Pyramid House, Farnborough

July 20, 2020

Cantillon were appointed by Steamrock capital & Catalyst Capital to undertake this full soft strip and demolition works package. The existing buildings on the site were typical of late 1980’s/ early 1990’s steel frame and concrete construction and consisted of 4 units; Pyramid House (three storey former office unit) and PC World, Jolen House and Oaklands House (low level former retail units).

Cantillon’s scope included the management and isolation of all M&E and the asbestos removal was undertaken in conjunction with the soft strip operations. The site was located in a busy retail park environment with a mixture of ‘live’ surrounding commercial & leisure industry properties including: Asda Superstore, B&Q DIY Centre and Farnborough Leisure Centre

An existing live UKPN network sub-station was located in the centre of the site. This was protected and remained operational for the full duration of the works.

Any incoming and outgoing service runs were scanned and marked clearly on site and protected for the full duration of the works.

During the works, additional supplementary scaffold protection was erected to structures being demolished to maintain the integrity of the live sub-station.

A tree survey report identified the requirement to protect certain tree’s on site and out further statutory obligations under the ‘Wildlife & Countryside Act 1981’ and the ‘Countryside and Rights of way Act 2000’. Works were undertaken with due care to ensure that these important features were not affected.

There was a project commitment to achieve a minimum of a ‘Very Good’ BREEAM rating and the demolition was delivered successfully in a manner which ensured that this was achieved.  This included a full Pre-demolition audit of the site to identify the main elements and implement a hierarchy of re-use and recycling of materials. We aim to re-use elements in their existing form wherever possible, and achieved a 96% diversion from landfill.

The demolition specification identified key structural considerations, particularly Pyramid House where the main lattice steel roof girders had a large span between external embedded steel column supports, with underslung steel trusses spanning perpendicularly below this to support the trusses that form the roof structure, and the large spans of the RC rib slabs below this. The demolition was carefully planned to ensure the continued integrity of the structure in the temporary condition.

Our general approach to the demolition of all buildings was by remote demolition methods with high-reach and standard reach demolition specification excavators.

Machines undertaking the demolition were all in the 45-ton range, with 25-ton excavators undertaking the processing and loading operations. 5-ton skid-steer loaders were used for horizontal transfer of some materials at ground level.

The dismantling of Pyramid House was undertaken using a 45-ton demolition specification high reach excavator with hydraulic pulveriser and rotating steel shear attachments. A 100-ton mobile all terrain crane was brought to site periodically to lift large sections of the main roof trusses. Whilst the load of the truss was supported by the mobile crane, the section was isolated by burners using oxy-propane cutting gear.

During the demolition process, water suppression was used in the form of fire hydrant hoses to continually dampen materials. A hose line was fed through the high reach excavator that sprayed over the attachment at high level, with a further manned hose used at low level to dampen materials. A dust boss water spray was also used to supplement these measures.

The remaining structures were lower level traditional steel portal frame structures, with RC elements and demolition was undertaken concurrently with the Pyramid House demolition, using standard reach 45-ton demolition specification excavators with larger hydraulic attachments and utilising the central processing and loading area.

Our team, including our in-house Structural Engineer – Simon Simpson and team of demolition experts, assessed the structure in the early stages and developed a detailed bespoke sequence and method.