Oakley Park, Hassocks

Client
- Pellings

Sector
- Residential

Instruments
- Autodesk AutoCAD
- N4ce software
- Trimble X9 robotic total station

Solutions
- 3D Laser scanning surveys
- Area referencing surveys
- As-built surveys
- Boundary surveys
- Construction verification surveys
- Measured building surveys
- Topographical land surveys
- UAV drone surveys

Challenge

Our client Pellings, a major design, property and construction consultancy commissioned Misura to measure 101 new build residential properties, as constructed by Taylor Wimpey and sold off-plan to Ropemaker Properties (a subsidiary of BP Pension Trustees Limited).

A highly complex project, the development consisting of a total of 500 new homes across private and social housing in Ockley Park in Hassocks, Sussex, was still pre-construction at the time of tender. Misura was asked to provide surveys for 12 different property types across 101 buildings. This was also a highly sensitive project representing both the builder and the buyers, requiring total transparency and impartiality.

Approach

To provide the most accurate data and drawing, we recommended to our client the necessity of conducting the measurements in two distinct stages. This approach would enable Taylor Wimpey to address any potential discrepancies and mitigate the risk of incurring penalties from Ropemaker Properties or jeopardising the contract.

For the first stage, we proposed measuring the footprint of each property at the oversite stage, when a layer of concrete is applied to seal the earth and establish the ground floor. This would provide an approximate assessment of the external dimensions and the gross external area of the plots at ground level.

In the second stage, we proposed measuring the properties internally, room by room, after the internal walls were constructed, to calculate the gross internal area.

The external and internal dimensions, along with the gross external and gross internal areas, would then be compared against the architects’ drawings.

We also suggested that the floor areas be maintained within 3% of the off-plan calculations, while the linear dimensions should not deviate more than 50mm from the intended measurements.

The first stage started with the establishment of ground control points and a traverse network in the phase 1 area of the site, using a Trimble X9 robotic total station.

Following the site inspection, the collected data was processed using N4ce software, a well-regarded proprietary software for survey computation and reduction, and subsequently plotted and constructed in Autodesk AutoCAD.

With the information obtained, we were able to determine the linear dimensions and the approximate gross external area of the oversites. A report was then submitted to all relevant parties, confirming that no discrepancies exceeding the agreed figures were identified.

The second stage was carried out approximately 6 months later after the properties had been built to internal partition wall stage, using a Leica RTC360 3D laser scanner. We selected black and white scans set to medium resolution, which allowed us to capture approximately 2million points per second, with a 1mm density. Although the scanner stores data using its built-in software, we opted to connect an iPad via Bluetooth to the scanner to gain access to a broader array of settings. This allowed us to assess the quality and completeness of the data capture, ensuring that no part of the survey was left unrecorded.

Outcome

A comprehensive report was prepared, summarising the survey findings. We identified discrepancies on some plots where the linear dimensions exceeding the established tolerance of 50mm. However, upon engaging with the various parties, we were able to demonstrate that the discrepancies did not affect the total floor area of the premises, leading to unanimous agreement among all parties to endorse our report.

The procedure of surveying in phases, preparing drawings, and calculating areas was systematically repeated for each of the six stages of the development.

Our meticulous approach, ensuring the highest level of accuracy and precision throughout the project, was a significant factor leading to the successful completion of the deal between Taylor Wimpey and Ropemaker Properties.