Interesting facts about the Georgia Dome

Did you know the roof of the Georgia dome only weighs 68 pounds??

Here are some interesting engineering facts about the Georgia Dome.

Some more cool engineering drawings of how the dome roof works.

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Can someone check my math and assumptions on this?

The roof of the georgia dome weighs 68lbs (given)
The roof of the georgia dome is 395,000 ft^2 (given)
The roof of the georgia dome averages 1/16 in thick (guessed)

the roof of the georgia dome is 395,000/12/16 = 2057 ft^3
the density of the roof of the georgia dome is 68/2057 = 0.033 lb/ft^3 = .52 grams/cc

Now, from what I can find, the density of the lightest form of aerojel (which is the least dense substance known to man) is 1 gram/cc. Thus, the roof of the georgia dome is on the same order of magnitude of density as the least dense substance known to man.

Does that not make sense to anyone else?

Edit: nevermind, I found my mistake. aerogel is 1 milligram/cc. I should have remembered that water is 1 gram/cc. Remind me not to make these types of posts at 1am.