Reason elevator remained broken for all 12 seasons of The Big Bang Theory

There's a very interesting reason behind The Big Bang Theory's broken elevator, and why the writers didn't bother to fix it until the end.

The American sitcom ran for a total of 12 seasons from 2007 to 2019 on CBS, giving actors such as Kaley Cuoco and Jim Parsons their breakout roles on TV.

But along with its nerdy subject matter, The Big Bang Theory is known as one of the most beloved comedies of the 2000s, with tiny details that make it so easy and fun to watch.

One of these small details was to do with the broken elevator - or lift for us Brits - in Sheldon (Parsons), Leonard (Johnny Galecki), and Penny's (Cuoco) apartment building.

It's an ongoing gag that the elevator doesn't work, and as Penny and the two boys live on the fourth floor, we often follow the gang up and down the stairs while they have conversations about a number of topics.

The gag produced a number of memorable scenes, whether it be characters being forced to reconcile, a nervous Leonard running into Penny in the early seasons, or Sheldon bugging the characters with his eidetic memory.

Well, it turns out that the broken elevator was added on purpose to highlight more personal moments with the characters as co-creator Bill Prady revealed all at WonderCon.

Many hilarious scenes could come about organically as a result of the stairs (CBS)

"One of the things you need is a place for characters to walk and talk." he said (via Fandom Wire). "When Chuck Lorre and I had worked on Dharma and Greg we had this outside street set where characters could have a conversation. And we had it because it was an unused stage at 20th Century Fox where we shot Dharma."

Prady continued: "We tried to do that at Big Bang and it was just too much real estate and we started talking about, ‘What if they always had to walk up the stairs?’

Yellow caution tape could be spotted across the elevator from the pilot episode of the sitcom, confirming this train of thought.

In Season 3 Episode 22, titled The Staircase Implementation, it turns out that in an experiment gone wrong, resulting in an explosion after Sheldon places the apparatus in the elevator where it explodes, is the reason behind the broken elevator.

The conversations between characters in the scenes going up the stairs were often more casual too, and helped viewers connect more with them on a personal level, while building relationships between characters.

Who knows if Penny would have ended up with Leonard if not for those stairs?

It's almost as if the broken lift was another character on the show (CBS)

In the penultimate episode of the show's final season, the lift was fixed, with Penny popping up to the fourth floor in front of Sheldon and Leonard, to their shock.

Showrunner Steve Holland revealed to Entertainment Weekly that the revelation brought on a 42-second applause from the audience before Cuoco's line.

However, the stairs were not as loved by the actors on the show, as Kunal Nayyar revealed to the Channel 4 Sunday Brunch show (via The Independent) that it was tiring to shoot those scenes.

Nayyar explained: "The way it works is, you go down the stairs, and then they yell, ‘Hold.’

"They change the scenery from, like if the apartment says 1a, it suddenly says 2a or 3. They change the set so it looks exactly like another floor.

"You run back up the stairs, that go nowhere, and then you walk back down as if it’s a new floor," he revealed.

That does sound ridiculously long-winded, to be fair - but it's all worth it for us viewers, eh?