Frequently Asked Questions

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Here are the answers to some of the most frequently asked questions relating to our survey services. Please read through the questions below and follow the links to other related information.

Alberto Embarba of CADS

What is a measured survey?

A measured survey provides detailed, dimensionally accurate and scalable information on specific aspects of a site, structure, or building.

The survey data informs the work of architects, interior designers, space planners, structural engineers, civil engineers, mechanical and electrical engineers, building contractors, property professionals, and managers of estates and assets. And it’s accuracy is critical for the feasibility, planning, design, and construction process and to form the basis of reliable project costs.

Accurate information takes the guesswork out of the process.

What is a LIDAR survey?

A LIDAR (Light Detection and Ranging) survey – also known as a laser, laser scan or laser-sweep or point cloud survey use precise calibrated digital instruments such as laser scanners to accurately survey a site.

A laser scanner uses millions of individual laser measurements to build an accurate record of the areas and features to be surveyed, as demonstrated in this video.

This laser scan data is processed or ‘registered’ to create a 3D point cloud survey file from which 2D drawings or 3D models can be constructed.  The point cloud files can be both black and white or colour, depending on the project requirements.

They can also be issued in a number of different file formats (eg .rcs .rcp .E57) to be interoperable with your design software.

Measured building surveys are usually carried out using terrestrial laser scanners but may be supplemented with additional information obtained using traditional methods such as GPS, Total Station, Disto and photogrammetry.

While topographic surveys are usually undertaken using UAVs (drones) with supplementary information obtained using traditional methods such as GPS and Total Station.

What are the different types of measured surveys?

Trained surveyors verify and produce building and site information by undertaking surveys for various architectural, design and construction purposes. In summary these include:

  • Measured Building or Architectural Surveys – record the building fabric and architectural design of a building;
  • Land, Topographic and Utilities Surveys – record the site terrain, boundaries, levels and features as well as any hidden services using ground-penetrating radar;
  • As-Built Surveys – are surveys that record the building, fabric, architectural design and MEP (mechanical, electrical & plumbing) following completion of a construction or refurbishment project.
  • Verification Surveys – these ‘check’ surveys are used to confirm the accuracy of the project build against the proposed design or to confirm the accuracy of, and supplement existing information.
  • Area Surveys – surveys for accurately calculating areas of land or buildings for valuation; or for calculating property rental and rates, or for space-planning purposes.
  • Surveys for Construction – are used for engineering and setting-out services for sites and buildings for construction purposes including MEP installations.
  • Asset Surveys – record information for asset registers related to land and property regarding specific assets for activities such as planned maintenance.

The type of survey you will require will depend on the specific project and the information requirements you have.  You may require more than one type of survey for a project, for example, a measured building survey and a topographic survey.

“What Survey Do I Need?” insight discusses these issues in more detail.

What will my measured building survey cost?

A 2D measured building survey starts from £1200, increasing to several thousand pounds.

The price depends on the time that is required to collect the site data and convert it into 2D CAD drawings or 3D Revit models. The building type, complexity, condition and access can also affect the price.

It is therefore important that a detailed schedule of the project’s information requirements is prepared so that surveyors can ensure that they capture the correct level of data for inclusion in the final 2D or 3D deliverable. If the surveyor fully understands your requirements, they will be able to determine the most effective and time-efficient methodology to collect your data.

When procuring a survey it is generally beneficial to place a value on the quality, reliability and long-term use of the data you are purchasing rather than just on the price you will pay.

What information is required to carry out a survey?

The team requires a range of information about the building and project first to help us understand your survey need. This avoids time and money being spent collecting unnecessary data and preparing information that is not then used. The details we require include:

  • Location, details and an indication of size of the subject to be surveyed
  • Type and purpose for which the survey is required e.g. a land survey for a new building development project
  • Scope of survey required e.g. which areas are to be surveyed externally and internally
  • Specification of detail to be captured e.g. an outline of the structure or inclusion of fittings as well
  • When the survey is required by
  • Restrictions upon the survey e.g. timings for access or physical obstructions

With an understanding of the above, our Surveyor can ensure the correct scope, specification and delivery form of the project. For larger projects, we will make a site visit to fully inform the survey fee proposal.

What equipment is used for each survey type?

CADS operates the latest cutting-edge survey technology appropriate to the survey type being undertaken. Equipment used can range from traditional steel tapes and hand-held laser measures for simple 2D capture to the use of highly accurate laser scanners and Theodolite total stations for accurate and more complex surveys.

