Rainfly Materials: Silnylon vs Silpoly

This post is the product of me getting way too in the weeds on my camp gear research. It might be true that I’m the only person asking about the differenced in silnylon vs silpoly is. As it turns out, it might make a difference in the type of rainfly you ultimately purchase. Understanding the differences between Silpoly and Silnylon may or may not matter to you, but if you’re really into Ultralight camping and backpacking, then you’ve probably run into these two terms. Here’s some helpful information that might help you choose the right rainfly.

Silnylon vs Silpoly

Silnylon and Silpoly are both woven fabrics that are used in tarps and rainflys for camping and hiking. If you’ve bought different rainflies in the past, you might have noticed that they come in all different shapes, sizes, and fabrics. Here’s how they compare across a few key categories. Expand each category below to read more.

MaterialWoven PolyesterWoven Nylon
Assume 20 Denier Thickness
DurabilityLess durable than the nylon.Strong, highly durable.
Water HandlingPolyester is hydrophobic and naturally repels water. The coating also helps.Nylon is hydrophilic and likes to absorb and rip water. Coating makes it handle water better.
StretchSlight stretch, good but limited placement and staking.Better stretch for a more convenient staking down experience.
SagStays taut regardless of temperature and moisture.Prone to sagging as temperature drops or rain falls.

As you can see, silpoly and silnylon each have their own advantages and disadvantages. Silnylon is is stronger and lighter for it’s thickness, but you’ll often find it needs to be thicker in order to repel water and hold it’s shape. Polyester, on the other hand, will probably not last you quite as long.

Rainfly Recommendations

Now that you understand the differences between silnylon vs silpoly rainfly materials, here are a couple quick recommendations for each:

SilNylon Rainfly

Silnylon vs Silpoly Rainflies

10×10 Chill Gorilla Hammock Tarp

I love this package because it does most of the thinking for you. This 10×10 SilNylon tarp weighs only 1.4 pounds (tarp only), which makes it perfect for backpacking. It also comes with lightweight guy lines and stakes, so you’ve got everything you need for your ultralight backpacking trip.

SilPoly Rainfly

Polyester Rain Tarp

Outdoor Vitals Ultralight Tarp

Of the two recommended tarps here, this is the lighter of them at less than 1 pound! The Outdoor Vitals Ultralight Tarp is a great SilPoly option. You can find this tarp in both 6 and 4 sides versions, and in a few different colors.

They also have options to upgrade to a 75D coated thickness for extra durability and protection. This adds a little weight, but still no more than the SilNylon version.

My Recommendation

After comparing the specs and advantages of SilNylon vs SilPoly rainflies, I think I’ll end up going with the 75D SilNylon rain tarp. It will be the perfect tarp to keep me dry on warm summer night when I’m camping in my Eno Doublenest.

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