Ayup. but you can get close enough to see if there's a problem with a
string level. Just drive a small stake in the ground outside the deck
and tie the string to it, pull it to the siding of the house, adjust
until the bubble says level and measure height at house and edge of
deck. the difference between the two measurements is your rise, I
assume you already know the run.


Or you can just pour water on it, and see if it runs off.
What's a patio supposed to be? 1:50?