1200 vs. 5000 mm coating on tent floor

[skeeter]

I am cosidering buying a Big Agnes Emerald Mountain sl2 over the MSR Hubba Hubba, seems a big difference is the 1200mm on the Big Agnes compared to the 5000mm on the MSR. How significant is this factor in keeping water out of the tent? My biggest issue is staying dry, after that I want light weight, free standing, dble vestibule and at least 28 sq. feet insude the tent. I leave in May for my thru-hike (or get as far as I can w/ the time I have alotted) and am very appreciative of any advice I can get.

[Toolshed]

I am cosidering buying a Big Agnes Emerald Mountain sl2 over the MSR Hubba Hubba, seems a big difference is the 1200mm on the Big Agnes compared to the 5000mm on the MSR. How significant is this factor in keeping water out of the tent? My biggest issue is staying dry, after that I want light weight, free standing, dble vestibule and at least 28 sq. feet insude the tent. I leave in May for my thru-hike (or get as far as I can w/ the time I have alotted) and am very appreciative of any advice I can get.

I think it depends on the floor material - If it is simply taffeta nylon, then you would want a heavier PU coating. However, if it is silnylon, then I think a lighter coating makes sense - perhaps for longevity, which is what a I believe few traditional tent manufacturers have been doing when using Silnylon..

[bigcranky]

The numbers refer to a standard waterproofing test, how tall a column of water the fabric can take and remain waterproof. Basically, it's a pressure test (taller column = more pressure). So a 5000mm waterproof floor is pretty heavy duty. But a 1200mm waterproof floor is no slouch. However, if you apply other kinds of pressure, you can force water through the fabric -- for example, kneeling on the floor on very wet ground.

Either floor should be sufficient unless you want to set up on totally saturated ground (which is in itself a problem, since that is probably a low spot that will collect water in a rainstorm = you will get really wet. Gee, ask me how I know this.)

If you can lower your requirements a little, you can open up more choices. The Tarptent Double Rainbow meets your other criteria, and can be set up sort of free standing. If you are taking two people and use trekking poles, the SMD Lunar Duo is a great choice, though not free standing. Both are around 40-42 ounces total weight.

[Tipi Walter]

Tent floors are probably the biggest weak spots in tents other than UV damage to tent flies. When bigcranky talks about kneeling on a tent floor with wet ground underneath, well, no "good tent" should sponge up water thru the floor. Here's a test: Set up in a deluge and sit in your tent with an inch deep "lake effect pool and see if your tent floor leaks. Most 'sub-par' tents will leak somewhere, especially at the four corners or thru the floor where you are sitting.

Not to plug my tent, but Hilleberg makes one of the most bombproof floors in the business, and I've been thru all sorts of water and ground sheeting and little lakes with nary a drop of water coming in. Why? Who knows, but they use a triple urethane coated, taped floor seam, 100 denier, 7000mm whatever doodads but it all ends up to a dry floor.

TarpTents, Big Agnes, Hubbas, Seedhouses, Eureka Solitaire, Spitfire, you name it, they are for the most part using lightweight denier fabrics with low hydrostatic head whatevers and it all boils down to leak-prone floors when you set up on wet snow, wet saturated ground or in a small lake.

When the big boys like TarpTent or Eureka or Mt Hardwear or North Face advertise their tents, get suspicious when they don't mention the hydrostatic head or the denier of their floors. It's pretty important.

[stranger]

I think Toolshed is right...a standard nylon floor would require a heavier coating, because it's "water loving" side will absorb water - but on a silnylon floor, which is already highly water resistant, another 1200mm of waterproof coating is more than ample.

Tarptent for example uses just silnylon, no coating....and most users I know of haven't had many issues with water being forced through, so add another 1200mm coating and I think you're fairly good.

[skeeter]

Great information! I was at REI in Chicago this last weekend and could not get this question answered believe it or not. Sounds to me like the silnylon w/ a 12oomm coating should keep the water out. Thanks!

[RayBan]

Another thought: spray Niwax or its equivalent on the bottom/"tub sides" of your tent for additional porotection.

[butts0989]

Also if you can spare the room or space... either purchase some tyvek from the closest home depot to protect the bottom a bit more, or get a GG polycro ground cloth. Comes in packs of 2 and they each weigh 1.5oz. if you could seam them together it would be a great ultralight ground tarp costing only $8.