How to Use a Tarp as a Rainfly

A rainfly is used in two different situations to keep campers dry. One involves the trend of sleeping in nature in a hammock. The other helps keep you dry when you’re in a tent. How does a rainfly help?

When you last went camping, did condensation build up inside the tent? You didn’t have air vents open to allow respiration and body heat to escape. Instead, the tent traps the moisture. It’s an unpleasant way to wake up. Yet, if you don’t close the air vent, a surprise rain shower soaks your bedding and pillows.

There’s another situation where a rainfly saves the day. You’re not using a tent. Instead, you’re sleeping in a hammock and have your top and underquilt to keep you warm. Imagine waking up to a sudden downpour. While sleeping in a hammock is comfortable, you’re exposed to the elements.

The Purpose of a Rainfly

A rainfly is a waterproof cover that goes over your tent or hammock. You’re protected from the rain, but you still have the ventilation that’s needed to keep condensation from building up. It fits over the tent or hammock to provide a waterproof cover. Yet, the ventilation in the tent isn’t closed, keeping you dry all night long.

Sometimes, your tent or tent hammock comes with a rainfly. You may find the brand you’ve purchased lacks that important component. If it doesn’t, learn how to turn a tarp into a rainfly that fits your needs.

Choosing the Right Type of Tarp

When choosing the type of tarp, you need to look at whether the tarp is water-resistant or waterproof. It does make a difference. Water-resistant tarps will provide some protection against rain, but if the rain is hard enough or goes for days, the water may start to work its way through. Waterproof tarps offer full protection against heavy rain. Here are the different options that work for a rainfly.

Water-Resistant Tarps:

A water-resistant tarp is one option. It’s best for camping trips where it’s not expected to rain. If there are any pop-up showers, they’ll be brief and end after a few minutes.

#1 – Canvas Tarps

Canvas tarps are water-resistant. The oil and wax coating goes over the cotton canvas, which creates a breathable tarp that keeps out some water. The problem with these is that that oil and wax coating can stain items that sit under the tarp. While they may make for a good cover for your campsite, you might not want your tent to get stains.

At Chicago Canvas & Supply, canvas tarps come in 16 and 18-ounce weights. Purchase them pre-sized in measurements ranging from 5 by 7 feet to 30 by 30 feet. The 16-ounce canvas tarps come in five colors, while the 18-ounce tarps come in olive drab. Custom sizes are available.

#2 – Poly Tarps

Poly tarps are made from polyethylene, which is a plastic polymer commonly used to make beverage bottles, plastic bags, and plastic film products. There are blue poly tarps or heavy-duty poly tarps. You’re probably familiar with blue poly tarps, as they’re the affordable tarps you see in discount stores. They’re not built to last.

A heavy-duty tarp is a better choice for a rainfly. It is important to keep in mind that they’re only water-resistant. They are UV-treated to protect against damage from the sun.

Custom sizes are not available. When shopping for poly tarps, your choices are:

  • Blue Poly (Sizes of 5 by 7 feet to 100 by 100 feet)
  • Brown Green Heavy Duty Poly (Sizes of 12 by 20 feet to 40 by 60 feet)
  • Camouflage Poly (Sizes of 6 by 8 feet to 16 by 20 feet)
  • Green Silver Heavy Duty Poly (Sizes of 8 by 10 feet to 30 by 50 feet)
  • Silver UVR Heavy Duty Poly (Sizes of 8 by 10 feet to 30 by 50 feet)
  • White Heavy Duty Poly (Sizes of 10 by 12 feet to 40 by 60 feet)

Waterproof Tarps:

When you cannot have your tent or hammock getting wet, a waterproof tarp is the best bet. We recommend waterproof tarps over water-resistant ones. If a sudden downpour hits the area where you’re camping, you don’t have to worry about water seeping through. Here are the choices for waterproof tarps.

#3 – Clear PVC Tarps

Would you ever want to use a clear PVC tarp as a rainfly? It depends. If you plan to sleep out under the stars, a clear PVC tarp allows you to actually see the stars while still being protected from any sudden rain showers.

Clear PVC tarps are waterproof and avoid damage from abrasion, rips, and tears. They’re also UV-treated. Keep one thing in mind if you decide this is the best rainfly tarp. As soon as the sun rises, that sunlight is going to come through the tarp and into your tent or hammock tent. If you hate waking up with the sun in your eyes, you may want to think twice about a clear PVC tarp.

Purchase clear PVC curtains in sizes ranging from 6 by 8 feet to 10 by 12 feet. Custom sizes are available.

#4 – Iron Horse Polyester Tarps

This is the best rainfly tarp you’ll find. It’s more durable than canvas. It’s waterproof and breathable. And, the silicone-coated material lacks the chemical odor that many plastic or vinyl tarps have. If you put it over your tent or hammock, you won’t be breathing in smelly fumes all night.

Iron Horse tarps are available in seven colors. By them in sizes ranging from 5 by 7 feet to 30 by 30 feet. Custom sizes are available.

#5 – Vinyl Coated Polyester Tarps

Vinyl coated polyester tarps are both waterproof and treated to protect against damage from the sun’s rays. Over time, sun exposure can dry a tarp and lead to cracking or fading. The UV treatment on a vinyl-coated tarp protects against this damage.

This is a great choice for a rainfly. Mold and mildew will not create an issue with the tarp rotting. They resist abrasion. They’re suited for both extremely hot and bitterly cold temperatures, making them perfect for year-round camping trips. Buy them in custom sizes or in sizes ranging from 5 by 7 feet to 10 by 20 feet.

How to Size a Rainfly

How do you choose the right size? Ultimately, the tarp size depends on your goals. Do you want a rainfly that covers the top and all sides of the tent? Do you want a rainfly that goes all the way to the ground or halfway? Once you know what you want, you’ll know how to measure.

If you have a tent hammock that’s 6 feet long and you want the rainfly to extend a foot past both ends, you’d need an 8-foot long tarp. Plus, you need the width. If the hammock is 3 feet wide, you’d want a tarp that’s at least 5-feet wide to extend beyond the hammock.

The same is true of the tent. You need the rainfly to cover the tent and go as far to the ground as desired on each side. Say you want a rainfly that covers the roof and adds a canopy at the tent’s opening. If you have a 6 by 8-foot tent, you want a rainfly that covers the 6 by 8 area and adds a few feet at the front of the tent.

Other Points to Keep in Mind

How do you plan to secure your rainfly? Grommets are usually spaced at least every two feet. If you’re using cord and tent stakes, make sure you have enough cord to secure the rainfly to the stakes. If you’re tying it to the tent or to trees, make sure you have a strong, waterproof cord. Braided poly cord is both mildew and UV resistant and has a 300-pound break strength. It’s a good choice for a tie-down that won’t rot when exposed to rain.

Tarps at Chicago Canvas & Supply are often available in custom sizes. This makes it easy to get a tarp that matches the size you need. Before you place a custom order, make sure you’ve measured the top and sides of your tent correctly. You don’t want to have mis-measured and end up with a rainfly that’s too small.