I was thinking about this for a while. Why are common doors designed as they are today?

I'm particularly interested in the use of the door knob. I was thinking that it would be more useful and practical if it was located at the bottom and used with our feet. Like somewhat of a pedal design.

This way, our hands are free to carry more stuff when passing through. And you just close it with your heel on your way out. In addition, door knobs are used with all sorts of hands, making them dirtier than all sorts of things. No one ever cleans the door knobs. Ever.

And the lock, if needed, can remain to be used with your hands, using a standard key.

While the door handle for our hands seems more natural since we mostly rely on our hands when it comes to tools and technology, this seems like a smarter design. Despite that, I haven't came across this kind of doors yet.

Why would we choose the hand-knobs over feet-knobs, other than the tradition (which seems to be the reason behind it)?

This is actually connected to my idea of finding the best door design that relies purely on mechanical technology. No electronics or stuff, just pretty old rusty metals and gears. (Throwing something like the automatic eye-scan-lock, auto-slide doors out of the window.)

Are my pedal-doors superior enough over the classic doors, or perhaps for some reason actually not? Any ideas to enhance them? (Don't want to over-complicate it, simple & optimized for everyday life is good enough.)


closed as off-topic by Mołot, Azuaron, Youstay Igo, James, Aify Feb 24 '17 at 21:04

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about worldbuilding, within the scope defined in the help center." – Azuaron, Youstay Igo, James, Aify
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ This is very interesting question. Although, what level of mechanical technology? For instance, is nanotechnology allowed? I mean, materials made thanks to nanotechnology? $\endgroup$ – Pavel Janicek Feb 24 '17 at 13:33
  • $\begingroup$ Also, I did update a title a bit to make question feel more inside Worldbuilding scope. Hope you do not mind that edit $\endgroup$ – Pavel Janicek Feb 24 '17 at 13:35
  • $\begingroup$ @PavelJanicek Doors can vary. More expensive ones can include nanotechnology to enhance them, but I'm looking primarily on the common, not too expensive, everyday doors. Maybe a future version of the design, when nanotechnology is more common and cheaper, can implement that idea I think you have. $\endgroup$ – Vepir Feb 24 '17 at 13:46
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  • $\begingroup$ well in windy places you want to keep a hold of the door, or risk or the wall being damaged. $\endgroup$ – John Feb 24 '17 at 20:32

On top of kingledion's answer: you are assuming that all doors are opened by pushing, which indeed comes pretty natural with one foot. But try pulling a door with your foot: you won't be able to move aside and let the door open, because you have only one "free" foot (the other one is engaged in pushing the knob and pulling the door).

And don't forget that exercising force on a door on the middle of its side (where the hand operated knob is) equally distributes wear on hinges withouth adding additional loads.

  • $\begingroup$ Pushing from one side is pulling from the other... $\endgroup$ – a CVn Feb 24 '17 at 14:11
  • $\begingroup$ This is an even better and more obvious reason. $\endgroup$ – kingledion Feb 24 '17 at 16:01
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    $\begingroup$ +1 but doors that push both ways are quite common (and not suitable everywhere) $\endgroup$ – Chris H Feb 24 '17 at 16:26
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    $\begingroup$ The Lowes home improvement stores in the Dallas area have a foot grip on the main bathroom door for pulling the door open when you're done so you don't have to touch the door handle after washing your hands. It's actually quite easy and natural to pull the door open with one foot. So... -1 because it's actually easy to do? Random find from google: stepnpull.com not sure if that's the brand at Lowes. $\endgroup$ – JPhi1618 Feb 24 '17 at 16:32
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    $\begingroup$ @JPhi1618: I've seen bathroom doors with foot grip... is it just me having balance issues (the door was heavyish)? I don't find them practical, and I am relatively fit and able, I dread seeing an elderly, a pregnant woman or a child attempting it. $\endgroup$ – Matthieu M. Feb 24 '17 at 20:19

The mechanism for holding the pedal-door shut is at the bottom of the door. If it is not, then there is a complicated mechanism that transfers mechanical pressure at the pedal to a latch 2 feet up. This is more expensive and more prone to failure.

If you keep the latch at the bottom, this means that if you apply enough pressure at the top of the door, you gain a lot of mechanical advantage, and can possibly damage the hinges, or even gain entry. If the mechanism is in the middle of the door, as in our standard doors, there is much lower mechanical advantage.

I think that just normal wear and tear on a bottom-pedal door, whether bottom latched or middle latched, would make it mechanically unreliable enough that you would prefer a hand-opened door.

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    $\begingroup$ there is a complicated mechanism that transfers mechanical pressure at the pedal to a latch 2 feet up. This describes my front door. $\endgroup$ – frodoskywalker Feb 24 '17 at 14:11

You are absolutely right in that we build doors the way we do because we always have built them that way. Part of the reason for it is that it is one of those near perfect designs that you occasionally come across. Various answers have mentioned different aspects of what we consider a traditional door, and when taken together, you get a complete picture.

Here are some of the reasons why a foot latch is less likely to catch on:

How do you close it from the other side? You'd have to add a handle as grasping things with a foot is both difficult and awkward. foot-doors are only convenient for one direction of travel.

The latch is not in a spot that promotes security. I'm not talking about lock, security, I'm talking about accidents, wind, etc. Pressure against the top of the door will cause a shift that can reduce the life of hinges and let in drafts.

Anything you do to address the above adds to the complexity and therefore expense of the door.

I thought pocket doors that slide into a wall might be a solution, but you get even more complexity and less in flexibility of placement.

It would be easier, cheaper, and probably marketable to create a laser-robotic door knob cleaner.

