Slabstress – Whitmore High School, Harrow

School rebuildSchool Rebuild

Harrow Council

Principal Contractor

Structural Engineer

Frame Contractor

Contract Duration
March to Sept 2009

PDF Download

In November 2006, Whitmore High School successfully bid for government money under the Building Schools for the Future funding and was awarded £32 million for a complete school rebuild.

The project would provide not just new facilities, modern classrooms and state-of-the-art equipment, but also allows for an extension of the already strong community use of the school in the evenings and at weekends. Harrow Council made a significant contribution to the facilities originally proposed so that there would be a large sports hall with spectator seating, as well as an extensive main hall and much enhanced dining facilities. External sporting facilities included a football pitch and a running track.

The new 9,550mÇ secondary school building was constructed in the grounds of the existing school, which was occupied throughout the construction period.

Freyssinet undertook the supply and installation of the 3S13 bonded post-tensioning system. The three storey structure had 300mm thick PT slabs. Structurally, some of the areas would have worked at 225mm depth, but 300mm had been specified as the minimum depth for acoustic reasons.

The building’s footprint resembled a crab’s claw, and the two main wings are consequently curved. Freyssinet used its three-strand bonded PT system which fits into a 20mm deep by 46mm wide galvanised steel duct. This was flexible enough to follow the curvature of the slab and proved more economic than adopting unbonded tendons, the conventional way of tackling high lateral curvatures.