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Fun Facts About Commercial Doors You May Not Know

Commercial glass doors

Commercial doors aren’t exactly the hottest topic. For instance, there’s never been a blog about doors that will “break the internet,” and there probably never will be. Unless, of course, this is that blog, in which case you saw it here first. 

Here are a few fun facts about commercial doors that you probably don’t know: 

Big Doors

If you had three guesses to determine where the largest doors in the world are, you might be able to get this one right with little to no assistance. They belong to NASA. You probably saw that coming, and now you’re probably also imagining an Artemis rocket coming out of the hangar and rolling to the launchpad.

NASA’s big doors stand 456 feet high. For comparison, three times as tall as the Statue of Liberty. These doors are located at the Kennedy Space Center. Opening or closing them takes about 45 minutes, so if you want to go watch, you may want to pack a snack.

The Door Knob Is Really Old

We take for granted these days that commercial doors all have sleek and sturdy pulls, knobs, or crash bars as their hardware. Before 1878, this was not the case. Most doors were opened with a string, a bespoke handle made of wood, or even by sticking your finger into a knothole. 

Thanks to one Osbourn Dorsey, however, we now have a reliable and standard locking mechanism for securing our doors, one that hasn’t changed much, at least in principle, since the United States Patent and Trademark Office granted him a patent in 1878.

Since doorknobs, locks, and keys were quite expensive upon their debut in the world, it took a few generations for the technology to filter down from high society to common folk. Regular people would usually secure the doors to their homes and shops with a bit of leather wrapped around a protruding dowel or some similar setup. 

Thankfully, egress in commercial spaces today is much easier (and safer), thanks to crash bars and regular old door knobs.

If a Door Swings in, It’s for Good Reason

When you walk up to a commercial building, you’ll see signs on the doors instructing you to either push or pull to gain access. There is a good reason for a door that’s marked “PUSH,” and it has to do with security.

The reason revolves around hinge design and technology. Barrel hinges, typical in some commercial applications but also in residential doors, are usually mounted at the top, middle, and bottom of a door. The barrel where the hinge pin is installed is on the same side the door swings toward. 

If a commercial door with this style of hinge were to swing outward, the hinge pins would be exposed on the exterior of the building. All an intruder would need to be able to break in is a hammer and punch. They could drive the hinge pins out, lift the door from its mounting, and gain access in less than a minute.

The Revolving Door Is Almost as Old as the Doorknob

Theophilus Van Kannel was granted a patent for a triple paneled revolving door on August 7, 1888, which is about ten years after Dorsey got his patent for the door knob.

Probably one of the cleverest features of the revolving door — and the reason these doors adorn the street fronts of so many skyscrapers — is that it acts as an airlock. The atmospheric pressure in large buildings often differs from the ambient pressure outside because in summer, the building is cooler (denser air), and in the winter, it’s warmer. 

The advent of the revolving door didn’t just help solve pedestrian congestion; it also helped commercial air conditioners become more efficient.

We’re the Commercial Door Experts

At CDF Distributors, we stock and ship thousands of commercial doors, door packages, and hardware every day — direct to job sites or wherever you need them. Ordering is easy, customization is quick, and you can even get instant quotes online. Try our online tool, Pro Builder, for yourself today, and see how easy it is to work with the best commercial door supplier.

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