I currently wear a Polartec Power Dry base layer and a 60g Primaloft One insulated jacket. This keeps me warm all the way down to about -10C when active(walking/hiking/Cycling).

At temperatures below that would layering another primaloft one insulated jacket be recommended or would it be best to replace the existing jacket with one of greater insulation.

In other words does 60g layer + 100g layer = the warmth of one 160g layer?
Or is it recommended to remove the first 60g and replace with ONE 160g jacket?


In my opinion two layers with say 60g/m² and 100g/m² are better than one with 160g/m². The different distribution of isolation is a point but I don't think this is relevant. You can get jackets with all kinds of stuffed torsos/arms/backs/arm-pits in lots thicknesses.

The big advantage of the layering besides the versatility is the caught air between the layers. This air is your best friend. Because of the very low thermal conductivity it gives you a perfect isolation and therefore protection against temperature gradients.

The downside is the bulkier design but the overall isolation should increase if you aren't wearing over-equipped (too many pockets/zippers/gimmicks) and therefore heavier stuff.

  • Thanks for your answer, the more I read it the more pros I see to having 2 "lighter" layers. It was your explanation that helped open the door so thanks! – AM_Hawk Dec 17 '13 at 14:32
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    I disagree with you on where the air gets trapped. For any insulating layer air is trapped inside the layer, not between any two layers. – Felix Dec 17 '13 at 19:13

Yes, you can always add layers to stay warmer. Exactly how much warmer isn't really possible to figure out, as different jackets put their insulation in different places (e.g., more in the torso/arms/hood).

Using multiple layers has the benefit that you can take off only some of your insulation if you are getting too warm (for example, if you start hiking up hill) and add some insulation back when you get cool (stop moving).

The downside is that two layers are heavier than one for a similar amount of insulation.

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