.0 oz/sy (measured after shrinkage in a washing machine).

The 2 mil plastic punctures easily. The 1.1 silnylon is significantly more puncture resistant. Finally, the Tyvek is significantly the most puncture resisant.

The 2 mil plastic is super cheap. Both the silnylon & Tyvek are about 5 times more expensive (still, only $10 for a tent).

IMO, they are all waterproof enough under a tent floor.

Just a note about cutting Tyvek: cut it the SAME size as your tent because it will shrink in the washing machine. You will want to throw it in the machine with plain cold water to soften it up and make it quiet.

Also, I don't need grommets or tie-outs on my footprints. If it's windy, I place a couple of smooth rocks, sticks or spare gear on it until I get the tent on top of it, then remove the objects.

I find it striking on this forum, where so many are focused on low weight, that so many are suggesting you need a groundsheet or a footprint. It strikes me as unnecessary weight, and I think a ground sheet can make moisture under the tent worst, if condensation or water gets between the groundsheet and the tent and gets trapped. I find very little water gets under the tent when raining, and to the extent any does, it soaks freely into the ground. A groundsheet definitely increases the time it takes to dry the bottom of the tent by trapping any water between two impermeable layers.

I retired my previous tent this year, it was 20 years old and had been used extensively. I never used a footprint. I mostly hiked in the northeast, but did take it on trips out west, including river trips in the desert. On occasion, I do remember noticing something sharp like a needle poking through the bottom: but this sort of micro hole never amounts to much. With a freestanding tent, you can fairly easily inspect the ground under the tent. A tent bottom gets very little or no abrasion. My guess is that what will eventually do in a tent bottom (and probably long after the fly is fried by UV) is delamination of the waterproofing.

There probably are places and situations when using a groundsheet is a good idea. I have just been too lazy and cheap and light to ever carry one.

Ben,

I'll have to go remeasure my Hubba Hubba groundsheet. I think the GROUNDSHEET was around 4' x 7'. Area = 28 sq. ft. The sheet at Wal-Mart is 12' x 8' = 96 sq. ft. 96/28 = 3.43. Thus the groundsheet made from 2 mil plastic would be 4.66 ounces. You're right…about half of my OEM groundsheet…not sure where my mind was when I wrote that.

4.66 ounces still seems a bit much to lug around, though, to bolster my tent floor. Since the tent floor is already pretty durable (cordura nylon?), I was hoping for a lighter, more disposable alternative.

Michael,

I never considered silnylon. I know SOME tent floors are made from this stuff, so it ought to be semi-durable. Where can I obtain silnylon in the size I need?

Methinks silnylon is even heavier! The aforementioned polycro is lighter, but more expensive.

I wouldn't bother with it but if you MUST have a footprint under your tent, use non-waterproof fabric that does not absorb much water (light wt polyester is better for that but nylon will work). That way when water does flow under the tent (it will, you can't always find a suitable tent site) it'll do what comes naturally …. soak into the soil.

If you are concerned that you'll end up tenting in puddles or ad hoc streams (it happens occasionally), use a poly sheet INSIDE the tent. Cut it the shape of your tent floor but 12-18 inches longer and wider so it can turn up the sides of the tent to make a bathtub. In a multi layer floor you want the highest water resistance closest to you and your gear. 3 mil poly resists a larger hydrostatic head than good PU coated or Si impregnated nylon floors … I'm not sure about 2 mil … I just don't know either way.

The aforementioned polycro is lighter, but more expensive.

If you buy your polycryo as window insulation at a hardware store, it will cost less than silnylon (maybe not if you can find silnylon at WallyWorld but I can't shop there and stay married;-)

David,

Silnylon comes in about 60" wide pieces. Buy it by the linear yard (36"x60") at http://www.thru-hiker.com or http://www.seattlefabrics.com or http://www.owfinc.com

Get the "seconds." They will work just fine for about 1/2 price. Don't worry, they don't look like a slice of swiss cheese :-)

If the footprints shows any abrasion in the future, it's easy to recoat it with silcone made by GE available at Home Depot mixed 1:3 with ordorless mineral spirits.