Listed Buildings - Wire Sawing and Drilling Bank Vault

Listed Buildings - Wire Sawing and Drilling Bank Vault

Gnat-UK

C WIRE SAWING CASE STUDY Grade 1 Listed Building Bank of England Holding Vault Deconstruction

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Robotic Hydrodemolition in tandem with Wire Sawing

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Wire Sawing Procedures deployed to remove a reinforced Bank Vault in the basement of a Grade 1 Listed Building in London

Many older buildings in the major cities in the UK are routinely renovated and refurbished for private residential use. The example illustrated here is a Grade I listed building in the centre of London. The conversion necessitated the deconstruction of a heavily reinforced concrete basement which housed a former Bank of England holding vault. Being Grade I listed, strict constraints were imposed on the method of its removal. Diamond sawing and drilling proved to be the only acceptable way of completing the job on time and to the satisfaction of the client.

Whilst the walls and the roof of the building were built during the 16th and 17th centuries, the concrete walls and ceilings of the vault were added much later and were tied into the existing structure in the majority of areas. Operational Constraints The Project Engineer insisted that all work within the building should be non-percussive in order to preserve its structural integrity - this applied even to f ixing holes. The only method that was approved was diamond cutting since this gives the advantages of minimum vibration and noise and also reduces dust and debris.

HILTI Track Saw rigged for Vertical Cutting to isolate the Reinforced Vault walls into manageable sections to facilitate their removal from the basement

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Methodology DSA Members Gnat UK were given 6 weeks to complete the job using a combination of track sawing and stitch drilling to remove the walls, floor and ceiling. The walls and ceilings were 350mm thick and the floor nearer 700mm thick! All were heavily reinforced, especially the floor which had in fact been designed to resist diamond drilling! One metre square blocks were cut out and then removed using a 3 phase electric Brokk 90 robot modif ied for lifting. The blocks were transported to another holding area with the Brokk, where they were drilled and hydraulically burst into manageable sized sections to assist removal from the tight conf ines of the basement area. A total of just under 150 cubic metres of concrete was removed. Hilti Track Saws and Drill Rigs were used for the sawing and drilling. These provided the high power needed for an arduous task such as this. A number of suppliers were used for the consumables but in general Hertfordshire Diamond provided the 900mm diameter saw blades and Golz the I07mm diameter drill bits. The job was completed successfully with 2 days to spare and that included a hold up following the discovery of asbestos on site, when work was suspended for a week whilst the Asbestos was removed The main structure of the building was carefully monitored throughout the work to ensure no movement or damage was caused.

The occupant of the off ice on the other side of the party wall, an ex Prime Minister, was blissfully unaware of what was occurring only a few metres away!

Section after isolation. Concrete and Re-bar cut cleanly... and quietly!

Gnat UK Ltd Scotland Off ice Unit 1, Mid Friarton King James Business Park Perth PH2 8EL tel 01748 826046 fax 01748 826056 e-mail off [email protected]

Gnat UK Ltd Midlands Off ice Unit 7 Riverside Park East Service Road Raynesway Spondon Derby DE21 7RW tel 0844 840 4440 fax 01332 875836 e-mail off [email protected]

Gnat UK Ltd Southern Off ice The Old Lordship Farm Walkern Road Bennington Hertfordshire SG2 7LL tel 0844 840 5550 fax 01748 826056 e-mail off [email protected]