Can You Have a Sleeping Bag In A Bivy?

I recently purchased a Winterial bivy sack. Since then I have found out through overnight backpacking trips that sleeping in a bivy is a symphony of adventure, challenge, and the occasional unexpected shower. My biggest issue has been how to make sure I am warm enough sleeping in my bivy sack. Does a sleeping bag and bivy go together?

Sleeping Bags And Bivy: A Holy Matrimony

A high quality sleeping bag is one of the easiest ways to make sure you are warm inside your bivy. Lay down a ground tarp under the bivy to help yourself get even more insulation.

Then, consider layering up inside your sleeping bag. Sleeping bag liners can completely transform your night experience.

How Much Does A Sleeping Bag Augment Your Bivy?

Overall a bivy helps you more in terms of keeping you waterproof and windproof. In itself it does not provide much warmth or insulation. Overall a bivy adds about 5º-10º heat to your body warmth.

Double wall bivies like the Winterial help you a lot with avoiding condensation. Not getting wet from your sweat during the night is key to waking up warm and well rested.

How Much Warmer Is It To Sleep In A Bivy Compared To Open Air?

Wrapping yourself in a bivy can up the cozy factor by about 5-10°F, a welcome boost when the night’s breath turns frosty​​. This warmth gain is the silver lining for adventurers braving the cold, a testament to the bivy’s ability to trap heat and fend off the chill.

Can You Make Your Bivy Warmer And More Waterproof?

The art of staying warm in a bivy is akin to brewing a perfect cup of wilderness tea—it’s all about the right mix of ingredients. Start with a high-quality sleeping pad, because ground chill is a real party crasher.

Consider layering up inside your sleeping bag. I have a friend who swears by the transformative power of a sleeping bag liner, pushing the boundaries of their 30-degree quilt​​. I suggest you check out the Litume all season sleeping bag liner.

Ventilation is key to combating condensation. Choose a bivy that has a double wall. Or smilarly one that has a small breathing hole. Opening a tiny gap can make a significant difference, letting moisture escape without inviting the cold in. Think of it as fine-tuning the climate inside your micro-shelter for a drier, warmer night.

Here’s a compiled list of tips to make your sleeping bag and bivy more waterproof and warmer:

Making Your Sleeping Bag And Bivy More Waterproof

1. Seam Sealing: Apply seam sealer to all the seams of your bivy sack to prevent water from seeping through. Sometimes it is good to do this at the beginning of the camping season. The bathtub floor and its connection to the wall of the tent is probably the biggest risk factor in terms of waterproofing..
2. Waterproof Spray: Use a waterproof spray on the outer fabric of your bivy sack. This can help repel water and keep you dry during rainy nights. I recommend the Nikwax waterproofing spray.
3. Protective Tarp: Set up a lightweight tarp above your bivy sack as an additional barrier against rain and snow. This will also help reduce the condensation inside your bivy by improving airflow.
4. DWR Coating Maintenance: Over time, the durable water repellent (DWR) coating on your bivy sack may wear off. Reapply DWR treatment periodically to maintain its water resistance.
5. Choose the Right Site: Set up your sleeping bag and bivy in a location that’s naturally protected from rain and runoff. Avoid depressions where water may pool and opt for sheltered areas under trees or rock overhangs (while being mindful of safety).

Making Your Bivy Warmer

1. Insulated Sleeping Pad: Use a high-quality insulated sleeping pad to reduce heat loss to the ground. The pad’s R-value is a measure of its insulating power; the higher, the better.
2. Sleeping Bag Liner: Add a thermal sleeping bag liner inside your sleeping bag to increase warmth. Liners made from silk, fleece, or thermal synthetic materials can add several degrees of warmth.
3. Wear Warm Clothing: Dress in layers of warm, moisture-wicking clothing to bed. A thermal base layer, insulated jacket, warm socks, and a beanie can significantly increase your comfort level.
4. Chemical Warmers: Consider using chemical hand or foot warmers for extra warmth during particularly cold nights. Place them inside your socks or pockets but be cautious to avoid direct skin contact for prolonged periods.
5. Close Gaps: Make sure your bivy sack is fully zipped up to trap body heat, but leave a small vent open to reduce condensation. Positioning the opening away from prevailing winds helps retain warmth while minimizing moisture buildup.
6. Bivy Sack with Insulation: Some bivy sacks come with built-in insulation or reflective materials that can help retain body heat. Investing in one of these can offer a warmer sleep system with minimal bulk.
7. Eat a High-Calorie Meal: Consuming a high-calorie meal before bed can help your body generate extra heat throughout the night, keeping you warmer.

By implementing these strategies, you can significantly improve the waterproofing and warmth of your bivy sack, making it a more reliable shelter in a variety of conditions.

The Risks Of Sleeping In A Bivy

Every adventure has its shadows, and in the case of bivy sacks, it’s the dual specters of condensation and confinement.

There’s the space—or the lack thereof. If the thought of being swaddled tight enough to make a mummy claustrophobic gives you pause, you might want to think twice about sleeping in a bivy. This is why you can’t get really big sleeping bag for your bivy.

How To Dress For Warm Sleep In A Bivy

Dressing for a night in a bivy is like layering for a day on the trail, but with a bit more strategy. A wool base layer is your first line of defense against the cold, capable of keeping you warm even if it gets damp​​. Add a breathable, insulating layer on top, and you’re setting yourself up for success. And don’t forget your feet—wool socks or even a chemical toe warmer can make all the difference when the temperature drops. I personally used these compression socks – they are a game changer!