Double-wall tent at a glance
- Layers
- Mesh inner plus waterproof fly
- Weight penalty
- Roughly 6 to 12 oz
- Condensation lands on
- The fly, not your bag
Why two layers keep you drier
A sleeping adult gives off roughly a pint of water overnight, and inside a small shelter that water has to land somewhere. It lands on whichever surface is coldest, which is always the one facing the night sky.
In a double-wall tent that surface is the rainfly, and the mesh inner holds it a few inches off your face and your sleeping bag. Brush the wall in the dark and nothing transfers. In a single-wall shelter there is only one surface, so the water collects on the inside of the tent itself.
What the second wall costs
Weight and packed size, mostly. The fly and inner together run about 6 to 12 ounces heavier than a single layer covering the same floor, which is why almost every Dyneema trekking-pole shelter is single-wall.
Single-wall is not a defect, it is a trade. It asks you to pitch with ventilation in mind, keep a vent open, and expect to wipe the walls down some mornings. Durston's X-Mid line is the notable exception that stays double-wall at ultralight weights.
What this means when you're choosing
- Whether the inner is mostly mesh or mostly solid fabric, which decides ventilation against draft protection
- Whether the fly reaches the ground or is cut short, since a truncated fly ventilates well and lets driven rain under
- Whether the fly can be pitched on its own, so you can set up in rain without soaking the inner
The common mistake
Pitching the fly tight against the inner
The gap between the two walls is the whole mechanism. Pitch the fly slack and it rests on the mesh, water wicks straight through the contact patch, and you wake up with a wet stripe down your bag. Tension the fly until it stands clear all the way round.
Common questions
Is a single-wall tent always wetter inside?
Not always, but it is less forgiving. The water has one surface to land on and that surface is inside with you, so ventilation and site choice matter far more. Pitch a single-wall shelter in a damp hollow on a still night and you will have condensation; pitch it on a breezy rise with a vent open and you may have almost none.
Can I leave the rainfly off a double-wall tent?
On a clear, dry night, yes, and it is one of the nicest things about the design. The mesh inner keeps insects out while you look at the sky. Keep the fly within reach, because a mesh body offers no rain protection at all.