How modelling can overcome a constrained budget and tight timeframe on school expansions.
Like many across the country, Mayfield School in Redbridge, north-east London, had been identified as requiring significant expansion to deal with a high demand for places.
“The project had a tight 17-month programme and a relatively constrained budget of £18.2m”
The local authority had determined that the size of the school needed to increase from eight to 12-form entry, with new teaching and learning space for 800 students and 80 staff, alongside new sports facilities and dance studios to be shared with the local community. The project had a tight 17-month programme and a relatively constrained budget of £18.2m with which to create new spaces to achieve the ‘culture of aspiration’ required by the brief.
Ramboll UK was appointed to provide a full range of engineering services for the project. Working with David Miller Architects, it was identified at the outset that for it to be a success, a truly collaborative approach between the design team, contractor, supply chain and client was required.
Modern method for live site
The team realised that using a modern method of construction was crucial to achieving a programme that would maintain a high-quality finish and a clean and safe environment in the middle of what was to remain an active school site.
For these reasons, the project team selected cross-laminated timber (CLT) and glulam column and beam construction as the primary materials to form the structural frame. This was teamed up with a fully integrated building information modelling approach.
Through the adoption of a collaborative model approach, the design team was able to collapse the usually linear project programme.
BIM areas of success
- Integrated supply chain: models from the specialist CLT frame supplier and the MEP supplier were integrated into the design team model post-contract. The BIM data was then used to drive the CNC cutting machines in the CLT production plant in Austria. This ensured that when the CLT panels were cut, all structural and services openings were ‘right first time’.
- 3D model navigations and visualisations: enabled proposals to be clearly communicated to all parties, encouraging confident and timely decision-making while managing stakeholder expectations and buy-in. The model was also used to understand phasing, which improved site planning and safety – particularly important when working within a live school site.
- Cost management: the quality of the co-ordinated information allowed detailed and early cost analysis by the contractor, which led to cost certainty for the client. Accurate quantity schedules from the model for key packages enabled suppliers to provide well-informed cost proposals prior to financial close.
- Point cloud surveys: using the data from scans of existing assets speeded up the design of interfaces between old and new buildings and at the same time improved accuracy.
- BREEAM: the environmental performance was developed within the BIM model by embedding information. This ensured the design progressed methodically to achieve the Excellent target.
With two teams working in the model in parallel, one developed the full planning application within a seven-week period, while the other developed early construction information.
This enabled the timber frame, and other major subcontracts like the cladding, to be procured as soon as financial close was achieved.
Critical path management
The use of offsite manufacturing allowed the structural frame to be taken off the critical path, reducing time on site.
The CLT superstructure was completed in just 12 weeks and fit-out started on the lower floors even as the upper floor frame was being erected.
Ramboll Mayfield School BIM render 2
Where possible, the timber was left exposed and expressed as part of the design concept, bringing a lightness and warmth to the interiors that also offers the advantage of reducing the time required in the project programme for wet trades.
From experience in working on timber structures, Ramboll led early engagement with specialist subcontractors. This allowed for the development of a set of rules which were applied to the design to maximise the efficiency of the CLT panels by optimising spans and widths.
Using an integrated design and construction process centred around BIM, Mayfield School demonstrates that high-quality bespoke school solutions can be procured and delivered within reduced budgets and the constrained timeframes demanded by the need for new school places.
Jonathan Bawcombe is a design engineer at Ramboll