Choosing pit zips and how to sew them in

quest outfitters sells uretek #3 zippers by the yard

In terms of process, check out this step-by-step thread: (thanks to Link for pointing me towards it back in 2014!) https://backpackinglight.com/forums/topic/27921/

I’m a huge fan of pit zips – it’s one of the things that led me to The Packa.  I wouldn’t stress too much about either seam-sealing or having a waterproof zipper.  Unless you regularly hike with your arms above your head (i.e. climbing) with the pit zips closed you won’t have an issue with water getting in.

For me – it’s much more important that I be able to easily open and close the pit zipper without having to remove my jacket.  With that said – I can’t think of a time I put my Packa on where I didn’t open the pit zips at least halfway.  I just generate too much heat while hiking otherwise.  I do typically keep them closed until I put the jacket on because otherwise I find it really clumsy to put on (my arm keeps going through the open pit zip).  That could easily be a user issue on my end as well.

I have a jacket with pit zips and they never seemed to do much.  Opening the front zipper helped a lot though if it’s not raining with the wind blowing it inside.  But…

Since the zipper is facing down, it doesn’t need to be waterproof.

Since you’re unzipping the zipper for ventilation, it makes no difference if it’s waterproof.

The pit zip on my jacket is not waterproof.

Would it be easier then to just have two slits than trying to put a zipper in?

Brett – I have a custom Packa and actually thought of doing just that:  A long hemmed slit in each armpit with a small velcro tab in the middle in case I ever did want to mostly close it.  This post reminded me that my earlier statement about always having the pit zips wide open was not entirely correct:  When I’m in camp and am no longer hiking I’ll typically close the pit zips if I’m getting cold.  It’s the only jacket I carry so it becomes my camp outer layer if I need it.  That’s why I went with the zippers – I didn’t want to be wearing the jacket in windy 20-degree weather and losing all of my heat through flapping pit zips.

Slight derail but I used to have a jacket from Luke’s Ultralight (big sigh) that had pit zips that started in the armpit and went far down the arm to around the elbow. His rationale for this placement is that opening up the torso doesn’t work well with backpack straps so it makes more sense to ventilate the sleeves. I found this approach to be very effective.

None of this applies to The Packa, which floats over the backpack straps.