Precision Pays: How We Shaved 16 Weeks Off a Construction Programme
Using LA’s architect-led measured surveys and BIM (Building Information Modelling) software, we enabled Lexi Construction to better their competitors’ programmes and secure the project. Here’s how!
Our Role
Working for the main contractor, LA were tasked with carrying out a 3D point cloud survey of a listed country house where a proposed garden room extension was to be built, and then with building an accurate BIM model, accurately incorporating the proposed extension.
The Objective
In order to ensure the highest level of accuracy, our BIM model itself could be used to place orders for the steelwork and glazing elements, without the need for verification dimensions being taken on site during the works.
The Consultation
Lexi Construction came to us with a question and a proposition: could we guarantee our survey and BIM model would be sufficiently accurate for them to place orders for key building elements without needing on-site, post-installation measurements? If we could, they would be able to cut the overall programme considerably.
This is practically unheard of in the construction industry, and not without good reason. In normal circumstances, steels would be ordered and the structure built before the resulting “as-built” measurements can be taken from which to confidently order the glazing. This process can take months.
However, we have complete confidence in our Architect-led measured surveys and their resulting BIM models, and we can therefore, reduce the risks for clients and help provide them with early cost certainty. In this case, we were able to provide the necessary reassurances to Lexi, allowing them to put forward a super-competitive programme, which was key to them winning the project.
“It was a pleasure to partner with LA London and LA Surveys on this unique project. Utilising their expertise in both 3D measured surveys and architectural BIM models, we were able to save 16 weeks on our procurement and construction programme because we were able to place advanced orders for building elements from the BIM model rather than waiting for site dimensions to be available. The accuracy of LA’s information and their proactive and efficient processes allowed us to deliver an optimum result to the client well ahead of any other contractor.”
The Survey
The 3D point cloud-measured building survey was carried out in half a day using our state-of-the-art Faro laser scanners. These allow us to scan a space with a high degree of granular precision, with a typical tolerance of just 5mm over a whopping 150m! This level of accuracy was vital for the unique requirements of this project.
Prior to the survey, we had identified the locations where the new steelwork would connect with the existing walls. So at these spots, we made sure that the survey was captured super-accurately and translated into a 3D model with the same precision. As architects, we make sure we understand the specific outcomes needed from every survey, including the requirements of those who will be using it.
As with all of our surveys, we also used the scanners to take measurable 360˚ panoramic photography of where the garden room would be built, meaning no return visits were needed; we captured all the data we would need in one quick visit.
From point cloud survey to existing and then proposed BIM model
The BIM Model
We used the raw data from the point cloud survey to create a detailed BIM model of the area where the extension would be built. This process itself requires a high degree of technical skill and precision as each point is traced into the BIM model using specialist software combined with a trained eye. As both surveyors and architects, we fully understood the context of the data we were interpreting for the contractor. This ensures we always have complete confidence in both our survey and our model.
Normal drafting conventions for creating a plan would see it drawn with the walls shown where they are at a height of 1.2m above ground, but this would have been too unreliable for us to coordinate structural steelwork that would be fixed much higher than this. While a wall may look straight to the human eye, in reality, there can be many minute variations which will impact the size of any new structure connecting to it. This is particularly the case in historic buildings, where we often find large variations in levels, including, for example, bulges and leans in walls. Our 3D scan accurately located the faces of the walls at all levels so we could build the BIM model to be completely correct at each and every point the steel structure would make contact with them whilst also allowing any bowing and projections to be accommodated. It was crucial that, where the new steels connected to the existing structure, the level of detail of these contact points was precise. We were able to provide an exact measurement at each spot, which the manufacturers could use with confidence to fabricate the steel structure and, subsequently, the glazing.
Structure and services coordination
The BIM model also ensured that clashes were easily avoided because our software highlights potential clash points in the model – for example, between a steel member and a downpipe.
The interactive panoramic photos allowed everyone involved in the project to access the proposed building site in a virtual environment, and to zoom in and out with complete accuracy, which is invaluable when the team are not all in the same place at the same time.
Structural setting out
The Outcome
The contractor was able to reduce their overall construction programme by 16 weeks by relying on the accuracy of our survey and the resulting BIM model from which to size and manufacture the steelwork and glazing before any structure had been built. This, ultimately, resulted in them winning the prestigious contract.
Do you need help shortening your project programme?