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Parcel Areas
Posted by sergeant-schultz on August 3, 2016 at 4:10 pmSo let’s say I’m surveying a nominally 1 acre lot 208.71′ square. My survey passes the ALTA test, just barely. To how many decimal places can I state the area before I’m dreaming?
paul-in-pa replied 8 years, 1 month ago 10 Members · 12 Replies -
12 Replies
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Sergeant Schultz, post: 384087, member: 315 wrote: So let’s say I’m surveying a nominally 1 acre lot 208.71′ square. My survey passes the ALTA test, just barely. To how many decimal places can I state the area before I’m dreaming?
A hundredth one way or the other will affect a 208.71′ square “acre” by two square feet. I prefer to give acreage to two decimal place, but have been forced to give three or sometimes four decimal places. If it was up to me, I would just state square footage (rounded to the nearest foot) and let others interpolate.
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43,600 sq. feet (208.806′ X 208.806′) = 1.0009183 ACRES has been found to keep all the fur stroked in the right direction
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I never give square footage. Not gonna start now. 0.001 acres amounts to 43.56 square feet. That’s close enough for the tracts I’m creating, especially since almost everywhere dictates a minimum of three acres for a new rural tract. If it’s a small tract out of a small city lot or something similar I do not list an area as no one really cares, IN MY PART OF THE WORLD. Your mileage may vary.
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Holy Cow, post: 384093, member: 50 wrote: 0.001 acres amounts to 43.56 square feet. That’s close enough …Your mileage may vary.
Apparently my mileage varies, Lot 826 below is 50 s.f.;)
In other “things are different all over” news I’ve been working on a survey for repairs/renovations to the National Air & Space Museum. They’re floating around a number for the final budget at one billion dollars – probably should have raised my fee
http://www.washingtoncitypaper.com/columns/concrete-details/article/20829491/why-air-and-space-should-build-anew -
James Fleming, post: 384108, member: 136 wrote: Apparently my mileage varies, Lot 826 below is 50 s.f.;)
In other “things are different all over” news I’ve been working on a survey for repairs/renovations to the National Air & Space Museum. They’re floating around a number for the final budget at one billion dollars – probably should have raised my fee
http://www.washingtoncitypaper.com/columns/concrete-details/article/20829491/why-air-and-space-should-build-anewI would think that 1% would cover your “usual” fee, wouldn’t it? Of course and ALTA would be a bit more.
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gonna go out on a limb and assume you have a non-surveyor asking to you add more digits.
couple of colloquialisms come to mind: “tail wagging the dog” and “don’t give ’em too much rope to hang you with”.
i try to practice the latter to the extent allowed because the first is getting way out of hand. attorneys, engineers, and clients asking why my 5.024 acre tract doesn’t agree with their 900 documents that say 5.028 acres like the deed calls.
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flyin solo, post: 384115, member: 8089 wrote: gonna go out on a limb and assume you have a non-surveyor asking to you add more digits.
couple of colloquialisms come to mind: “tail wagging the dog” and “don’t give ’em too much rope to hang you with”.
i try to practice the latter to the extent allowed because the first is getting way out of hand. attorneys, engineers, and clients asking why my 5.024 acre tract doesn’t agree with their 900 documents that say 5.028 acres like the deed calls.
That’s why I prefer to state square footage. A closed geometric figure’s area in square feet stays fairly “consistent” in appearance (to the non-surveyor) no matter whether you go the “HP” route or the “Texas Instruments” route or the “AutoCAD” route. To me it is more defensible than a unit where the thousandths place represents 43.56 sq. ft.
Sometimes acreage is like displaying fuel consumption in “Hogsheads per nanosecond“. I have sat through too many late night City Council meetings listening to idiots argue whether a 9.999999 acre tract meets the “10 acre rule” around here.
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So, if the sides of the square measure 208.71å±0.08′, then isn’t the uncertainty in the area going to be:
屉ö? [(208.71×0.08)^2 + (208.71×0.08)^ 2] = å±23.6 ft.^2
and if so, wouldn’t 3 decimal places be about as far as you can realistically go? Please correct me if I’m wrong.
I bring this up because I see maps all the time with areas carried to 5, 6 or even 7 places.
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208.71 x 208.71 = 43,559.8641 then divided by 43,560 = 0.9999968802
208.72 x 208.72 = 43,564.0384 then divided by 43,560 = 1.0000927089Anytime I see 5 or more decimals places, I think it must be their default CAD setting.
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Sergeant Schultz, post: 384129, member: 315 wrote: So, if the sides of the square measure 208.71å±0.08′, then isn’t the uncertainty in the area going to be:
屉ö? [(208.71×0.08)^2 + (208.71×0.08)^ 2] = å±23.6 ft.^2
and if so, wouldn’t 3 decimal places be about as far as you can realistically go? Please correct me if I’m wrong.
I bring this up because I see maps all the time with areas carried to 5, 6 or even 7 places.
Did you mean to add and subtract the .08′ (not multiply by .08′) which yields 66.8sf or .0015acre?? On a square 100 acre parcel the ALTA spec tolerance would amount to .0326 acres, so how you report decimal acreages depends on the parcel size.
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BajaOR, post: 384182, member: 9139 wrote: Did you mean to add and subtract the .08′ (not multiply by .08′) which yields 66.8sf or .0015acre??
I meant to multiply. What do you mean by “add and subtract”? I’m not getting it……
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Because of dealing with subdivisions I give to the nearest square foot (it is just math) and 4 decimal place acres. If a record deed is to 3 decimal places I seldom worry about any difference.
Paul in PA
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