Home / Backpacking Skills / Clothes and Layering / Mechanical Venting, Pit Zips, and Layering

Mechanical Venting, Pit Zips, and Layering

Breathable Fabrics and The Emperor's New Clothes
Breathable Fabrics and The Emperor’s New Clothes

Are you sick of the exaggerated breathability claims made by outdoor gear manufacturers? Can you really afford to spend another $400 – $600 dollars on a jacket with the latest breathable fabric? Do you realize you are being played by unscrupulous manufacturers in a never ending game of bait and switch? Are breathable jackets only as good as the Emperor’s new clothes?

Introducing the Pit Zip!

If you want to stay dry in cold weather, get yourself a hard or soft shell jacket with pit zips that can be opened to vent off excess heat during high levels of exertion. Pits zips augment the breathable fabric in your existing jacket and prevent it from becoming overwhelmed when you really start to sweat. They also can eliminate the need to take off layers and help avoid added delays when you need to make tracks.

Pit Zip with Green Fleece Poking Out of It
Pit Zip with Green Fleece Poking Out of It

Called mechanical venting, pit zips typically run from underneath your elbow to the middle of your torso, where you sweat the most. Some manufacturers, like Outdoor Research, provide extended pit zips on their hard and soft shell jackets that run from the back of your elbow all the way to your waist, enabling a poncho-like effect that further accelerates the evaporation of sweat when opened.

Outdoor Research Torso Flow Pit-to-Hem Venting System
Outdoor Research TorsoFlo Pit-to-Hem Venting System

I think we have to give Outdoor Research some credit: they include TorsoFlo vents on jackets made with breathable fabrics, obviously because they understand the limitations of breathable technology. They’re one of the few technical apparel companies I know of that put vents on jackets made out of Gore-tex Pro and Gore-tex Paclite including the bomber Maximus Jacket and the lightweight Furio Jacket. I own an older model OR jacket with the TorsoFlo venting system and it works great.


Layering is even more effective than zippered vents because it enables you to release heat more quickly and prevent sweating.  It’s simple, dress like an onion in cold weather with multiple layers of clothing (click for KISS layering in Winter). As you start to sweat, stop and take off your outer layer in order to vent the moisture from the next layer down, and so on. It’s not unusual for me to strip all the way down to my base layer in 20-30 degree weather if I’m snowshoeing or hiking vigorously up a steep mountain.

Dress Like and Onion - Pinkam Lodge Ready Room
Dress Like and Onion – Mt Washington Ready Room

If you’re hiking with an experienced group of people, no one will object to you stopping to strip off a layer and stuff it into your backpack. All of the people in your group are probably heating up and cooling off at the same time you are and they’ll be relieved when you call for a “layer break.”

The Breathability Trap

So, the next time you feel like the urge to buy a jacket made with the latest breathable fabric technology, remember that low tech solutions like layering or pit/torso zips are more effective and cost far less. There’s a reason why jackets and rain pants with pits zips and side zippers like the Marmot Precip remain so popular after being on the market for so long: mechanical venting works and it’s far less expensive than the emperor’s new clothes.

Most Popular Searches

  • pit zips
  • pit zip
  • womens waterproof jacket with pits zips


  1. Buffalo are some of the best garments for venting and reduce the need for layering too. Love my Teclite shirt and I’m thinking seriously of getting either a Mountain Shirt or a Special Six Shirt

  2. Sadly the pursuit of breathable claims of waterproofs (I dispute the claims BTW) has focused on material over function for too long. Good venting is a “must”. Once you restrict the surface area of the jacket with a rucksack covering your back, and shoulder straps etc, there is less surface area to breath anyway.

    Off to look at OR jackets as I need one for this years walks. They look a sensible bit of kit.

  3. I don’t understand why more manufacturers don’t use venting pockets or pt zips. Cost and laziness I guess.

    • My guess is that it undermines the value proposition of using the breathable fabric and it’s high price. Most manufacturers probably figure that no one is going to pay for an expensive breathable fabric if it “has” to have big holes in it. And as you say, the manufacturer is more difficult because of the zippers.

  4. Interesting post, Philip. I just got me a shell with pit zips and have used it a few times this winter. Having never had pit zips before, I was surprised at how much of a difference they made. WIN!

  5. When I bought my first Goretex jacket, I also bought into the hype. It wasn’t long before I referred to it as my “Coat of Anger”, as I spent time, either getting cooked, or freezing. Sadly, I just didn’t know how to use the thing, and got rid of it. None of them work as advertised (at least for big sweaters like me), but some are better than others. I just avoid the ones with the rubbery coated insides, and I’m good. I also rarely use them. If I’m starting out on a big climb, and the temp is in the 40s, I wear a smartwool short sleeve, arm warmers, and a windproof vest. The vest comes off as the heat builds (hopefully before I’m sweaty), then the arm warmers slide down over my hands (they stay cold longest), until I’m down to just the baselayer. Once I’m up the mountain, I swap out my wet baselayer (fun in cold, windy weather), for a dry short sleeve, and possibly a midweight smartwool long sleeve. If I’m still chillin’, on goes the vest. Still cold? Then, it’s time for the jacket… I usually only use t when it’s really cold (29 or less), raining, or I’m headed down hill. The important thing is to know your own body, and adjust layers with the proper timing. If you wait until you are hot. You will be sweaty. Arm warmers are also “The BOMB” for hot hikers like me.

