Do You Need a Groundsheet Under a Bivy Bag?

When to Use a Groundsheet

When camping in wet or damp conditions, it’s crucial to have a groundsheet under your bivy bag to prevent water from seeping in. In these situations, a lightweight, waterproof groundsheet can significantly reduce the risk of getting wet, making your shelter more comfortable and durable. Consider using a silnylon or nylon groundsheet, which can be easily staked out to prevent water from accumulating.

Alternatives to a Groundsheet

In dry environments or when every ounce counts, you can opt for other water-repellent alternatives to a groundsheet. A tarp or a space blanket can provide similar protection against water and wind. However, keep in mind that these alternatives may not be as effective as a dedicated groundsheet, especially in heavy rain or snow. If you do choose to use a tarp or space blanket, ensure it’s securely staked out to prevent water from pooling underneath.

Practical Considerations

When using a groundsheet under a bivy bag, consider the following practical considerations. First, choose a groundsheet with a waterproof rating of at least 10,000 mm and a UV resistance rating of 5 years. Second, ensure your groundsheet is large enough to cover the entire area underneath your bivy bag, with at least 6 inches of overlap around the edges. Finally, use stakes and cordage to secure your groundsheet tightly, preventing water from seeping underneath.