[quote=Frankie]I need to cover the "shelter group" in my 72 hours evacuation and shelter-in place kits.

What is the reason behind the 5:6 ratio (8' × 10' and 10' × 12') instead of square most poly tarps at hardware and camping stores come in?

Thanks
Frankie

I believe the odd number is because of the number 5 as in the material is cut in 5' wide strips. At least it is with sil-nylon and presumably other nylon. This tidbit of information came from a small market tent maker. It should have a at least one seam if it is an 8x10 or 10x12 sheet. Also a rectangular size is usually more versatile than a square sheet with more variations on how to set up despite the examples shown it that tarp tutorial.

I've got 3 sheets - a 10x13 (yes that's an oddball size) ripstop poly, a 6'x8' lightweight silnylon tarp (with a 4' seam) and a 10' wide roll of 2 mil painter's plastic. That not counting my 2 tents. I find having some sort of extra tarp is handy when setting up camp in the rain - the extra square footage of rain cover serves to make supper in comfort.

Plus - think outside the box - think of that plastic shower curtain hanging up in that bathroom that is about 6'x7'. Leftover tyvek building wrap also makes a good tarp. Large contractor or orange garbage bags cut along the seam will open up to a nice size. There is no reason to limit yourself to store bought conventional tarps. Cordage wrapped around the edge of tarp with something small and solid like a pebble will serve as a tie out point. Grommets are not necessary - just conventional.

Thanks everyone for sharing your ideas and suggestions. Yes I've seen the pebble trick somewhere.

I thought about using a GI type of poncho with grommets and snaps after watching Michael Blomgren's videos, I'm just not sure where to buy it. I will check out my local military surplus stores.

The idea of matress sleeves is interesting and will consider it.

Frankie

No silly, the reason for the non-square size ratio is so it will look better, just like all them new tv sets.

BTW I have another question. Do you know what tarp (or alternatives) material that withstands extreme colds better, without cracking? What about 18oz UV treated vinyl tarps (that will probably cost too much)?

Thanks
Frankie

Cotton canvas is the most freeze/fracture resistant I've ever used.

Cotton canvas will also take long-term UV exposure MUCH better than synthetics. That's why Scout camps still use canvas wall tents rather than synthetics.

There's still something really nice about canvas tents IF they're allowed to breath (no mildew), but they are heavy.

If you're planning a long distance walk, then nylon gives you the best shelter for the least weight.

Otherwise, woven poly is the way to go IMO. Cotton is too darn heavy and too darn expensive.

Avoid the cheapo blue tarps (or equivalent lightweights). They're junk. Go for the midweight tarps with UV inhibitors. I have used the translucent ones and the silver ones with great success. No need to send away for these: a decent hardware store should carry what you need.

The toughest poly tarps I've every used are the industrial covers made by Integrated Plastics (IP). I've had a dark green one out in the sun for three years now and it's still intact.

Don't worry about cold weather. I've used woven poly for 20 years and have never had one fail due to the cold. It's the sun that eventually breaks them down.

i never understood why anyone would want a tarp in a kit that was large enought--pack size--when a small tent could be used..a tent has four walls and a floor and will keep out the rain and bugs while a tarp is open all around..i camped under a tarp on several two week canoe trips and found that a small cheap tent was much better..putting up a tarp is a lot of work while a tent is a few poles and stakes..you can use a tent as a "core" and pile brush around it if you need to keep off heavy weather..a tarp is a throwback to the days when you put one over an open fire..no small camp stoves..a tarp is a back-up item if your stuck for real shelter--so take a real shelter in the first place..
the cheap plastic tarps found in the big box stores make alot of noise in the wind--enought to keep you awake..they will stand up to sub zero temps..i have covered canoes and wood piles in Minnesota winters but don't expect anymore than a couple years out of them..if i were to get a tarp i would go for the lightweight canvas ones i recall from Scouts..wind and waterproof and heavy enought not to flap in a light wind and not burn thru with small sparks..

I like sleeping under tarps. But if the bugs are bad I add a mesh inner tent. There's no question that a full tent is warmer. And if there's a serious deluge a good bathtub bottom can save your bacon. I guess I just like to look out at the night.

Regarding the OP: If I understand correctly, the "shelter group" that's being referred to includes a dome tent, sleeping bags and pads, and tarps.

I don't do ultralight, but I have tried a lot of different ways to secure all kinds of tarps, from heavy canvas to the (throwaway) polyeth woven tarps, and these are by far the best way to secure any tarp in the worst conditions you would try to use a tarp in:

http://www.grabbittool.com/catalog/product_info.php?products_id=28

I've tried the through grommet style, the gripclips, the gator clips etc. These here are far superior. They are a lot bigger and bulkier, but they will get the job done.

After shredding three big poly tarps on a hilltop one fall day using rope all sorts of other fasteners, I ran to the sporting goods store and grabbed a couple 4 packs of these and had a tarp up that stayed up through the winds I'd guess at 25 mph consistently for almost two days before it subsided. That last tarp stayed tight and didn't rip out anywhere.

Now I have a box full of these 4" grabbit tarp holders, and another box of these:

http://www.grabbittool.com/RockBuster/RBHome.htm

They too are not ultralight friendly, but I know they work, and work well. I like to use what I know works, and I prefer these to making my own rebar tent stakes, which were truly brute force stake material.

As for whether to use a tarp vs a packable tent, I prefer a little luxury, and a tent is going to afford more comfort under most conditions than just a tarp. I will usually deploy both, using the tent as the sleeping area and the tarp to keep stuff off the head in camp while cooking etc.

Then again, I don't mind packing a 60 lb backpack when I do that sort of camping. YMMV.