Cadastral and Subdivision Practice
Cadastral questions test how DC land is divided, platted, and recorded, and how zoning constrains the result. You need to know the difference between a record lot and a GIS polygon, and how a plat becomes the controlling document.
Platting and record lots
- A subdivision plat must be prepared by a DC-licensed land surveyor, checked for closure and area, approved by the Office of the Surveyor, and recorded with the Recorder of Deeds. The resulting lots are record lots.
- Resubdivision replaces existing lot lines; the new plat must show adjoining record lots, squares, reservations, and all encumbrances such as easements.
- Street and alley closings require the statutory closing process, typically an act of the Council, with a survey and plat; the closed land is then disposed of or attached by record.
- Condominium regimes are created under the DC Condominium Act; the condominium plat and declaration define units, common elements, and limited common elements.
Zoning and site constraints
- 11 DCMR governs lot area, lot width, yards, height, lot occupancy, and the Green Area Ratio. A lot must satisfy every applicable dimension, not just minimum area.
- Historic districts, PUDs, and campus plans may impose additional review.
Worked example
A 12,000-sf lot in an R-2 zone is proposed to be split into Lot A of 5,600 sf and Lot B of 6,400 sf. The zone requires 5,000 sf minimum lot area and 40 ft minimum lot width. Lot A meets the area test but measures only 38.0 ft along the front lot line. The subdivision fails the width requirement; the plat needs revision or relief before recordation. Area computed by the coordinate method does not cure a dimensional deficiency.
Traps that cost marks
- Treating a GIS parcel polygon as a record lot.
- Checking area but not width, yards, or GAR.
- Forgetting to show easements, reservations, or closed alleys.
- Recording a plat without the Surveyor's approval or the surveyor's seal.
- Ignoring that a recorded plat, not a deed sketch, controls the new lot lines.