Measuring the height of a structure may seem straightforward in the abstract, but sometimes in practice that is not the case. Take, for instance, a recent Southampton Town Zoning Board application – Matter of the Application of Hermann – where the height of a house was the subject of a challenge in front of the Zoning Board.

During construction of a residential dwelling, several stop work orders were issued and lifted based upon evidence submitted to the Building Inspector from different surveyors attempting to determine the height of the single family dwelling. Mostly the argument surrounded an interpretation of the term “average natural grade”, which is the point of measurement on the ground in Southampton. This case was complicated by two factors. First, the property was disturbed from the construction of a prior dwelling demolished to make way for the new dwelling. During the demolition the grade was lowered to accommodate a larger basement. Second, there was a ten foot change in slope from one side of the house to the other.


Southampton Town Zoning Code provides specific guidance for measuring the height of a structure in §330-5 “Definitions” which defines “Height of a Structure”. Section B of that definition states:

“In all other cases, the vertical distance measured from the average natural elevation of the existing natural grade (before any fill has been or is proposed to be placed thereon) as established on a plan prepared by a licensed professional surveyor, at and along the side of the building or structure fronting on the nearest street to the highest point of the highest roof or, in the case of a structure, to the highest point. On all flag lots and lots utilizing a right-of-way, the flagpole access or right-of-way shall be considered the street front.” (Emphasis added)

So, the challenge to the property owner was twofold:

  1. Determine a reasonable methodology to establish “average natural grade” on a previously disturbed lot; and
  2. Apply that methodology to a property that contained a significant slope.


Fortunately, the Zoning Board had decided two previous cases involving height variances that centered on determining average natural grade. In the Matter of the Application of Schwartz, the Board initially observed that determining the average natural grade of a parcel of property was an inexact science. Next, the Board determined that using spot elevation data and the Topographic Map of the Five Eastern Towns was a reasonable methodology in determining average natural grade. Finally, the Board determined that a single measurement or data point along a building line was insufficient and that at least two data points must be used to determine average natural grade which would then be the basis on which to measure height.

Approximately a year and a half later, the Zoning Board decided a similar application, the Matter of the Application of Rubin. In Rubin, the Board followed Schwartz by making these findings:

  • Measuring contours and topography is an inexact science.
  • Site specific topographical data is the most accurate piece of information necessary to determine average natural grade.
  • Interpolation of data derived from survey maps and site-specific topographical data is a reasonable way to determine grade issues.


Applying the findings in Schwartz and Rubin, site-specific elevation data combined with the most recent contour mapping available will allow a licensed surveyor to determine contour lines and use these contour lines to determine height.


The property owner in Hermann engaged a surveyor who used the following data to determine average natural grade:

  • 1956 Topographical Map prepared by the U.S. Coast Guard
  • 1973 Photographs of Original Foundation under Construction
  • 1974 Five Eastern Towns Topographical Map
  • Actual field data
  • 2007 LiDAR Contour Map
  • 2012 LiDAR Contour Map
  • Field Observation of Surrounding Topography of adjacent lot
  • 2015 Under Construction Photographs of the Current Foundation
  • Actual Height Measurement

Using that information, the surveyor made a determination that the house exceeded the permitted height, and the property owner had to obtain a variance. The request for relief was significantly less than that alleged by the neighbor, and the variance request was ultimately granted. In the Hermann decision, the Board found that the methodology used by the property owner’s surveyor to be the most meaningful and likely accurate because it incorporated the above data.


To determine the height of a building – at least in Southampton – a surveyor must consider all of the data available, especially when the property is already disturbed. It is also suggested that a property owner or surveyor provide the Building Inspector with the methodology used to determine average natural grade in advance of construction, so violations of height restriction are avoided.