What is an As-Built survey? An as built survey records the measurements of a structure once it is built, this survey is conducted at several stages during a project. However, measurements can of course vary from the original design. It is crucial that any unintentional changes in the building process are noted prior to continuing constructing. Who needs an As-Built? There is rarely a time when an As-Built survey is of no service. As-Built surveys and drawings can be especially helpful if, assurance needs to be provided before a trade installs or works on a particular section. Or, if one simply wishes to ensure that the work has been done accurately and to the specifications.