I am just wondering how many people will use a footprint or some type of ground cover under their tent? My camping partners have always used one under their tent, but they are beginning to look for extra ways to cut weight and am thinking about doing away with the footprint. Their concerns are not only about the tent floor, but also about their geertop mattress getting punctured. I currently use a footprint under my Tarp tent and feel that it does offer me some additional protection. The right material will not add much weight. However, that being said I didn't use one on my last hike in February simply because I forgot to make one. My tarp tent seemed to be no worse for wear.
And I use the ultra-light footprints for backpacking, but when car-camping we have an extra step, and use heavy tarps under our tents, to minimize wear and maximize its lives. The tarps , footprint also allow us to have a "doormat" in the vestibule, which helps keep things clean. Given how worn our footprint was after half a dozen seasons, I'm thinking it's not such a bad idea to use footprint backpacking, even if it is a few ounces heavier. All these wear would be on the tent, otherwise.
It's lightweight and durable, super sure, and I appreciated having it on a super rainy trip when I made a make-shift tarp out of it so that we could at least cook and eat outside our tent. But if you're like me and don't always set up a shelter and often cowboy camp with a pad and groundsheet, it's like wrangling with saran wrap.
I've settled on geertop 20D footprint. There are different types of geertop footprints, btw. I use the 20D silnylon type, that's more waterproof and lightweight. I find that it rolls up plenty small and it doesn't feel like I'm sleeping on a slip-and-slide. I've read some negative reviews of this one that it retains moisture when it gets wet, but I haven't had that situation. Most of their reviews are positive.
Some guys said that he never really understood manufacturers making footprints and if their tents can't stand up to the abuse of a natural ground space, why don't they just make it more durable floor. Sure, it might add weight to the overall weight of the tent, but so does a footprint. They would want to consider that's a marketing ploy of the tent manufacturer? I think it gives the user the flexibility to use it or go without depending on conditions. It also allows the tent makers to show that "fast-packing" option, using just the fly and its footprint. Which actually may not be a total trick. I've done it in order to reduce a 2-man tent to an acceptable solo weight.
Carving your own footprint out of tyvek or whatever is a much cheaper go, and I got so far as to sew grommet loops onto my homemade one, so even the home-made version can be used together with the fly alone. Now I'm thinking of making one for our 2-man tent that has fabric, cloth upon the vestibules, since it's nice to have a clean spot there sometimes, you will have extra rest space if it rains.
2 ml painter's plastic, cut to "just under" tent floor size...but not for the many reasons already posted. It used as an extra vapor barrier, if I go without an extra layer as barrier, the underside of my tent is often muddy in the morning from condensate of ground water and fog moisture. Drying the tent bottom then means that I have got to turn over the tent, bottom up, in the sun...costs an additional 20 minutes to the morning pack up and get going ritual. Using the ground sheet footprint, you can pack up the tent (and everything else) without waiting. My (now dry) footprint then goes in the backpack very last thing/ first thing out too when at a new campsite. Also, when the footprint gets dirty and muddy, it's much easier to clean it up than clean up a tent.