Zipper size for one person bivy tent?

[domonic]

What zipper size should I use for a 1 person bivy tent? I'm in the process of making one.
I wanted to use a size 3 zipper but I feel it could be too small and weak. #5 almost looks too large and heavy and finding something in between
is difficult.

Any clues as to what is the minimum zipper size I can get away with? Anyone used a #3 on a tent before?

Thanks.

[Mark F]

There is an unusual zip size being #4.5 but it is not a lot smaller compared to #5 and it will be very hard to source in Australia. Generally #3 is used on inner tent doors and is used on many tent flys as well. It does have durability problems in the long term with the zip slides tending to wear but these can be replaced. A bit of thought in how the zip is installed can make this job either quite easy or ridiculously hard. As the bivvy tent is quite small I would go with the #3 unless the zip is going to be subjected to high forces.

[andrewa]

I’d use a number 3, esp if home made, as you’ll know how to replace it should it ever come to that.

A

[domonic]

A number 3 it is. I think that's the minimum I'm game to use inside and outside. I notice that the average 2 man tents use a 5 but they're bigger. I'm sure I've seen a 3 on the flynet door.

Thanks for the help!

[andrewa]

Um...I wasn’t aware that there was a zipper lighter than a #3.

Remember that anything commercially made is going to be over designed, to reduce the risk of warranty repairs.

So, home made stuff can be made a lot lighter, as you know where the limitations are, you can be careful to minimise problems; there is no expectation of warranty repair, and you know how to repair the gear , as you put it together in the first place.

A

[domonic]

Agreed.. I think there must be a zip lighter than 3 but I was using a 5 and when both the mozzie net and outer door was finished on a previous tent I tried to make, the door side was getting pretty heavy. So #3 seems like the best option.

[Mark F]

You can get a #2 coil zip but like the #4.5 it is a specialty item and not generally available for diy The standard sizes are #3, #5, #8 and #10.. https://www.ykkfastening.com/products/search/detail.html?pdid1=Coil+Zipper+Standard
On the YKK site there is also a useful reference for understanding zip lengths if buying readymade zips. https://www.ykkfastening.com/products/zipper/s_zipper.html