The layering idea, stated properly#
The familiar three-layer slogan is not wrong, it is just incomplete. What actually decides comfort outdoors is the gap between the heat you produce and the heat you shed, moment by moment. Walking uphill under a pack, you may produce five times your resting output. Stopping for ten minutes, that drops almost immediately while your clothing stays exactly as insulating as it was.
Two consequences follow, and they run through every page in this section.
First, the layer you move in and the layer you rest in are different garments, with different jobs. A moving layer must dump heat and moisture; a camp layer must hold it. Trying to buy one garment for both is why people are simultaneously sweaty on the climb and cold at the top.
Second, moisture, not temperature, is what makes people cold. Evaporating a kilogram of sweat removes about 2,257 kilojoules of heat. Regulating early with zips, a hat and pace costs nothing and prevents the wet base layer that no amount of insulation fixes afterwards.
Where to start#
- The layering system for the framework and clo values
- Rain jackets and breathability for what the numbers on a shell mean
- Insulated jackets for fill weight against use case
- Footwear and socks for fit and blister prevention
Frequently asked questions#
Is merino better than synthetic?#
For odour resistance and feel next to skin, merino. For durability, drying speed and cost per season, synthetic. Both manage moisture adequately; cotton does not, and that is the only fibre choice that genuinely matters for safety.
How many layers do I need for camping?#
Usually four garments that cover every case: a base layer, an active mid layer, an insulated jacket for stops and camp, and a waterproof shell. Adding a fifth is rarely useful; swapping the mid layer for the conditions is.
Do I need waterproof trousers?#
In wind driven rain, yes, and they are the item most often left behind and most often missed. Legs lose heat quickly once soaked, and wet trousers under a dry jacket still carry water into the tent.
What should I wear to sleep in?#
Dry clothing you did not hike in, plus a hat. Sleeping in damp layers is one of the most common causes of a cold night, covered in why you sleep cold.