  6. Hrm, if only I had read this post a month earlier. I just sprung for the Marmot Zion made with the new NeoShell. It was on sale for $213, normally $385…so I thought that was pretty good. I’m hoping it DOES breath well, as that’s what I’ve heard from folks who have tried the neoshell technology. I’ll be sad if I could’ve just stuck with my rain jacket with pit zips over a fleece. :)


  7. Happy to have been an avid reader of this website before dropping money on gear. Based on your reviews, I purchased ( all on clearance sales) an EMS Helix hard shell ($86) an EMS Exodus Fleece ( $50) and a Marmot Super Mica ($77). All with pitzips. For just over $200, I have a versatile, four season setup for both dry and inclement weather. Prior to this, I had purchased a Marmot Nano ($99) – Goretex paclite but no zips. While I cannot say any of the hard shells have been given the acid test ( continuous heave downpour), there is no question the versatility of the zips has been very handy on my day hikes with the Exodus. I beleive this is still available at EMS for $50 ( a screaming bargain) and has become my go to jacket this winter.

  8. I’ve been using a jacket from OR for about 4 years and I love it. It’s made of the Goretex Paclite and has the full pit zips. I would highly recommend them. I have a habit of bringing rain with me whenever I hike and I can honestly say I love that jacket.

  9. Thank you. I bought a Marmot Precip years ago as part of my layering system and it has worked fine. I love to peruse gear, but honestly I don’t buy that much anymore. There are so many gimmicks, gadgets and new fabrics out there I would need a 10 liter pack and a huge wad of cash to re-outfit myself every year. My gear is like an exclusive club. Any new item has to run a gauntlet to get in. Even if something makes it, it could still end up in my obsolete gear box.

  10. If you have investing much in a jacket, you might consider adding the pit zips.

    When I first started hiking, I bought a good North Face insulated hard shell and early on realized it was too warm on fast hikes and too bulky to just have in my pack for breaks.

    A few years back I contacted Thrifty Outfitters and they could insert pit zips for $65-85. I have yet to send my jacket in, it just hangs unused in the closet, but I should. Adding would be cheaper than a new jacket.


  11. +1 on the benefits of mechanical venting!

    And a controversial idea on the layers: I’ve only experimented with this one season so still uncertain but insulated top layers with good mechanical venting might be very good for cold winter use, especially if moving and stopping a lot (guiding an inexperienced group, taking photos, etc.) Wear very little under the insulated top layer, open the zips while on them ove, close up when stopping for longer time. Works very well, unless the activity level is very high (breaking trail uphill in deep snow with a load).

    Plus, in my opinion there is quite a good selection of Goretex Pro jackets with pti zips. But unfortunately less with Paclite and even less with the new Active. I think this is more because of Goretex and not so much because of the companies manufacturing the clothing.

  12. Another thing that used to be more common, and is handy for fine-tuning your ventilation, is the double-ended zipper. Don’t see them much now, maybe because a) more expensive and b) jackets now tend to be cut shorter. Just dumb – it’s a good thing if a raincoat covers your butt!

  13. In the 90s, I had all top of the line Patagonia and it worked b/c I was young & fit. In the 2000s, living in the temperate rain forest of W. Washington State (120 inches annual), I learned from locals that wool is the way to go. I rely on Filson clothing a lot (tin cloth). But now I’m giving both a try with the addition of Gore-Tex Pro outer layers and the new Patagonia Nano-Air hooded mid-layer which claims a breathability breakthrough. Apparently a few years back, Polartec fleece had a breakthru with their Alpha insulated mid-layer. It allowed military folks to not sweat so much. Nano-Air claims to be just as good. I always get pit zips. Check out Steep & Cheap for deals as well as Patagonia Worn Wear. I usually break trail and am in constant contact with branches. So, Filson tin cloth works well plus their 100% wool. Call the Filson Outlets for deals on 2nds, they will mail it to you for free. On mid-layers, get a hoodie or hooded-version as there is always wind out there. This discussion about Gore-tex is a classic one in the camping field. Been going on since the 70s. Gore-Tex has sold a lot, but it has never won the argument. Living in a rain forest, the most valuable things are a dry roof and learning to stay dry in the field – no one has gore-tex. There’s birch bark or pine sap and not much else in nature. The issue is the nature of human beings and the fact that we always 24/7, even while sitting on a couch, have an invisible cloud of humid air around us. We perspire constantly in micro, micro amounts. This is all covered in the Army Arctic manual from like the 1900s written by the famous arctic explorer Stefansson. Before you can properly cloth folks, you have to realize that we’re always wet in the tiniest way. Probably why we need water every 3-4 days or we get sick. Like one of the other posts said, try to run your body just a little cold and you’ll find your pace. If it’s above freezing, make sure you have a good draft running up your legs to shed that heat. Dress like a park ranger, Filson wool whipcord pants rolled up or hemmed so that a draft gets up there – not long and touching your boot laces (until it gets colder). A lot of this is about patience & getting older and noticing what your body is doing. It’s pretty difficult!

Leave a Reply

Your email address will not be published. Required fields are marked *

Subscribe To Our Newsletter

Get a digest of the latest gear reviews and articles once a week. No spam. 

You have Successfully Subscribed!