Accurate information is needed about the location of all existing site elements and legal restrictions like easements in order to prepare the base map and base sheet. This information can be obtained from the following sources and then combined to produce the base map and base sheet:
• Legal documents
• Digital sources
• On-site measuring
The owners of the site should provide the designer with copies of two essential documents: (1) the property deed and (2) the plot plan. The deed is a written, legal document that transfers the title of property ownership from one party to another. This typically includes a description of the site’s size, dimensions, easements, and other legal restrictions. If the homeowner does not have a deed, the lending institution holding the mortgage on the house may have a copy in its files. Furthermore, a copy of the deed can sometimes be obtained from the city or county office that records property ownership and its transfer.
The deed is commonly supplemented by a plot plan or site survey (see previous discussion regarding the plot plan) and is considered a legal document when it has been stamped by a registered surveyor. Such a plot plan provides the most accurate dimensional information of all potential sources and is invaluable in making sure one is using correct information when preparing the base map and base sheet.
If no plot plan exists, needed site dimensions can sometimes be obtained from the city or county engineer’s office that has a copy of the entire subdivision or plat showing each individual lot within the subdivision. A record of a plot plan may also exist in the architect’s or building contractor’s office.
If none of these potential sources has a plot plan or other scaled information of the site, then the designer and clients need to carefully consider whether or not a survey is needed. Sometimes, the site and design proposal are simple enough not to warrant a survey. An experienced designer can often get the necessary site dimensions from both digital sources and on-site measuring (see later discussion). But if there is any doubt about where the property lines and corners are or if the site is difficult to measure, then a survey is highly recommended. Property lines are legal boundaries of the site, and so their location should not be estimated.
It should also be kept in mind that visual clues such as fences and hedges that seem to identify the location of property lines are sometimes wrong. Fences and hedges are often put in place by one of the homeowners on their own property, but not necessarily on or immediately adjacent to the property line. Where two adjacent properties meet in a grassy yard, lawn mowers may create an identifiable line often misconstrued as a property line. Additionally, the centerline of the space between the sides of the two houses cannot be assumed to be the property line because of different setbacks. Likewise, edges of driveways should not be assumed to be property lines. A designer should always be careful not to misinterpret what may seem to be an obvious property line. Exact location of property lines is essential.