The £3.5m design and build, one form entry school, being built for Kent County Council will be completed in September 2015. Since work on the project began, the construction team has been committed to collaborating on maximising the benefits of BIM.
All members of the project team, including contractor Baxall Construction, and architect HMY, began by meeting to agree BIM protocols to ensure they could collaborate effectively. A key part of this involved discussing the type of BIM software that would be used. Fortunately all parties were planning to use Auto Desk Revit, although the specific version of the software still needed to be agreed.
At stage 3 of the design process the construction team shared 3D software models, agreed standards and named software formats. It was agreed that BIM models designed by each member of the project team would be shared consistently, and at least every two weeks, to integrate the software and maximise the collective advantages of BIM.
Use was made of the Revit Family Library that lists component parts that are already drawn on BIM software. The library contains a range of fixtures and fittings such as lights, sockets, boilers, and doors that can be lifted straight into BIM’s 3D software models. If a component is not listed in the library it needs to be drawn manually, which takes time. Therefore, where possible, products in the library were used.
Significant benefits have undoubtedly been achieved by using BIM to design Holborough Lakes Primary School. Issues that Crofton could have faced relating to the M&E design have almost certainly been avoided. For example, for thermal reasons, 60% of the concrete slab needed to be exposed and other building services needed to be left uncovered and exposed on all classroom ceilings.
BIM enabled Crofton to accurately visualise and integrate the exposed services, and ensure they were designed to appear tidy. Had traditional 2D drawings that show each building service separately, been used, it would have been harder to neatly design the exposed services. The process would have been more time consuming, and issues probably would have arisen onsite.
Discussions with the contractor highlight the major benefits BIM brought to this project. A key benefit cited was certainty – completed BIM models enabled them to assess the exact quantity of materials to order and avoid wastage. For example, at the push of a button they instantly knew exactly how much pipework, fittings and plasterboard was required. With traditional 2D drawings human error makes under-or-over ordering almost inevitable.
The contractor has recently started developing its BIM capabilities, but says 3D modelling for the design and build of the school was so successful that it is now using BIM in a variety of ways. One relates to project management, where the software will be used at the start of projects to accurately estimate how long particular construction activities will take. For example, knowing that 1000 linear meters of pipework needs to be installed and where, makes it easier to accurately estimate the timescale of the installation process.
Going forward the contractor also says it plans to use BIM in the tendering process. It will work with organisations such as Crofton to ensure 3D models are completed early enough to predict an accurate price when costing jobs. It believes that being able to provide an accurate cost estimate for projects will be attractive to clients.
BIM also helped Crofton with structural and M&E service design by providing ‘clash detection’ that prevented problems. For example, amalgamated 3D BIM models ensured that all steel beams throughout the building could be identified, and that a route for building services could be designed around them. Again, traditional 2D drawings might not have identified steel beams, and caused problems onsite.
Because the construction team has engaged with BIM on this project, the software has brought about the working advantages it is supposed to do. It has enabled better overall design coordination, avoided anomalies, reduced onsite design issues, and has allowed Crofton to show the contractor and client exactly what will be built.
Crofton began investing in BIM in 2012. It is a major investment for any business as significant expenditure on computers, software and training is required. Time also needs to be spent setting up software templates, standardisation and knowledge sharing practices across a business if long term savings are to be achieved. Crofton’s strategy has been to gain BIM experience on smaller projects, before moving onto larger ones.