Measured building surveys are usually carried out using terrestrial laser scanners but may be supplemented with additional information obtained using traditional methods such as GPS, Total Station, Disto and photogrammetry.

Topographic surveys are usually undertaken using UAVs (drones) with supplementary information obtained using traditional methods such as GPS and Total Station

How will I receive my survey data?

Survey information is delivered electronically in digital file form, whether as 2D CAD drawings or complex 3D models.

Survey files can range from a few megabytes capable of being emailed, to larger and more complex surveys generating files of many Gigabytes which require other forms of delivery.

There are also different software programmes used across the property and construction world, it is therefore important to discuss with the surveyor both the type of file required and the most appropriate form of delivery when making the initial enquiry.

Security of the information in delivery and storage is also an important consideration for many clients and specific requirements can be agreed at the outset. Paper-based printed formats can also be provided for traditional 2D drawings.

What is a Scan to BIM or BIM-ready survey?

These two terms are interchangeable with the term laser scan survey which is used to capture the data on from which a 3D BIM model can be constructed. These measured surveys deliver an accurate based model that architects can use as the foundation for the design of a BIM project.

BIM (Building Information Modelling) is a broad term used to describe the process used for creating and managing digital information about a property or site and work collaboratively during the lifecycle of a project.

BIM standards

As with CAD standards, BIM standard align working practices to ensure continuity in projects and because BIM is a collaborative process it can have a big impact on productivity and ensure BIM implementation is effective, efficient, and sustainable.

PAS 1192-2 is a framework for project information management when using BIM. It defines the graphic ‘Level of Detail’, and data ‘Levels of model Information’ (LOI) in a 3D model.

ISO 19650 is the new international standard for managing information over the life cycle of a building or asset when using BIM. It contains all the same principles and high-level requirements as UK BIM Framework and is closely aligned with 1192 standard.

What is a BIM model?

A BIM model evolves throughout the lifecycle of a project as more detailed design and digital information is added. It can start as the deliverable from a laser scan or Scan to BIM survey and is normally prepared in Revit® software and issued in a .rvt file format, although exports can be made to other file formats where needed.

The elements represented in a 3D BIM model are usually specified using a LoD (Level of Detail or Level of Development) which ranges from 1 to 5.

  • LoD1 is a basic block form that lacks any real detail and is used for massing purposes, through to a
  • LoD5 which contains a high level of content and detail and is used for as-built record purposes and facilities management.

Generally, a measured building survey model is developed to a LoD 3 ‘architectural’ specification, but this can include some elements that normally only appear in a LoD 4 model.

What is Metadata in a BIM model?

Metadata are the properties that are used to describe and classify an object within a BIM model such as the manufacturer, performance, reference number, material, price, etc. BIM models can be rich sources of information with individual objects containing data about its geometry, descriptions, and other information.

How the Metadata are defined is important if the BIM model is going to be used to prepare schedules and reports for the construction process or post-construction use.

Our BIM survey model will only include this level of data if it is provided by a client and is normally only relevant on a full asset survey model at LoD 5.

What are EIRs and BEPs in a BIM project?

An EIR (Employers Information Requirements) sets out the information that the end user requires from the 3D model. Having an agreed EIR is therefore important when commissioning a survey for asset capture and facility management.

While a BEP (BIM Execution Plan) is the project plan developed in direct response to the client’s EIR and documents how the project will be organised and executed; and how and when the information will be created and by whom.

Because the 3D model is so fundamental to the success of the project delivery under BIM the BEP should consider the survey model, who will use it, how they intend to use it and what LoD and LoI is required to ensure that the survey model is fit for their purpose.

What is GIS (Geographical Information System)?

GIS or Geographical Information System is a software system that is used to create, manage, analyse and map all types of spatially related data. It works by layering and displaying location data in a digital map format.

The system allows you to organise and analyse locational information by mapping it on the world’s surface in its actual position relative to other features,

GIS connects elements and features within a map, to a database and by coordinating locations can help reveal patterns and relationships within a geographic context.

GIS is a great way to record and locate assets for management and planned maintenance purposes from grounds maintenance to plant.

Using a GIS improves productivity by providing faster access and analysis of information enabling more informed decision making. It also enables the sharing of key information and improves communication with an easily understood visual format.

 

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