Is grossgrain necessary for DIY rain fly edges?

[Mouseskowitz]

I've done it both ways. There may be some structural component to it, but I think it's minimal. In my mind it's an esthetics and weight issue. Since you're using PU 1.9 I'm assuming weight isn't an issue. You can always add the grosgrain if you don't like the results without.

[alexdickerson]

What size should I use? I'm looking at the 3/8" from Quest Outfitters.

[Klaussinator]

Why add something that isn't needed? Hemmed edge for me.
As Mouseskowitz said, you can always add it later if you decide you want or need it.

-Klauss

[alexdickerson]

How would you add it after if you've already done the tie outs and such? Sorry about all the questions, as you can tell by my number of posts, I'm pretty new around here.

[Floridahanger]

I'm a utilitarian type. I don't like the grosgrain look myself because it adds more than needed and with a rain it keeps the water from shedding properly down the side due to the raised edge it makes, it collects then rolls to whatever side is down angle.

I only used it for my tieouts. For me, a finished double-fold hem looks just fine, like a nicely made shirt.

[boulderv7]

What size should I use? I'm looking at the 3/8" from Quest Outfitters.

I use 3/4" from DIY gear supply.

How would you add it after if you've already done the tie outs and such? Sorry about all the questions, as you can tell by my number of posts, I'm pretty new around here.

You could still add it, but it would look added, unless you seam ripped your tieouts off, added the grosgrain, and then sewed the tieouts back on. I would either use it or don't use it. If its your first big project, and its all straight edges, I say skip it. It takes a little practice to bind it perfectly. If you are indeed using PU 1.9, a rolled hem on a long straight edge will be easy.

[dirtwheels]

I have a Warbonnet Edge without grosgrain on the sides, Wilderness Logics and Mountain Laurel Designs also produce tarps with hemmed edges. So it's not uncommon.

[SirMarkos]

I skipped the grosgrain on my DIY rectangular tarp. No extra weight and the double rolled hem looks/works perfectly.

My DIY Multicam Tarp

[Mouseskowitz]

What size should I use? I'm looking at the 3/8" from Quest Outfitters.

I would go with something in the 3/4" to 1" range. It's amazingly easy to not have it lined up and miss one of the sides even at that size.

How would you add it after if you've already done the tie outs and such? Sorry about all the questions, as you can tell by my number of posts, I'm pretty new around here.

As boulderv7 said, you could take the tie outs off. Or you could cut the ends of the grosgrain to be flush against your tie outs. If you weren't looking for it, no one would probably ever notice.

[zooshooter]

My thought is that I'll do the same, reinforce the corners with it, but that the coated 1.9 will give it some extra strength as opposed to 1.1 sil. Weight is no concern.

It's been shown that PU coated polyester or nylon material is weaker than silicone impregnated material of the same type. Theory being that the coating binds the threads of the material instead of allowing them to move. The reasoning behind it is still just theory but testing has shown that the tear strength on sil fabric is higher, sometimes more than twice as high, than PU coated fabric.