How does a property surveyor actually decide where the property lines are?


I see this crop up in /r/legaladvice a lot where there’s a question of where one person’s property ends or begins, whether something is on someone’s property, etc. and the response is always that they should get a surveyor out to determine where the property lines are. But I don’t understand how that works?

I always figured that something like the title or whatever would already set that out and it’d be pretty clear to a layman precisely where their property begins or ends, but the amount of times there seems to be disputes about it makes it seem like it’s definitely not as simple as that, hence the surveyor.

So what does the surveyor actually do when asked to do this? How do they decide where the property lines are?

In: Engineering

I believe there are metal spikes in the corners of the lots. So a surveyor comes out with a metal detector to find them, and then you can draw a border of the lot because you now know where the corners are.

There are benchmarks which are marked locations from which the measurements are made. Now the measurements are taken using laser measuring devices. In the past they used a chain. A transit and surveying pole are used to measure the grade so that they can correct for the rise and fall of the land measuring straight line distance.

Before an area is marked like when we were originally settling America an accurate time peice and a sextant can be used to measure a location using celestial navigation. The first such place measured in the state of Mississippi was in Natches. Then that was used as the first benchmark for measuring the rest of the territory.

The land boundary corners can be a metal rod or stake in the ground yes. Or, it could be concrete.

But the real question here is how did it get there to that exact spot ? Usually they start with the land records as recorded in the town/city records and start at one known corner, then follow the survey description of the land boundaries around the property . This can get very complex and is a professional service.

Land Surveyor here. Typing from mobile.
In the U.S.A., and specifically Florida, we use plats for original surveys done, older surveys sometimes being 100+ years old, these surveys were good at the time, but not on par for today’s standards. Due to changes in zoning laws and sometimes sub-dividing property, you will find that there is sometimes multiple pins/rods/concrete monuments/wrenches/pine/spoons where a corner of property could be located. I say the older historical evidence is the property corner. For newer corners, surveyors now use a piece of rebar with a plastic cap. This is just for your local evidence.

To also determine your property for a single individual, surveyors will look at the block the house is on, hopefully a 4-way intersection (easier to use squares). This way surveyors and the city property appraiser/record keeper/city planner can see how a block was originally designed and measured. This also insures us that if multiple “pins” are in a line, that the pins are still reliable; this is if the houses are in a traditional rectangle block. To circumvent future problems, city engineers also ask to put all new peoperty coordinates in a “state-plane” system, meaning we have a coordinate where your property corner is at.

We find evidence with what you said a metal-detector, old sketches of the house, the math on the sketches (Bearing and distance), neighbors pins, house location, and similar things done on previous surveys and sometimes no found surveys. The problems that occur with this are line-of-sight, encroachments, and people aggravated you are on “their” property.