Is grossgrain necessary for DIY rain fly edges?

[SilvrSurfr]

Not necessary, but some think it provides a tighter pitch. I just made a silnylon tarp using Fronkey's tutorial and have grosgrain reinforcements on the corners/tie-outs only.

[alexdickerson]

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.

[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.

[Hammonkey]

Its not necessary. I made mine with just a rolled hem around the edge and its held up just fine. I triple rolled the hem before i sewed to give it a little more strength, but grosgrain would be overkill and heavier.