# How to find elevations in feet ?



## Poolcontractor1 (Mar 3, 2017)

I'm new to the world of reading prints and I am having some trouble understanding elevations. All the prints I have been working with have base elevations of 100. Which is usually the top of concrete on the deck of the pool. Let's say the excavation drawing says the deep end is at 94.7 how do I figure out what that is in feet.? Any feed back/help is greatly appreciated. Thanks


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## sunkist (Apr 27, 2012)

pass


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## rondon (Feb 10, 2010)

that is telling me it is 5 ft 8 3/8 inches below benchmark.

the .7/12 equals 8.4 inches

the .4/16 equals 3/8 inch


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## CENTERLINE MV (Jan 9, 2011)

To figure it out quick & easy in the field, you can use a construction calculator (or app for your smartphone). Type in "94.7 feet" then "convert"' then "feet" it will display the fraction 94' 8-3/8"


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## bwiab (Mar 17, 2006)

Your elevations are in feet. They are in decimal feet which measure feet to the 10th. You need to convert to feet and inches. Other posts above show that.


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## Fouthgeneration (Jan 7, 2014)

Its time to learn how a number line works or you are guaranteed to make some very large errors that cost thousands of dollars.

I'd buy an Engineer's rule or surveying rod laid out in decimal feet, and then fasten a inch foot rod or tape to it tightly...... converting from inches to decimal feet never ends well till you are an expert, and even then stress can cause errors.

When crossing zero, add another rule counting up if needed, and a fourth rule can used be to check sums that cross the Zero elevation

I work with masons every day that get confused about the zero point of elevation, one reason most prints use 100 as FFL instead of zero,

The zero is a johnny come lately to math, even Jesus Christ was born before the early R. Catholic bishops understood it, so JC ended up born in 1 A.D instead of Zero,which was skipped going back to 1 B.C A thoroughly fooed up mess.

Yes, that is why Prince's "Party like its 1999!" had the end of the Millennium a year early.....2017 is the SIXTEENTH year of the 3rd millennium. As an nearly useless factoid.


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## greg24k (May 19, 2007)

Poolcontractor1 said:


> I'm new to the world of reading prints and I am having some trouble understanding elevations. All the prints I have been working with have base elevations of 100. Which is usually the top of concrete on the deck of the pool. Let's say the excavation drawing says the deep end is at 94.7 how do I figure out what that is in feet.? Any feed back/help is greatly appreciated. Thanks


You better get this down good, because all engineering drawings and surveys are in decimals. 

Good luck


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## tgeb (Feb 9, 2006)

What you will find is that you are dealing with hundredths of a foot. It takes some getting used to, but it is the way surveyors have worked for centuries....ask George Washington. 

It's not too bad when you have site specific elevations, such as you stated that pool deck is 100', it gets trickier when you work to sea level and have to go locate benchmarks.

I was pretty familiar with the system in my teens, but took a course on surveying in my 20's to build a better foundation as to the processes.

It's simply another way of measuring....kinda like the metric system but much easier, cause it's still feet.


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## JDEERE (Feb 3, 2015)

rondon said:


> that is telling me it is 5 ft 8 3/8 inches below benchmark.
> 
> the .7/12 equals 8.4 inches
> 
> the .4/16 equals 3/8 inch


The above is not correct.

This is actually pretty simple once you get used to it. When you do, you'll hate working with fractions of inches. First, just take 100.00 and subtract 94.7, which equals 5.3 feet. 5 feet is 5 feet in both system so all you have to do to get inches is convert the .3 feet. To do that just multiply .3ft X 12in./foot and you get 3.6 inches. So, your distance down is 5'-3.6" or 5 feet and slightly more that 3-1/2".


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## Moxley-Kidwell (Jan 28, 2011)

Get a folding rule with engineers scale and feet/inches. The difference is 5.3 feet, find 5 feet 3 10ths on the engineers side, hold your thumb on the side of the rule on that mark, turn it over to the feet/inch side and read it. No electronics or other aids needed.


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## CharlieDelta (Aug 17, 2016)

JDEERE said:


> The above is not correct.
> 
> This is actually pretty simple once you get used to it. When you do, you'll hate working with fractions of inches. First, just take 100.00 and subtract 94.7, which equals 5.3 feet. 5 feet is 5 feet in both system so all you have to do to get inches is convert the .3 feet. To do that just multiply .3ft X 12in./foot and you get 3.6 inches. So, your distance down is 5'-3.6" or 5 feet and slightly more that 3-1/2".


This is probably the most straight forward way I have seen it explained in this thread. You're converting a decimal foot to inches. Pretty simple math, don't over-complicate it.

Edit: Also, when you have the 3.6" you can use the following to get it within a 1/16th of an inch.

*Ex.* Convert 7.90" to the nearest 1/16". 

Take the decimal, in this case 0.90 and multiply by 16 to get 14.40. Now round that number up or down. In this case we round down to 14. So now we put that as the numerator and get 14/16= 7/8. 

Thus, 7.90" is nearly equivalent to 7.875".


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## ChristineNova (Apr 29, 2017)

CharlieDelta said:


> This is probably the most straight forward way I have seen it explained in this thread. You're converting a decimal foot to inches. Pretty simple math, don't over-complicate it.
> 
> Edit: Also, when you have the 3.6" you can use the following to get it within a 1/16th of an inch.
> 
> ...


 
Totally agree. I teach blueprint reading to Plumber, Steamfitter & Welder Apprentices and I've found that this is the easiest way to do it "by hand". 

Can't go wrong with a trade calculator, but getting apprentices to understand WHY is as important as HOW.


100-94.7=5.3FT

0.3FT = 0.3X12inches (in each foot) = 3.6"
(think: 0.25 of a foot would be 3", right?)

3.6IN = 0.6X16(ths of an inch) = 9.6 sixteenths (round up to 10/16 or 5/8)
(think: 0.75 of an inch would be 3/4 or 6/8 or 12/16, right?) 


therefore:

5 FEET + 3 INCHES + 5/8

5'-3-5/8"


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## ChristineNova (Apr 29, 2017)

I'd also like to add that when you use the metric system this become exponentially easier.

If the deck was 100m elevation and the bottom of the pool was 94.7m you'd know right away the pool was 5.3m deep or 530cm or 5300mm


Is my Canadian showing?


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## Fouthgeneration (Jan 7, 2014)

ChirstineNova @ posts 11 & 13: survey in USA doesn't use decimal INCHES, rather feet, so converting same is off post......


If the metric system was the be all and end all, its users would rule the World......:thumbup:

FYI the 'english' system is and has been defined by metric units for hundred + years........:jester: An inch has been exactly 2.54 centimeters for well over a hundred years.....

A few minutes a day doing some conversions will yield an expert in a few weeks, till then get a second set of brains on the high dollars grade points.:whistling

FYI 2: the swimming pool is NEVER filled to the walk deck, just to the wave suppression gutter.....thus a 2 meter deep pool bottom is more then 2 meters away from the walk deck elevation.....

One pointer : always use the two significant figures to right of the decimal place on decimal feet measurements to reduce confusion...

Never mix decimal inches with decimal feet unless absolutely necessary
Whenever possible set the Hub stake at Zero or the First floor level to reduce offset errors....:blink:

Never assume the floor is actually at or near its designed height everywhere, mark out clearly "bench marks" that are at the designed FFL for use in checking other elevations, don't allow dimensional errors to stack up when avoidable...


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## Fouthgeneration (Jan 7, 2014)

Never say Never, there are "edgeless pools"......


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