Remember this: Just because we can does not mean we must.
I doubt anyone here does measure 10 acres with equipment and practices to permit accuracy statements down to the 0.001 of an acre as a normal course of business.
@dmyhill I’m curious if you computed the acreage based on the boundary B&D and then topo the whole parcel and created a surface would the acreage of the surface match the acreage in the plat? Take a stockpile for instance, if you locate the perimeter and calculate the area, then you topo said stockpile won’t it have a different area?
I was always told that in real estate the vertical acres are free.
Here in NYC we typically show lot areas to the nearest 0.1 of a square foot, if we were to round to the nearest square foot we'd be getting calls from the designers looking for a more precise number. Considering the average price per square foot in Manhattan is about $1600 and you might be able to build a 50 story tower on a property, that single square foot of land could be worth $80,000 or more.
@on_point Acreage and surface area are not the same. The steeper the slope the greater the difference.
That would make Colorado larger than Texas.
I only survey flat pieces of land...I mean the paper lies flat on my desk, so...
No, I have never ever bothered to compute the area of a surface, I suppose it is an output in the software somewhere, but I have not looked.
Here in NYC we typically show lot areas to the nearest 0.1 of a square foot, if we were to round to the nearest square foot we'd be getting calls from the designers looking for a more precise number. Considering the average price per square foot in Manhattan is about $1600 and you might be able to build a 50 story tower on a property, that single square foot of land could be worth $80,000 or more.
What is your confidence in that measurement? 66% 95%?
Here in NYC we typically show lot areas to the nearest 0.1 of a square foot, if we were to round to the nearest square foot we'd be getting calls from the designers looking for a more precise number.
Why would the designers care what the parcel is labelled? No matter how many significant figures are used, the lot area remains the same in a CAD drawing and they won't know any different.
Basic error propagation:
Let's make it easy and say we have a tiny rectangular lot, 100 foot by 100 foot.
Let's also say we are super confident in our measurements - down to the nearest hundredth of a foot.
(A ±X) * (B ±Y) = AB ±(AY+BX+XY)
(100 ±0.01) * (100 ±0.01) = 10000 ±(100*0.01 + 100*0.01 + 0.01*0.01)
or
10,000 ± 2.0001 square feet
Start throwing irregular lots in there, with 3, 5, or dozens of angle points, and allowing for typical positional tolerance of survey lines and monuments (anyone here certifying to sub-centimeter precisions?)....
That being said, I've caved in to regulatory and planning boards in the past on such ridiculous matters, and will probably do so again.
@drakej6, If the real estate clients are demanding area reporting to the nearest 0.1 s.f., then they apparently have no idea that they are demanding something that no land surveyor can possibly deliver.
If you are surveying a 1 acre lot, you need to be employing equipment and methods which allow you to reliably reproduce measurements resulting in less than 5/10,000 of a foot in the positions of all corners. There is probably industrial machinery placement equipment than may be able to accomplish that, but there is no land survey equipment that can come anywhere close to that.
Not meaning to get personal with this, but if you are certifying to results that precise, you are perpetuating a belief in an impossible standard and, by definition, committing a fraud.
I'm glad I don't work in an area where I would feel pressured to go along with that kind of reporting.
How does it work out when a resurvey disagrees with a previous survey by a few square feet?
