What the certificate shows
A licensed surveyor, engineer or architect normally documents key elevations, the building location and diagram, the map panel and the applicable flood zone. It does not itself change the map.
When you may need one
Your community may require an elevation certificate for construction compliance. It can support a map-change request. Under Risk Rating 2.0, an elevation certificate is generally not required to obtain an NFIP quote, although providing one can sometimes help your rating.
How to find an existing certificate
Ask your local floodplain administrator, seller, builder or insurer first. If no valid certificate exists, ask a qualified local professional about the current FEMA form and the work needed.