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    $\begingroup$ Sometimes people do things the way they've always been done because they are unimaginative and blinded by tradition. But sometimes, often, things become "the way it's always been done" because doing it that way works and works pretty well. :-) As G K Chesterton once wrote, never tear down a fence until you know why it was put up in the first place. $\endgroup$ – Jay Feb 24 '17 at 17:49
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    $\begingroup$ In my daily work I often have to fight inertia and figure out a better way to do things. You wouldn't believe how hard this is (well, maybe you would). The door is a good example of something that was about the best design it could have. I also have to think about the story of the American space program developing a pen that could work in zero g environments, and the Russians opted for a pencil. $\endgroup$ – Paul TIKI Feb 24 '17 at 18:02
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    $\begingroup$ @PaulTIKI ...which isn't true. is it possible to use mechanical pencil instead of space pen in ISS? on Space Exploration has answers discussing both that, and the requirements for writing utensils that are to be used in freefall environments. (Pro tip: It's not zero gravity. If it was actually zero gravity, the space station would be on its way out of the solar system. It's a freefall environment in about 90% of Earth gravity.) $\endgroup$ – a CVn Feb 24 '17 at 19:02
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    $\begingroup$ I stand corrected on the microgravity point. Zero Gravity is a good way to explain free fall to the layman though. Even someone with very little scientific background can picture the environment The pencil thing is a good story too, kind of like Aesop's fables...not factually correct, but an easily grasp-able way to get a point across. Sometimes an old fashioned concept is actually the best way to proceed rather than expending time and effort on something that will also work but is hopelessly complex $\endgroup$ – Paul TIKI Feb 24 '17 at 19:13
  • $\begingroup$ @MIchael Kjorling is the mention of something as a story adequate to convey the potentially apocryphal nature of, well, a story. There are times when stories illustrate a point very well, and in the context of a short comment may work better than the pure science or math. I don't want to cause confusion. Is there an acceptable shorthand to indicate that something may not be objectively truthful, but might be used as a way to make a point? Should I ask this over on meta? $\endgroup$ – Paul TIKI Feb 24 '17 at 19:43

I remember that once I visited what you could call a "door factory". They created doors with interesting designs for different purposes: some of those for example where like bars embeded in the walls: the right one has got the even bars and the left one the odd. That allowed the door to be semi-closed so air and sun can pass throught it but a person couldn't.

It's not like we haven't tried to improve doors, most of the time it's because current design is the more convenient and less expensive.

From what I learnt from that visit I can guess why your design won't replace current doors easily:

  1. Cost: Having something to open the door (pedal) separated from something to lock the door (key) require 2 different mechanism to work together, therefore it will be more expensive. Also translating the energy from a pedal (you push it down) to the movement that will actually open the door (that needs to be applied in another direction) will require an aditional mechanism, that must de added to the final cost.

  2. The door could be open by mistake: If you are just passing by and accidentaly open the door without noticing it. Also, a dog/cat/toddler can activate the mechanism, so the door will be less secure.

  3. Accesibility: It will be a nightmare for disabled people or those in wheelchair.

There are different approaches to the: Don't use knob nowadays. For example, a bar in the middle of the door that once pressed releases the lock mechanism and allows at the same time the door to be open just with one movement. This way the only thing you have to do is press the door for one second and it will open, it's easy to use for disabled people, you can open it without you arms just by pressing it with your back and can even be activated by a wheelchair.


If a door needs to be unlocked (with a key, swipecard or code) the hand has to be used for that, even in your proposal. I suppose you could have very big buttons on the floor and tapdance the code to get in. If you get round this need for hands with face recognition, combadge detection etc., you might as well motorise the door as well.


A few design ideas that might make this feasible:

Your culture uses sliding doors rather than hinged. This eliminates the "opens towards you" problem and synergizes nicely with the following ideas.

The pedal is on the floor, not part of the door. The user steps on the pedal, which releases the latch in the opening side of the frame. This means you don't have to follow the door with your foot, which could prove difficult if you were carrying a heavy load. The user then either slides the door open with their foot or...

After the latch is opened, the door slides open due to counterweights. Mechanically more complex, and perhaps not for the average home depending on the level of technology and wealth, but nevertheless is a purely mechanical solution. To close the door, the user simply slides the door shut until the latch engages.

Regardless of design you come up with, the question becomes, Why? If you want your world to develop differently from our own, you should come up with some rationale. Here are some possibilities:

Germophobia - Who knows who last touched that doorknob?

Using your hands is ignoble - I'm not some plebian who needs to use his hands to do commmonplace task. I'd rather spurn this door with my foot.

Everyone has their hands full - Whether gesticulating prayers to the god of passage or just simply carrying all their work around, everyone's hands are too occupied for door handles.


I'll go against the grain here and say that yes, indeed, you can perfectly build a door which does require hands. I would not use a pedal either, though, as balancing can be tricky, especially while holding something complex in your hands.

If you've ever been to a restaurant, you should have noticed the kitchen doors. See that waitress with the loaded plates?

enter image description here

AP Photo/Ted S. Warren

She's got both hands occupied, so obviously she won't be using either to open a door. How is she going to do it?


Place your back against the door, and push the door with your back (and butt) as you slowly rotate around the door's hinges axis.

In really frequented kitchens, to avoid accidents, the doors will only open one way: one door to go in, one door to go out, so that two waitresses don't collide; it's also applicable to your case.

As for closing, it's automatic. You can use counterweights or springs, depending on your technology level, it's not terribly complicated to figure out.


First what comes to mind is the force needed to open such doors and that force impact on fragility of material used to create doors.
Door knobs and handles are located in the optimum place for ease to open doors and stability.
When you need to use doors with busy hand you install revolving doors, swing doors or just plastics curtains.


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