Plat vs. survey

A plat is a recorded drawing - the official map of how land was divided, filed with the county, showing lots, blocks, rights of way, easements, and the bearings and distances that define them. A survey is the professional act of measuring land on the ground (and the resulting drawing), performed by a licensed surveyor and reflecting found monuments and field conditions at a point in time.

The plat is the record; the survey is the measurement. A new survey of a platted lot may disagree with the plat - monuments move, occupation drifts, old measurements carry error - and reconciling record geometry against field evidence is core surveying judgment.

When office work starts from the record, the first step is usually rebuilding the plat geometry in CAD so it can be compared, lot by lot, against new fieldwork or adjoining deeds.

Related: Convert a plat to CAD