Design, science and innovation

Building a structure as tall as the CN Tower took a lot of patience, resources and, most of all, science! Check out the science behind key parts of the Tower, including our unique, curved shape and famous Glass Floor.

Glass

The CN Tower’s Glass Floor takes advantage of the strength of glass to create a thrilling experience, more than 340 metres (1,115 feet) up. And as much as it may be scary to stand—or sit—on it and look down, the floor can take it. But what is it that makes our glass so strong?

The glass used in our Glass Floor is made of silica, sodium oxide, lime and magnesia—it’s the same kind used for soda bottles, vases, mason jars and other household items. The molecular pattern of this kind of glass does not repeat in a symmetrical way—instead, it looks more like a spider web, but with missing strands. The bonds between silica molecules are very strong and the internal structure, although it looks hap-hazard, is a massive network of those strong bonds.

How strong? Well, the Glass Floor is strong enough to hold 35 moose—or more than three orcas!

Lightning

Have you ever wondered what happens when the CN Tower is struck by lightning?

A series of copper strips runs the entire length of the Tower. Copper is very conductive, allowing electrons from the lightning to move easily through it. These strips feed into massive grounding rods buried below the ground floor of the Tower. When lightning does strike the Tower, the electrical discharge runs through the wires and diffuses into the ground. 

And don’t worry, this system has been put to the test—on average, the CN Tower is struck by lightning 75 times per year!

Wind

When you’re this tall, you need protection from high winds. The CN Tower relies on an innovative shape and interior structure to protect against high winds—especially those coming off Lake Ontario.

The strength starts in the triangular base of the Tower. The three legs then gently taper and narrow as they reach the main pod, which reduces the surface area that wind can push on and lowers the Tower’s centre of gravity. To provide even more flex, hundreds of bundles of tightened steel cables run the full height of the Tower’s legs and core, helping to limit how much the structure can sway. And finally, two heavily weighted rings in the antenna help to counteract the sway, functioning like giant hula hoops.

On windy days, you can feel the building sway from The Top. But rest assured that the CN Tower is more than capable of weathering the storm!