How to Read a Survey vs a Site Plan
A survey records what exists and where the legal boundaries are; a site plan shows what is proposed. Both use similar symbols, so knowing the key labels makes either easy to read.
Reading a boundary survey
Property lines are labeled with bearings and distances, such as N 45°30'15" E 125.00', meaning the line runs 45 degrees 30 minutes 15 seconds east of north for 125 ft. Curved lines show radius, arc length and delta angle. Symbols at corners show monuments found or set (iron pins, pipes, concrete monuments).
Look for easements (utility, drainage, access) shown as dashed lines with labels, building setback lines, encroachments (fences, sheds or driveways crossing a line), the flood zone note, the surveyor's certification and seal, and the date of field work.
Reading a topographic survey
Contour lines connect points of equal elevation. Close spacing means steep ground; wide spacing means flat ground. Spot elevations give exact heights at specific points. The survey states the vertical datum (commonly NAVD 88) and benchmark used, which matters for flood elevations.
Topographic surveys also locate trees, utilities, structures, pavement edges and drainage features. Underground utilities may be marked from visible evidence and utility locate marks, so the survey notes will say how they were located and with what reliability.
Reading a site plan
Site plans are drawn over the survey and add proposed buildings, setback dimensions, driveways, utilities and drainage. On grading plans, existing contours are usually dashed and proposed contours solid; FFE marks the finished floor elevation, TW and BW mark top and bottom of wall, and INV marks a pipe invert.
Always check the legend, scale and north arrow first, then the general notes. If something is unclear, ask the surveyor or engineer who sealed the drawing.
Frequently asked questions
What does POB mean on a survey?
Point of Beginning, the starting point of the legal description that traces the boundary.
Is a mortgage inspection the same as a survey?
No. A mortgage location inspection or plot plan is less precise and should not be used to set fences or buildings.
What does NAVD 88 mean?
The North American Vertical Datum of 1988, the standard US elevation reference used for most new surveys and FEMA maps.
Sources
Have a project? Get a free quote.
Tell us what you need. An engineer licensed in your state replies with scope, fee and schedule.