Chiswick Park Building 7

Entered by TDS Midlands Ltd

Fully integrated BIM construction of offices

Building 7 is the last office block being built at Chiswick Business Park. Building 7 is a fully integrated BIM construction process, a first for many contractors including developer Stanhope, main contractor Lend Lease and steelwork supplier PAD Contracts. Following previous designs from building 6, building 7 has been constructed in a full BIM process. TDS undertook the drawing work of 3 external fire escape stairs, two with 24 flights and another with 22 flights, an internal stair consisting of 38 flights and 215m of balustrade to the roof perimeter. Due to the architectural detail of the stairs, challenges were aplenty. From the blind drilled, tapped and counterbored holes for socket head bolts, complex machined brackets to support tie wires, aluminum extruded and patterned flooring, patterned glass with kite marks, multiple phased construction, water profiled stringers requiring dwg profiles showing trace marks of all connecting items to one face as well as integrating the Tekla model into a 3rd party BIM application with full information covering fabricator, part mark, material, floor level etc etc all in a model with over 90,000 items.

Drastically reduced fabrication time

The most challenging items were being able to export a LOD400 compliant model out of Tekla into a 3rd party application. However, being able to create DWG drawings of stringers showing trace marks of connecting items to be waterprofiled was a huge benefit. There was a need to ensure identical plates had individual marks if connecting parts were located in different positions (eliminating the need to measure and setout items welded together - drastically reducing fabrication time and possibility of errors). The provision of thousands of blind holes, a large percentage tapped, as well as counter bored holes with tapped holes in connecting member and sometimes a clearance hole in final item was critical to the success of the project. Other benefits were gained from the modelling of extruded aluminum profiles and other machined items exported directly from the model which require fabricating on a 5 axis CNC machine.

A key benefit was the ability to collaborate by exporting and then integrating our models into a master project model which highlighted any potential clashes or design changes from the architects original concept at an early stage. Of course human intervention is sometimes needed in the clash detection process, for example where we had provided extra tolerance packing where the stair connected to the concrete floors, the BIM process picked up these as a clash although technically they aren't. It was critical that we were able to view the interfaces of the external stair fixing brackets which integrate with other trades to help resolve issues quicker and more effectively than a traditional 2D process of exchanging drawings. The export of 3D DWG files of the stringers to the water profilers complete with trace marks drastically reduced workshop time and eliminated the risk of parts being welded together incorrectly.