News & PressThe City Surveys Group - The UK's Measurement Specialists
A guide to Measured Building Surveys
Published: 30th November 2016
This Article was Written by: Richard Furlong - City Surveys Group
Measured building surveys provide you with a full set of measurements of the key features of the inside of a building – its size, shape, interior layout, key features and so on.
A measured building survey is, keeping things simple, a way to visualise the interior of an existing building in two or three dimensions before work begins. They also offer an opportunity to record the existing form of the premises in virtual form so that any changes made during later redevelopment, alteration or extension works can be compared with the original.
Whilst varying significantly in the level of detail according to the client’s specification, almost all surveys of this type would pick up floor levels, door/window heights, opening sizes and so on. More detailed surveys (the need for which would depend on exactly why and by whom the survey is required) could also pick up finer details such as light switches, power sockets, coving, internal partitions and so on.
Such a plan or model could, hypothetically, be used for record keeping within a historic building, allowing future generations to see how the building has evolved over time. Alternatively, the floor plans produced by a measured building surveyor could also be used to give an architect employed to remodel the interior of a building an accurate, up-to-date picture of that structure’s layout. Without such a picture, an architect or developer will struggle (or find it impossible) to produce an accurate plan of any intended development works – without which a builder/engineer will be unable to work.
Detailed measured building surveys can provide different levels of accuracy and this allows them to be used as a general guide, e.g. for property sales and lettings or where, more precise measurements are needed, such as a complete internal redesign, the re-purposing of a building, the installation or alteration of services/utilities or extension work.
Measured data is typically delivered in a number of ways; the most common of which are traditional two-dimensional plans. Becoming increasingly common, however, are three-dimensional wire frames, often with realistic photographic textures overlaid onto them. A reputable, professional surveying firm will be able to tailor their deliverables to suit the client’s expectations.
As with all property surveys, the process is typically carried out early in any construction or refurbishment work – and often before any work has begun at all. It is important, therefore, that the survey be carried out with the necessary level of precision so that the data serves all the required purposes later on.
Whilst it might sound odd to the uninitiated, different types of survey demand different levels of precision. What’s more, not all clients/schemes require that every single detail be collected. Some clients simply need basic room dimensions whilst others will need every last detail picking up. It is very important, therefore, that the client fully explains their specification and their expectations before a quotation is obtained or any work is started. Any alterations to the specification or the intended deliverable after work has started or a quote has been provided may well lead to delays and an increase in costs due to revisits or increased office-based processing time.
Types of measured building survey
There are several main types of measured building surveys, including:
- Unconnected: Multiple separate surveys can be conducted across the site with no relation to one another;
- Semi-Connected: One storey is surveyed in full, with features along the vertical axis of the build positioned in relation to this ‘key floor’;
- Connected: The entire site or premises are surveyed in full, allowing features along any axis to be positioned precisely with respect to one another.
As an example, an Unconnected Survey might be used where the size of each room needs to be known but no structural work is being carried out that affects the division between them.
A Semi-Connected Survey focuses on the one most important floor – often the ground floor where there are likely to be more utilities coming in and out, as well as more entrances and exits and other facilities. While the other storeys are planned out in terms of common vertical features like walls, elevator shafts, wet and dry risers etc.
Finally, a Fully Connected Survey is the best choice if structural alterations are to be made or, more generally, where work spans a significant boundary such as multiple storeys or the outer wall of the structure. In this case, no one storey takes precedence but all – or at least, all that are to be worked on – are surveyed in equivalent detail to create a full three-dimensional plan with a consistent level of accuracy.
Implications of survey type
As you might imagine, the more connected the survey is, the more costly and time-consuming it can be as the different parts of the survey must be able to be mapped onto one another with the necessary degree of accuracy, as opposed to each individual survey being self-contained and separate.
Connected Surveys typically have the largest overall scale and scope, and it is sensible to choose a suitable scaling factor so that the compiled data, particularly for a very large site, contains the necessary precision but is also at a size that is manageable to work with either in whole or in part.
This might mean ignoring some smaller features if they are not significant to the work being carried out – or potentially conducting the Connected Survey at a scale of 1:100, with more detailed surveys of specific rooms at closer to 1:10 as appropriate.
Where higher levels of precision are going to be needed, this should be specified from the outset – don’t assume that a Connected Survey at very small scale will necessarily include more detailed larger-scale surveys unless they have been specifically asked for.
Conducting measured building surveys
Unless specifically requested by the client at the outset, the survey firm employed will typically decide on the best technology for the job choosing equipment that is rated for the desired level of precision and for any specific types of measurement that might be needed.
In practice, it is often the site itself that dictates how the survey will be carried out. This may begin with measuring the overall outline of the structure with subsequent measurements fitting within this overall template – particularly on Connected Surveys.
3D laser scanning using LiDAR technology can produce a three-dimensional point cloud, like a 3D dot-to-dot puzzle plotting the edges and apexes of each room’s significant features. This can then be stored digitally to be processed and manipulated as needed.
Combined with digital visual photography of each captured data point, this 3D point cloud can be given a graphical texture closely matching its real-world appearance, ultimately rendering the entire building interior in the form of a virtual reality 3D model that can be viewed and rotated at any angle.
We hope that this layperson’s guide has proved useful. We have deliberately kept the technical information within this guide to a minimum so as not to overload those relatively unfamiliar with this type of survey. If you would like additional information or would like to request a quotation, please contact The City Surveys Group via our contact page.
The City Surveys Group are one of the UK’s largest and most reputable surveying firms delivering a broad range of precision surveying, investigation and engineering services to some of the nation’s largest organisations. For more information on our company and how we can help you with your project, please visit our website.