Numbers on helipads atop of buildings in Los Angeles?

Question

What do all the different numbers on the helipads on top of buildings in Los Angeles mean?

Tall buildings have a 10 or a 12 medium buildings have from 5-8 . I have beel looking for info on this but I haven't found anything! I did try to look it up myself before asking. See example here to see what I mean, (It's a google maps link below)

http://tinyurl.com/338emd

Answer 1

The red numeral indicates the allowable weight, in thousands of pounds, that the facility is capable of supporting.

That explains big buildings having bigger number.

Check out the link below for more details.