UKC

Idle chit-chat one night brought up the above quandary. I have a thin windproof which would be comfortable as an inner layer or practical as an outer layer. The question is, which is more logical, wearing it over the thermal layer to protect the trapped air, or under the thermal layer to protect body heat?

I have my preference, but what are the scientific arguments that puts one idea above the other?

In reply to wme:

Logic would be to wear on top?

In reply to wme:

Not scientific but personal experience. I've got on old Craghoppers fibre pile jacket which is both windproof and warm. It came with a windproof liner and so good that I haven't got rid of it even though it must be nigh on 20 years old now. In fact it's the zip which is knackered!

In reply to wme:

Both, if that makes any sense.

I find a thin, tight-fitting, wind-proof layer ideal for climbing, then I add an insulated windproof layer on top when belaying.

This means I normally have two windproof layers on when belaying on multi pitch routes.

In reply to wme:

pretty much by definition, the windproof layer should be the outer layer, where it can preserve body heat by stopping the wind dissipating the heat trapped by your thermal layer

In reply to wme:


Over, definitely.

The thermal layer ought to "protect body heat" - that's why it's a thermal layer! The thing that would make a decent thermal layer ineffective at keeping body heat in is a cold wind blowing through it, hence you stick a windproof over the top.

In reply to wme:

Two choices, giving different degrees of insulation...

If the windproof is under the fleece, it won't give much protection to the warmth trapped in the fleece (which, incidentally, is also body warmth).

With the windproof over the fleece, the warm air remains trappedin thefllece, so there's a thicker layer of insulation between your body and the environment, so you should be warmer.

In reply to wme:

By 'thermal layer', do you mean fleece? I suspect that non-windproof fleeces as outer layers provide minimal insulation. Insulation works by trapping warm air; if the slightest breeze can woosh through your thermal layer and blow all the warm air out, you'll bet getting precious little benefit from it. Windproof over the top of fleece, every time.

Happily, this is an easy experiment for you to perform next time you're out!

In reply to wme:

as a counter question - would you wear a waterproof under or over your thermals? Same logic

In reply to owena:

Thanks - fair to say you're all unanimous in your answers. Surprised no-one had a pop at what could seem a daft question!

In reply to wme:

It seems that Berghaus have thought about this with their Hyper Therm top that's coming out next year. It's reversible, insulated and uses two face fabrics with differing levels of breathability/windproofness so you can choose if you want more wind protection or more air movement through the insulation.
Suggests it's not such a daft question after all.

In reply to EvanDavies:

Reversible fleeces have already been tried maybe 20 years ago. The problem is that with the windproof layer inside (presumably because its warm), they feel very sweaty. Much better just to remove the windproof to adjust temperature.