GEOTECHNICAL I TOPOGRAPHY / SURVEY - WHAT IS THIS STUFF?

These are technical terms for soils engineering and land mapping. The need for these consultants on your will depend on several factors. Whether your project is new or an addition, these include the location of the project relative to the property lines, the slope of the lot and general knowledge of the existing soils in your area. Also if an addition, to determine the allowable size and location of your project relative to the existing house.
 

SOILS ENGINEER (GEOTECHNICAL)

Simply put: Soils engineering is the process of determining the strength of the soil on your lot as well as its stability relative to earth movement and moisture content. This is determined by knowing what soils are like in adjacent areas and the soil stratifications in your area. This knowledge is gained from years of work and acquisition of known data from reliable sources. The other key element and most important element in soils engineering is a boring. This is a hole that is drilled on your property to physically take samples of the soils that make up your lot. Typically these holes vary from 15 feet to 50 feet in length and tell the engineer relatively accurately the type of bearing capacities that can be used for your structure. The soils engineer produces a report and specific foundation design load figures that are used in turn by the structural engineer to design the foundation for loading, earthquake resistance and moisture content of the soil.
 

SURVEY

A survey is a map on your lot legally describing the property lines in direction and length. Surveys are tied back to datum points (known reference points documented with the County). A survey performed by a licensed engineer complies with the records at the County or City Hall as well as the legal description that you received from your title company when you purchased your house.
 

TOPOGRAPHIC SURVEY

A survey in and of itself assumes that the lot is as flat as a pancake and makes no reference to slopes or . When this information is provided then the survey becomes a Topographical Survey. This document not only defines the property lines as mentioned above but also shows the slope on the lot. stating the lot's high point and low point. The slopes are depicted by contour lines at a defined distance apart. The lines are together the steeper the land and conversely, the farther the lines are apart the flatter the land. Typically, contour lines are 2, 5, or 10 feet apart. The output of a survey with or without information is a drawing of the lot to scale. The document, either a survey or a topographical survey is then used by the architect to locate a new house or define to what extent an addition is acceptable in relation to the property lines.
 

COST AND NEED

Both of these items are commissioned at the outset of a project. But do not acquire them until you are asked to them or your architect determines that they are needed. They can be expensive to produce. Typically, in the range of $1,500 to $4,000 depending on the size of the job and the degree of difficulty in amassing the information needed to generate the drawing or report. These services are usually paid for by the homeowner and are not part of a fee relationship with your architect. Your architect should be able to assist determining the need for either of these and make a recommendation on what firm would be correct to use the extent of the effort performed by the engineer. Therefore, wait until you have a sense of your project until you have talked with your architect prior to securing this information.