I owned, used extensively in all sorts of conditions, and then returned a Black Diamond Guiding Light [4 kids and two adults in that tent]. We loved that tent, except for the seam sealing, or lack thereof, on the floor of the tent. I understand that the Epic fabric on the top of the tent can't be seam sealed. There's no good reason that they can't seal the floor, however. And, the fabrics that they use and the way that they sew it together makes it very hard to seal at home. The fabric on the pole pockets is slick enough that it flakes off and has to be reapplied every 4 trips or so.

Anyway, I emailed them to ask if they were planning on seam sealing the tent floors in the future. This is how the conversation went:

Me -
Do you have any plans to start seam sealing the floor on the Guiding Light? I understand that you can't factory seal the Epic fabric on the top of the tent but you could do the floor and pole pockets.

Black Diamond -
Hi Justin, thanks for the email, unfortunately, the guiding light has actually been discontinued. We are coming out with a new fabric next spring called nano-shield that will be an improvement over the epic fabric, and the line will be super paired down (to like 4 tents). I believe the floors will still eb un-sealed though, and part of the reasoning is that to coat the whole floor and seam tape it would add a lot of weight to a super-light series. [I added the italics]

Me-
Weight that would have to be added to the tent anyway...only by an annoyed customer. Oh well, I guess I won't be buying another Black Diamond tent any time soon.

Black Diamond-
No problem, glad I could be of assistance.

So, Black Diamond's reason to not seam seal fabrics that can be seam sealed is to artificially lower the weight of their tents at the point of sale.

I actually don't mind seam sealing. It's usually not very hard. However, they are building tents where they leave a half of inch of fabric hanging out of the seam so that you have to seal both sides of every seam and make it so you have to seal the outside of the floor seam (which just collects sand - in dry silicon seam sealer), and they use fabrics that are sewn to silicone impregnated silicon, so that you have to use silicone seam sealer, which doesn't stick to the other fabrics well. When they are doing all of this, they are just building poor lightweight tents.

Really, are there any other big manufacturers that aren't seam sealing fabrics that can be factory seam sealed?