#1




Expressing Slopes or Gradients
I'm studying for Landscape Contractors License and have a question that I need to be sure I understand. According to the manuals a ratio of :
100:1 1' of rise per 100' of run or 1% Are these correct below 50:1 1' of rise per 50' of run or 2% 33:1 1' of rise per 33' of run or 3% 20:1 1' of rise per 20' of run or 5% 10:1 1' of rise per 10' of run or 10% 5:1 1' of rise per 5' of run or 20% 4:1 1' of rise per 4' of run or 25% 2:1 1' of rise per 2' of run or 50% 1:1 1'' of rise per 1'of run (this is the on throwing me) I thought 1:1 would be 1'of rise per 1' of run? Am I missing something or is there an error on the inch mark in the manual. Thanks 
#2




Your math is correct, however I believe you may have your ratios reversed. 1:50 rise:run ratio = 2% grade. Mathematically speaking, the : is equivalent to a division sign.
1:1 ratio = 100% 1:12 (inch per foot) = 8% 
#3




The manual list the ratios like I listed them (ie 50:1) The horizontal distance is always first with the vertical distance last.
The question I have is, in the book a 1:1 ratio 1 inch of vertical rise for every foot of distance isn't correct is it? Thats what the book states. In the case of 1:1 being 100% wouldn't it be 1 foot of distance and 1 foot of rise? Thanks for the reply. Hope i'm asking the question correctly. Thanks 
#4




If your book states it as a run to rise as opposed to a rise to run I would go with that then.....seems wrong to me but I have been wrong many times before. I know for sure that a inch every four feet (close to 50 inches) is the same as a 2% grade.
A 1 to 1 ratio signifies that all things are equal (ie: 1 foot per foot or 1 inch per inch or 1 anything per 1 same thing.) To express a 1 inch rise per one foot of run we need to work in a common unit. To express it as a run to rise ratio it would be stated 12:1. However it would be valid to state it as 1':1" so long as both units are shown. Clear like mud??? 
#5




In earthmoving I've always seen it expressed in run to risea 2:1 slope, a 4:1 slope, etc. If it helps to visualize it this way, a 1:1 slope is equal to a 45 degree angle. 2:1 would be 22 1/2 degrees.
We get plans for sewers with the slope expressed in percentages. 1% is 1 foot of fall in 100 feet of length. 2% would be 2 feet of fall in 100 feet. Pipe laying lasers are adjusted in percentage. Just dial in the specified percent of slope and follow the beam. Quote:
I think the 1" of rise per 1' of run must be a typo 
#6




Thanks for the replys. I think it is a typo error also. Just wanted to get another opinion to check.
Thanks 
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