CRANLEIGH SCHOOL VAN HASSELT CENTRE

CRANLEIGH SCHOOL VAN HASSELT CENTRE

Modular  floor and roof elemets with great connection details

“Cranleigh School Van Hasselt Center”

Client: Cranleigh School

Contract: £7.2 million

Project manager: Synergy LLP

Architect: Allies and Morrison Andrew Nevin, Jack Stephenson

Engineer: Ryan Associates Consulting Engineers  Gerard Doyle

Service Engineer Method Consulting LLP

Timber design: Metsä Wood UK - Ewa Ostrowska, Ryan Shaw

Main contractor: Durtnell-  Richard Bleach, Alan Maile

Steel Fabricator Austin Divall Fabrications Ltd

Panels manufacturer: Dupac

Panels installation :Mint Construction Gerard Lockey

Area: 2,525 sqm

Location Cranleigh, Surrey GU6

Introduction:

Located within the established historic campus of this independent boarding school, the proposal redevelops and expands four disused squash courts. Using this building as a central core, the design innovatively wraps modular, flexible teaching accommodation over two floors around its masonry elevations. Within the existing building, the generous proportions of the squash courts are exploited to create unique student social spaces, connected to the school’s history.

The van Hasselt Centre provides a new academic block with 20 new classrooms and department offices .

The new structure consists of a steel frame superstructure with Ripa  Metsa Wood Kerto Stress skin  panels creating  floor and roof.

 These panels have been designed to span 6.8m with a 100mm concrete topping for acoustic purposes throughout. The timber floor / roof is  left open to the underside as the finished soffit.  The Kerto floor elements were design to withstand 30minutes of the fire with additional 30 achieved with application of fire retardant. The Project was coordinated using BIM,  ifc and Revit files. The coordination between architect, engineer, steel manufacture , panels manufacturer and site was hugely improved and minimised mistakes and problems on site. Kerto-Ripa® is an enhanced design system for roof- and floor elements, developed by Metsä Wood. Based on Kerto® LVL  S-beam & Kerto® LVL Q-panel loadbearing components and  structural gluing it enables the elements very long spans, up to 20 meters, making it possible for structural designers to remove columns and increase design flexibility. All panels and connections were designed as per BS EN 1995-1-1:2004+A2:2014, NA to BS EN 1995-1-1:2004+A1:2008.  NA to BS EN 1995-1-1:2004+A1:2008  and ETA-07/0029. Floor panels were constructed using Kerto Q 37mm as a deck and Keero S 73x358 mm as a Ribs

The roof panels were constructed with 25mm Kerto Q and 45x300 Kerto S Ribs. Metsa Wood panels provide as well stability for the steel frame. Panels are connected to the steel and between each other using Rothoblaas screws. Some details required the steel to be flushed with the timber so top hung connection was implemented. This allow different levels of the steel and the same floor level.

The top hung detail was specially designed for the project with glued elements and screw reinforcement

The building’s facades are clad in timber, including its pitched roof derived from the unique form of the squash courts. The larch facade is referential to historic agricultural buildings in the area, while precise and refined detailing in anodised aluminium creates a familiar building that is completely contemporary in its context. Economic to build, the architectural language relates directly to its construction, using modular building elements to define its character, maximize its efficiency and ensure its future adaptability. High levels of insulation and natural ventilation throughout create a building that is highly sustainable.

As part of the strategic plan for the campus the new teaching space will allow Grade II listed boarding houses to be returned to their original use. The new building is positioned to complete and frame a new court for the campus which will form Cranleigh’s new academic heart. The timber panel were chosen not only for visual purpose but as well for the fast installation and lightness. Special coordination had to be considered for installation sequencing to allow for quick installation and low storage of elements on site. There was difficult access and small space As the steel had rough tolerance all Metsa Wood Ripa panels and details  had to be designed in such a way to allow for bigger tolerances within the steel. All panels were manufactured to exact Metsa specification with ifc information transferred to the panel manufacturer. All services in panels were predrilled to limit work on site and minimize damages. As most of the details were left exposed it was essential to provide solutions where connectors were not visible or partially hidden.