As-built drawings, or renderings of the building as constructed, are common in the industry. Many contracts require that the contractor or subcontractor providing the labor and materials to construct the project provide them as part of the close out documents. This is because there is often variation between the design, specifications, and final constructed product. Sometimes this change is known; while on other occasions it can be an unknown fact until it is measured.
Accounting for changes in scope by change orders for purposes of as-builts is easy to do. Smaller variations that come from work being slightly different than how it was designed because of small errors in measurements, for example, harder to detect. This makes it harder for follow-on trades who arrive on site to perform their work and are reliant on knowing that the site is really ready for them to start work. It can also make it harder for maintenance and repair contractors who come on site years later to perform work and don’t have accurate as-builts.
A new technology call 3-D imaging is helping the industry deal with these problems. Using lasers projected from a fixed point to multiple data points, the technology is able digitize an image of a building and 3 dimensions. Effectively, the building is scanned using millions of data points that are imported to draw a picture of the structure in much the same way we scan documents. Similar to surveying work it uses X, Y, and Z data points and assigns an intensity value to readings to “scan” the building accurately. With these images, owners, contractors, and others can get an accurate rendering of the building in the middle of or after construction is complete.
These technology is not widely used yet, but it has the potential to change the construction industry immensely. If integrated with Building Information Modeling, or BIM, the options could be endless.