This leads to a bottleneck of people going in/out because there's only a single point to enter or leave. Not to mention potential stampede situation in the event of a fire. Is this just something we all see others doing so we figure, "Why not"?


3 Answers 3


Here are some potential reasons:

  • Security: It can be easier for staff to monitor who enters and leaves a store with a reduced number flow of customers entering the business.
  • Safety: To affect the draft flowing through a building. Have you ever had the experience of a door in your house slamming, because of a draft? A business owner may want to protect from a violently swinging door. An undesired draft could also have an effect on energy usage.
  • Not a regular door: Some double doors are installed for special use scenarios, such as needing to bring in a large piece of equipment, or needing to be open during an emergency. As part of these doors may be intended to only be used every so often, they do not operate like regular doors. Often time these kind of door will have latches that go into the top and bottom of the door frame. If unlocked some of these doors would just swing around. Due to this one of the two doors would remain locked.
  • Forgetfulness - Sometimes people just forget to check to make sure all the doors are unlocked.

Regardless, having one locked door in a set of double doors is not user friendly. The building and its entrances should be designed so that all general use doors can be used. One thing a better building or door design won't help is forgetfulness on the part of the building attendant/staff.

Here is an example of a double door design that I think affords approrpirate usage:

Image of double doors, where on of the two doors is significantly larger

By making one of the two doors larger, it communicates to users that this is a utility door, and that you probably shouldn't try and open it. Another way of helping users understand that one of two double doors isn't intended for regular use is to remove the door's handle and push plates.

Set of door with only one door having a handle

There are many other other work-arounds, but the list could go on and on.

  • 4
    "From what I've read..." Have you got a link to this?
    – JonW
    Nov 14, 2013 at 16:11
  • I reworded the first line of my answer. The list of potential reasons were summarized from a variety of sites & forums. As with broad questions, there isn't really one solid answer for this one, thus a more general (and un-referenced) list.
    – ChrisK
    Nov 14, 2013 at 17:00
  • Broad questions should be closed, not answered. And, thus, it was.
    – Rob
    Jul 20, 2019 at 2:10

This makes several things easier for the business:

  • The second door usually doesn't have a lock and key. Rather it has a mechanism on the side of the door (usually both top and bottom) that needs to be engaged and disengaged.
  • Employees usually have experience with locks and keys, but often not with double door locks. They often have to be shown how these locks operate.
  • This makes the opening and closing procedures more complicated. You need employees on hand that can operate the second door for both.

Businesses are especially leery of the closing time procedure. They don't want to leave a door unlocked all night accidentally. As such, many business owners instruct that the extra door just remain locked.

Here is an article that complains about this from a usability standpoint in a situation where pull and push is not clear as well:

I’ve seen it many times before where double doors have handles on and one is locked:

  1. You try pulling the left door with no joy
  2. You try pulling the right door with no joy, believing both are locked you look puzzled
  3. Then you notice the “push” sign on the doors. You push the one on the right, (which is the one that really is locked) with no joy
  4. Then push the one on the left and hey presto, you’re out!

Business owners often don't think that the time and security risk to deal with the extra door is worth it compared to small frustration of the occasional customer. This could be an example of the business owner and employees not experiencing this frustration themselves because they get used to which door to use.

Many businesses try to lessen the impact of this on their customers by posting signs about which door to use. For example here is a humorous one from Funny Den:

use other door, this is the other door

From a usability standpoint, maybe double door locks could be redesigned. Ideally, the turn of a single key would lock or unlock both doors simultaneously.

  • And as the single-key solution would be a doddle to design and implement, including locking at at least three points on the opening edge of both doors, I wonder why it's not common. Nov 14, 2013 at 19:50

My girlfriend works in a shop where they have both double door open all the time, regardless of the weather. It's pretty much all to do with sales. There have been a number of studies done over the years, and my gf has done some studies of her own, that shut doors provide an obstacle for people. And weirdly - as much as it's only a door - that obstacle is enough for people to not casually wander in.

My gf shut the doors on a day she knows is normally a busy day - her sales almost halved.

The amount of casual 'wander in and lets just have a look' shoppers dropped dramatically, as did people with 'extra baggage' (e.g. prams, buggies, strollers etc), or weirdly, people in groups of 2 or more.

There may be other reasons cited, security, air flow etc - and they may all be valid reasons, but by far and away - it's a sales thing.

Think of the phrase "My door is always open", or "He's got an open door policy". Everything meant to be welcoming is where the door is always open for you, no obstacle. Lazy, but true.

  • 2
    This doesn't address the issue in the question - why one door is left unlocked and the other left locked.
    – JonW
    Nov 14, 2013 at 16:12

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