What's a building survey: what are they used for

A Building survey is an on-site inspection of a property to identify any problems with the building to a prospective buyer. The inspection is carried out by expert surveyors who can then prepare a detailed report outlining any problems. Find out more!

A building Survey is a fundamental component for any construction project whose purpose is to properly define a property or land to successfully start the next design phase.

Among the most effective methods to carry out building surveys, drone surveying and laser scanning stand out. They result in a point cloud that allows the creation of 3D models and BIM models through specific software. These models provide a reliable basis for making decisions during the design phase.

If you need to create your 3D model from a point cloud, I recommend you try using a free point cloud to BIM software that greatly simplifies this process. To deepen your knowledge of construction and building survey, and understand the importance of this process, continue reading this article.

What is a building survey?

A building survey is the set of operations carried out partly on-site and partly in the office, by specialized technicians (usually surveyors). It aims at identifying the reference points necessary for the construction of new structures.

Whether it is a building, a bridge, a road or a pipeline, a properly executed survey allows not only to define the boundaries, the dimensions and the topographical characteristics of the intervention area, but also to establish the exact position that the structures will have to occupy on the ground. It is also a useful guide to the next construction phase.

To give you a better understanding of the importance that building surveys assume in civil engineering projects, in the following paragraphs you will find their main functions listed.

What are building surveys used for?

A building survey can take on different functions depending on when it is used during the design and construction cycle of a work.

Each civil engineering project usually begins with an accurate investigation of the area of intervention. In this first phase, the building survey represents the set of measurements and operations to be carried out with the aim to:

determine the planimetric and altimetric characteristics of that portion of territory subjet to the procedure;
identify the location of existing buildings and infrastructures, or any other natural or artificial element that could interfere with the construction of the work;
physically mark the points that identify the position on the ground of the designed structures, for example by staking and tracing the foundations (we will talk about it later in the article), and the pinning of markers and indicators of various kinds.

During the execution phase, the process of acquiring and returning the data which are typical of the building survey has the main purposes of:

checking the position of the structures during the construction phase;
verifying the correctness of the horizontal and vertical alignments;
assessing the accuracy of the construction components of the building;
implementing, if necessary, the necessary corrective measures.

Once the construction process is completed, the building survey becomes a survey of what has been built, commonly known as As-Built. As -built surveys are used to describe the work as it was actually carried out, and is essential to verify that the works have been completed according to the provisions and specifications provided by the project. When the whole design process is managed through BIM methodology, the current state of the work following its implementation can be documented through the so-called As-Built BIM model.

This model, developed using special BIM Authoring software, consists of a detailed digital reconstruction of the building that has the purpose of describing not only the location but also the characteristics of all structural, architectural and plant engineering elements.

As you may have noticed, building survey is an integral part of the design process of a work, but it plays a significant role especially in the initial stages because it guarantees the correct positioning of the structure within the intervention lot.

Not surprisingly, the term building survey is used very often to indicate the operations aimed at tracing the foundations. Let us then try to understand what exactly is meant by this expression.

Image of construction site team workers carrying out site building survey operations

Building Survey operations being carried out on-site

What is Foundation Tracking?

The tracing of the foundations, or “staking”, involves the transfer of a building project on the ground and consists of bringing markers and reference points to the ground. The aim is to provide the construction site workers with adequate indications on the positioning and correct execution of the foundation excavations and all the building elements, such as foundations, walls, pillars, etc.

The key points established during the tracking are essential to ensure the accuracy of the project and guide the entire construction phase. In particular, these indicators shall ensure that:

the construction is carried out within the legal boundaries of the area of intervention, avoiding future disputes;
the construction team carries out the work according to the planning and project provisions, reducing errors and costly reprocessing.

The choice of methods and tools to be used for the tracing of foundations varies according to the characteristics of the ground and the geometry of the building. Usually, the tracking operations are performed after the soil has been cleared of vegetation, debris and any other obstacles, and provide for the identification of alignments to first trace the external perimeter of the foundations and, subsequently, all other landmarks.

What are the tools used in the building survey?

The detection equipment includes a variety of instruments that industry professionals use to conduct measurement operations. The most common types are as follows:

Theodolite: it is a traditional, very precise instrument that allows to measure the angles both in the horizontal and vertical plane;
Total station: it is a more complete version of theodolite because in addition to the angles it allows to electronically measure also the distances and to store the data. It is mainly used for tracking;
GNSS (Global Navigation Satellite System): it is one of the most modern survey equipment, based on the reception of signals sent by satellite, and used to map the position of the points on the Earth’s surface;
3D Laser Scanner: essential for as-built surveys. This tool allows to detect the surface of the objects at very high speed and precision, producing a 3D point cloud. The latter is then imported into special software used to create 3D models;
Drone: it is a remote-controlled aircraft, equipped with a camera, used to detect large areas or to carry out investigations on the roofs or in particularly dangerous or inaccessible areas. Drones can also be equipped with LiDAR (Light Detection and Ranging) technologies for laser scanning.

If you are looking for a simple and fast, but at the same time reliable, way to model the actual state of a building in a BIM environment, my advice is to process the above-mentioned survey through a tool that allows you to obtain a point cloud and then rely on a Point Cloud to BIM software to transform it into the corresponding BIM model in a few simple steps. You will achieve excellent results, significantly reducing modeling times!