I'm trying my hand at building a set of carriage doors for my shop. They doors go in an opening 96" wide and 84" high and are divided into three panels, each about 32" wide. To reduce the room require to swing the doors two of the panels are to be hinged together (like a bifold door). Each panel will weigh about 100 pounds.

My original plan was to use four heavy duty butt hinges per panel and to space them out evenly. But, a few days ago I saw a similar (but two panel) set of doors in a door maker's display where the hinges were arranged with three hinges in the top third of he door height, with a fourth hinge at the bottom.

So, I'm wondering, are there advantages to putting most of the hinges near the top? It does seem like that would provide more fasteners to resist the load on the upper hinge(s) -- which I assume are taking most of the twisting load of the doors.

I've been using continuous hinges for 40 years as a commercial/ industrial steel and aluminum entrance sales and repair and as locksmith

There are several but my go-to is Roton, they make one for any circumstances.  I stock around 10 different in aluminum and bronze.  Mayflower Sales/Quality Hardware.

Look into the spacing recommendation that SOSS hinges provide in their instructions. They sound very similar to what you are saying. They have put a bunch of engineering into the point of supporting the weight of the door.
I don't remember it exactly, but it's based on percentages of distances from each other.
The "old fashioned" thing of putting a 3rd hinge in the middle of a door is not intended to support the weight of the door. It is actually there to control the potential of the door to bow one way or the other.

This is how SOSS says to do it. I have followed their recommendations up to the point of 5. I've never put 6 hinges on the same door.

The doors on the local hospitals x ray room only have four 4" ball bearing fire rated hinges and the doors are lead lined.l
Yer overthinking this.

Quote from: demographic on June 22, 2022, 12:32 PM

The doors on the local hospitals x ray room only have four 4" ball bearing fire rated hinges and the doors are lead lined.l
Yer overthinking this.

I've been known to do that... Thanks for the data point -- are they equally spaced?

I honestly can't remember but I do know they were a four man lift.
Even the backmolds were leadlined as well.

Just follow up, the doors are hung and looking pretty good. I used four 5" Hager heavy duty ball bearing hinges on each door panel. I spaced them using the SOSS layout mentioned above. No sign at all of sagging and the center section is solid and stable.

The accusations of over-thinking and over-engineering were probably fair