Architectural surveys: what are they for and how are they prepared?

Architectural surveys are specific processes that help architects, surveyors and engineers to understand more about the characteristics of a building. Find out more!

When intervening on existing building heritage projects, the first step to deal with is the architectural survey of the building to be recovered, restored or redeveloped.

This important process not only allows you to create an accurate graphic representation of the project, but also helps you evaluate qualitative and quantitative characteristics in order to make the most appropriate design choices for the following interventions.

If you’d like to find out more about this topic, continue reading the article and I’ll help you discover the importance of architectural surveys, most common techniques (from traditional to the most innovative integrated with Building Information Modeling) and the operating methods to correctly implement a survey process.

What is an architectural survey

The term “architectural survey” refers to rather complex investigations, carried out on site, and aimed at identifying the quality and characteristics of a building while returning graphical representations, in order to summarise the following data:

• state of conservation;
• crack and deformation;
• materials used;
• adopted construction systems;
• parts made at different times;
• transformations compared to the original.

This basically means that the scope of a survey must lead to an in-depth knowledge of the building under observation, and must highlight the most significant aspects not only from a geometric point of view, but also from a morphological, technological and structural point of view, with particular attention to the techniques and construction materials used, leading to decay and degradation studies and the relationships with the surrounding urban context.

Why surveys are important in architecture.

Thanks to their cognitive function, architectural surveys play a fundamental role in projects that involve intervening on buildings and represent the information basis necessary to support the subsequent design phases.

A survey that is prepared with care allows architects or heritage experts to graphically represent a building even without having adequate documentation or maybe for which you have only inaccurate or outdated information due to subsequent alterations or modifications over time.

With an accurate architectural survey and detailed knowledge basis, designers will be able to:

• rely on a solid starting point to develop the project idea: the survey is mainly used in the design of restoration interventions and constitutes a reliable basis from which to conceptualize the project and develop all subsequent operations;
• provide more accurate inputs: the relevant graphic documentation constitutes an indispensable dimensional support for all those preliminary searches that are carried out in relation to a correct design (such as structural surveys, mechanical damage, original geometric layout, structure verticality and horizontality, etc.);
• avoid errors and omissions: the architectural survey provides an exhaustive and detailed picture of the building and its dimensional characteristics, identifying and recording in the most appropriate way the particular construction situations and the specific characteristics of failure of the structures or degradation and erosion of materials.

What are the different types of architectural surveys

Depending on the tools and procedures used in the architectural survey, we can distinguish the following operational methodologies:

• Direct or longimetric surveys: carried out by the operator with the aid of simple measurement or alignment tools (such as the meter, the metric rods, the lead wire, the levels, etc.) and provides for measurement operations in direct contact with the product to be documented. The measurements taken are noted on a simple sheet of paper, which also shows an approximate sketch of the building, defined as an eidotype, which can then be transformed into a more accurate representation. In most cases, the direct survey is used as a basis to be integrated with the other procedures.
• Indirect or instrumental surveys: carried out with the help of topographical instruments (such as total stations, levels, spacers, etc.) and involves a series of more or less complex calculations in order to obtain a graphic translation of the objects detected within a system of spatial coordinates. Based on the visual collimation of points, the instrumental survey is used to make precision measurements, even in the case of very large areas or inaccessible points.
• Photogrammetric surveys: carried out with cameras and digital tools, called restitutors, which allow to extract the actual 3D model of the object from the individual photos.

In addition to these techniques, there is also the recent technological innovation carried out with 3D laser scanners. Laser scanners allow you to digitally acquire the shape and position of an object, describing it by means of Point Cloud clusters with spatial position identified according to a system of x, y and z coordinates, centered on the position of the scanner. Laser scanner surveys allow you to document the “de facto” situation of the built asset without having to worry about geometrical complexity or size, in a complete, fast and extremely precise workflow.

Survey with laser scanner

Of course, the choice of the most appropriate survey method  to be chosen varies depending on:

• the dimensional and qualitative characteristics of the object;
• the purposes for which the survey is carried out;
• site accessibility;

However, it should be considered that advanced digital techniques, such as photogrammetry and 3D laser scanners, allow the implementation of Scan to BIM workflows, a term that indicates a process aimed at creating the BIM model of an existing building directly from the Point Clouds obtained from a 3D digital survey and imported into special BIM software for digital modeling.

The Scan to BIM processes are used, for example, to intervene on buildings of historical interest, design recovery, redevelopment or renovation interventions, check the progress of works on construction sites, digitize existing works for facility management, etc.

Scan to BIM: from the point cloud to the BIM model

If you deal with BIM processes aimed at recovering existing building assets and want to experience the benefits of a Scan to BIM workflow, rely on a Point Cloud to BIM software fast and powerful, which helps you transform your point cloud (even large) in the corresponding BIM model with simple steps, by greatly reducing modeling times.

How to plan an architectural survey

To correctly carry out an architectural survey, it is necessary to carefully plan the actions to be carried out and elaborate a real survey project that describes in detail what to detect and how to detect it (specifying, for example, the choice of equipment, the reference points, the distances and the grip directions, etc.).

Through a first inspection (perlustrative) it will be possible to assess at a glance the shape and volume of the building, the internal distribution, the architectural and decorative characters, and the relationship with the context. Already at this stage it is advisable to produce a first photographic documentation and outline the eidotypes, or simplified sketches of the artifact to be used as a basis on which to take note of the visible details.

Parallel to the preliminary operations carried out on-site, it will be possible to develop research on historical and archival documentation, in order to find useful information on the genesis of the building and on the transformations that have affected it over the years. The results obtained from the historical survey can be cross-referenced with the information collected directly on the building during subsequent inspections.

Based on the acquired information, we can then move on to processing the survey, specifying the type of survey that we want to achieve in relation to the purpose and subsequent usage, the level of detail required, the type of information to be produced, etc.

After a second series of inspections, we’ll then be able to carry out the actual survey operations which, depending on the case, may consist of photographic acquisitions, direct measurements, laser scanner surveys, etc.

The last phase of the survey process involves the processing of the acquired data (such as, for example, the point cloud obtained from the laser scanner campaign) and the use of specific software and tools capable of returning the geometric model and the graphic representation of the scanned built asset.