How to Calculate Grade, Fall, and Length for the Trades Person. Inches per foot, percent, and ratio

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I go over how to calculate grade given length and fall. Also the differences between inches per foot, percent grade, and slope as a ratio. I show how to do these problems on the whiteboard and also with a level and what the second line on the level is for. Help for trade exam, especially for the plumber's exam. How to calculate grade.
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[@denisewhite478]

Ty Ty Ty. You have saved me a lot of aggravation. Plus you didn’t make me feel like a total idiot😊

[@ColfaxMath]

Glad to hear it, good luck

[@genis8530]

Learned this in heavy equipment Operator school but haven't used it in awhile a good refresher I'm mostly doing slopes 3to1 4to1 grade.

[@ColfaxMath]

Good to hear

[@dominickquitoni8668]

Thank you. I have an existing water main in conflict with new stormwater drainage. Your lesson helped determine the exact elevation that conflict occurs and help facilitate an approved redesign with minimal owner expense.

[@ColfaxMath]

Great to hear the video was helpful

[@krismettrick6371]

I want to learn how to calculate grade for water drainage on a slope. Water is running downhill into our basement. I am excavating in front of our house to prevent water from draining under our house by reversing the slope in front of our house. thank you for helping me with the calculations. it made sense. Does anyone know the slop needed in compacted granite/dirt etc to drain water away from..

[@ColfaxMath]

Not sure how the water actually travels through different types of soil,

[@noahfigueroa3534]

You were born to teach! Great video. Thanks.

[@ColfaxMath]

Thank you

[@DottieA]

i,ve watched lots of videos on this subject and this is the only one i understand, THANK YOU1

[@ColfaxMath]

Great to hear, thank you

[@davidbarber5356]

You are great, explaining it so anyone can understand your math. Thank you so much.

[@ColfaxMath]

Great to hear, thank you

[@readplanet23]

Thank You sir for the educational video. I have been a fan of Trigonometry for many years. Keep up the good work. Have A Good Day!

[@ColfaxMath]

Thank you, have a great day

[@joshuawelborn7936]

About the clearest explanation!!

[@ColfaxMath]

Thank you

[@bentleynabigon-froese4484]

I was trying to understand this for my own math class, but I'm confused! The total length seems to be a horizontal distance (as in your diagram) but you later refer to total length as the length of the pipe! In fact the pipe will be longer than the "total length" from your diagram, because the pipe is your "hypotenuse". Is this a mistake or am I missing something? Thanks for the video though, it is very helpful!

[@ColfaxMath]

Yes that is correct

[@Skashoon]

Good stuff, thanks. I’m installing a tankless water heater and it requires a 3 degree slope for the exhaust pipe to prevent rain from flowing back into the combustion chamber. Now I’m befuddled. I used to know all this from geometry and trigonometry but that was in 1971-72. All I want to figure out (or be told) how much drop in inches do I need for a 16” length pipe?

[@ColfaxMath]

Thank you

[@thomassmearcheck2819]

you are a very good teacher !

[@ColfaxMath]

Thanks again

[@masterroberts5]

Hi there, do you have a video of this formula in millimeters? Chhers

[@ColfaxMath]

Not sure how it is done in metric except direct conversions

[@masterroberts5]

@@ColfaxMath no worries thanks, great video by the way.

[@osslv]

Thank you! You keep it simple.

[@ColfaxMath]

Thank you

[@diamondstateexcavationllc6478]

This was a great video! Just bought my first rotary laser and this helped a lot!! thanks!!

[@ColfaxMath]

Glad to hear it

[@-stealthy-cricket8209]

So, if you have a 6” pipe at an 1/8 “ slope what percentage is 1/8” ? There are no lengths available.

[@ColfaxMath]

If you do 6 divided by 1/8 you get a slope about 1 in 48 which is about 2 percent

[@thomassmearcheck2819]

you are a great teacher !

[@ColfaxMath]

Thank you

[@mateusrosa1]

Awesome explanation

[@ColfaxMath]

Thank you

[@aammiranda]

Basic math but great presentation; very helpful

[@ColfaxMath]

Glad it was helpful

[@kennydixson7851]

I knew all of that. What I really wanted to know was how much length you lose on account of the grade.?!?

[@ColfaxMath]

If I understand your question correctly, you lose the difference between the hypotenuse and the bottom leg

[@user-nv4ke8io4z]

Am not aware of the numbers,do we have constants?

[@ColfaxMath]

Just the measurements that you get off the site

[@user-nv4ke8io4z]

What's the formula?

[@irmaguzman4586]

Thank you

[@ColfaxMath]

Thanks for watching

[@t.n.1953]

You explained that a 1% slope is the same as 1/100 but how is it expressed as a ratio? Can you explain how ratios are used to express slope, for example a "3:1 slope." Is it for every unit of fall (3) there's a unit (1) of run? That seems extremely steep. Also, how does that translate to percentage?

[@ColfaxMath]

1 over 100 is a ratio. Rise of 1 and a run of 100

[@t.n.1953]

@@ColfaxMath Thank you for your reply. So is a 3:1 slope a rise or fall of 3 and a run of 1? I hear this used in instances where it would make for sense to be a 1:3 slope

[@TheBigdoggg33]

3 to 1 pitch is 3inches of drop for every foot of run. 1st number represents inches

[@teewithey5879]

What about if I only know the length and have to work out the fall by only knowing the degree at which it should fall at?

[@ColfaxMath]

If you have one length and angle have to use trigonometry to find the other pieces. There is a table you can use, or similar triangles

[@teewithey5879]

@@ColfaxMath could you elaborate on what to google because I’ve struggled finding anything like it. Could I convert degree to a percentage and work it out that way?

[@ColfaxMath]

@@teewithey5879 Tee, I'll try and get around to making a video on it.

[@samanthafranklin9159]

How many inches difference 24 feet2% the fall So what’s the cut to the toe?

[@ColfaxMath]

2% is 2 in a hundred or 1 in 50 or 1/2 in 25 approximately. If you 2% grade you would have to drop a half inch in 25 inches.

[@harryrantz6748]

I'm building a N scale Talmadge Bridge and coming off the Bridge it has a left hand curve then straight for about 2ft with a 2 inch fall. I'm trying to figure out what the grade should be, and what would the angle be in order for it to go from a 2 inch to a 0 degree with a curve at the top. Is that even possible? Can you help me out? Harry

[@ColfaxMath]

You can measure the height and calculate the run and get the average slope that way

[@genebush791]

Great video

[@ColfaxMath]

Thank you

[@stepheneurosailor1623]

Very helpful.

[@ColfaxMath]

Glad to hear it

[@reddye2331]

Bro takes the longest way home every day I guarantee u tht.

[@ColfaxMath]

Probably