"Thoughts and Observations on Architecture and You"

21
The Value of a Property Survey

When undertaking a project that involves the construction of a new building, an addition, or a major renovation to an existing building, the information found on a property survey will be needed.

As the owner, it is your responsibility to provide a survey when one is requested by your architect or required by the building department. The architect, the building department, and the general contractor rely on the accuracy of the survey information to do their work. They do not wish to incur liability unnecessarily by incorrectly guessing property information.

Property surveys are done by licensed land surveyors and civil engineers. The cost to produce the survey varies depending on the type and amount of information requested. Sites that have challenging terrain or other physical obstacles that make the surveyor’s work difficult will cost more to survey. Relatively complete property surveys with topographic information for urban and suburban lots are commonly priced in the $3,500–$6,000 range.

After you, your architect, and your surveyor agree upon the types of information that are to be placed on the survey, a surveying crew will come to your property for a day or two to measure and record site data. This data then will be used in the surveyor’s office to produce a survey drawing.

Most surveyors have a “package” of information that they normally include on each of the various kinds of survey maps that they do. It is useful to get a written list of this information and have your architect review it with you. I have found that the surveyor’s list is often inadequate for my design work. To address this issue, I give clients my desired survey information and surveyor tasks to pass along to their surveyor. We then discuss why certain items have been requested, and whether any can be eliminated (for cost reasons) without causing future problems or delays.

It is important for a client to keep in mind that site information not gathered initially, but needed later, will require additional visits to the site by the surveyor’s crew. The cost of these subsequent site visits and modifications to the survey drawing will usually be greater than the additional cost of getting the information during the surveyor’s first site visit.

Common Survey & Topographical Map Information and Surveyor Tasks

Depending on the site and the building project needs, the following items should be considered for inclusion on the survey drawing:

• Location, length, and direction of the property boundaries: Almost all properties are subject to planning code setback areas within which only limited building is permitted. Setback lines are established relative to property lines.
  
  
• Location of any rights-of-way and easements: Construction is not normally allowed within these areas.
  
  
• Location of all lampposts, electric wire posts, fire hydrants, manhole covers, and catch basins (with rim and invert elevations): Your architect and contractor want to plan and build the project to take advantage of, or work around, these items. The building department will want to know their location when reviewing your project drawings. (For example, a nearby fire hydrant may be advantageous to you when certain fire safety questions arise about your building.)
  
  
• Location of visible portions of any underground sewer, water, gas, electrical, storm drainage, and communication lines, as well as tap points and meters within the property and off-site near the property lines: A surveyor will not plot the exact position of each underground line on the survey. He can locate the surface features of these lines to alert your contractor about their general location so that the lines will not be damaged during site and building demolition work. Tap point locations are useful to know where connections to these lines can be made.
  
  
• Location of all on-site driveways, curbs and curb cuts, walkways, decks, fences, retaining walls, and landscaped areas: Your architect may want to tie the new design work into existing pedestrian and vehicular pathways, or may wish to use existing landscape features or decks as focal points for some rooms. Site drainage will be influenced by pavement and retaining wall locations. Fences that were thought to be on property lines may not be.
  
  
• Location, size, and variety of trees within the property and off-site within five feet of the property lines, of a diameter of 6” or greater, with an approximate outline of the tree canopy: The exact location of trees is useful to your architect during design and is needed by your contractor when planning how to construct the project while protecting the trees. The variety of tree is helpful in determining the extent and depth of its root system.
  
  
• Elevations of the tops and bottoms of curbs, retaining walls, fences, and exterior steps; elevations of the tops of walkways and driveways, and of grade at building corners and at property line corners: Grade and pavement elevations (heights of different points relative to a reference point) are needed to determine site drainage directions. Allowable building heights are commonly referenced to the elevation of the top of the street curb at the center of the property width.
  
  
• Location of the “footprint” (the perimeter) of the buildings on the site, with length of the perimeter walls and distances of the corners from the nearest property lines; location of any upper floor and eave overhangs: The position of the building(s) relative to the property lines is critical in determining where additions and changes to existing construction can be made. The surveyor can get the most accurate location and length measurements with his instruments.
  
  
• Elevations of all building floors (taken at door openings), garage slabs, and decks: This information is needed to construct exterior wall elevation and building section drawings, and to accurately reference new construction heights to existing construction.
  
  
• Elevations of the tops of chimneys, all roof ridges, and roof edges at eave corners: Most planning codes limit building heights. It is necessary to know the height of different parts of the existing construction relative to those limits.
  
  
• Site contour lines at elevation intervals of 2’-0”: As a group, contour lines indicate site slopes and level areas, and reflect drainage patterns. For relatively flat lots of modest size, contour intervals of 1’-0” or 2’-0” are useful; for larger or steeply sloped sites, 5’-0” intervals may be acceptable.
  
  
• Location of building “footprints” and roof heights on adjacent properties: In urban areas, the allowable location and height of your building are often influenced by that of the buildings on adjacent properties. Your architect will need this information for the design of your building, and the building department may require it on the set of permit drawings.
  
  
• Establishment of all the corners of the property with permanent markers: It makes sense to have the surveyor mark the property corners with lasting markers for future reference.
  
  
• Establishment of a site bench mark for use during construction: The bench mark is a physical point of reference that is used to determine the proper height of all new construction work.

John McLean, Architect
San Francisco
(415) 777-9767