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In the City of London's busy Old Street roundabout area, we carried out a number of works for two 1960s office buildings.
The finished result is Victorian-esque, incorporating a brick façade and exposed concrete ceilings. It offers more than 100,000 sqft of office space along with room for shared amenities and retail outlets and achieved net zero carbon construction.
Our works included soft strip, asbestos removal, structural demolition, pile probing, UXO magnetometer survey and the installation of a piling platform within the existing basement box. Two substantial discoveries were overcome with minimal impact to the programme.
Demolition
Logistical Constraints
02
With most inner-city jobs in busy pedestrian and traffic areas, there are times when street side scaffolding and pavement gantries need to be erected and dismantled out of normal hours. For this project, we did so with the agreement of Islington Council and prior notification to local residencies. To manage logistical and spatial constraints, a 50 m pit lane was also constructed along Featherstone Street while maintaining a two-way cycle lane in the road.
Asbestos Discovery
03
The original R&D survey excluded the window frames. Once site set-up was complete, some window frames were removed under controlled conditions to close out this exclusion. Numerous packers were exposed in each window reveal, making this the first asbestos discovery.
Our project team re-sequenced the programme with the scaffold access amendments and demolition re-phasing to minimise EoT duration to remove asbestos packers from 736 windows. Our in-house asbestos team worked diligently to implement this plan.
Demolition & Enabling
04
Demolition started and ended with traditional top down techniques using internal material drop zones to limit the effect of noise, dust and vibration to the residential, business and open park outside.
A gravity block was constructed adjacent to Matisse Court & Lexington Apartments to remove lateral loading generated by the 2.3 m deep pile mat and piling works. At tender stage, a 4 N/mm2 concrete mix was agreed. However, after contract award, the follow-on piling contractor stipulated a weaker 2 N/mm2 mix. Following talks with the client team on risk ownership, we successfully developed the alternative concrete mix alongside concrete suppliers and the piling contractor with cube test results verifying strength gain for the 400 m3 placed.
During the pile probing process, we discovered a number of piles that affected the design pile layout. Collaborating closely with Derwent’s structural engineer HTS, we surveyed, plotted and found alternative locations for the affected piles while minimising programme impact to the follow-on piling contractor. 98% of all materials removed from the site were diverted away from landfill.
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Asbestos Discovery
03
The original R&D survey excluded the window frames. Once site set-up was complete, some window frames were removed under controlled conditions to close out this exclusion. Numerous packers were exposed in each window reveal, making this the first asbestos discovery.
Our project team re-sequenced the programme with the scaffold access amendments and demolition re-phasing to minimise EoT duration to remove asbestos packers from 736 windows. Our in-house asbestos team worked diligently to implement this plan.
Demolition & Enabling
04
Demolition started and ended with traditional top down techniques using internal material drop zones to limit the effect of noise, dust and vibration to the residential, business and open park outside.
A gravity block was constructed adjacent to Matisse Court & Lexington Apartments to remove lateral loading generated by the 2.3 m deep pile mat and piling works. At tender stage, a 4 N/mm2 concrete mix was agreed. However, after contract award, the follow-on piling contractor stipulated a weaker 2 N/mm2 mix. Following talks with the client team on risk ownership, we successfully developed the alternative concrete mix alongside concrete suppliers and the piling contractor with cube test results verifying strength gain for the 400 m3 placed.
During the pile probing process, we discovered a number of piles that affected the design pile layout. Collaborating closely with Derwent’s structural engineer HTS, we surveyed, plotted and found alternative locations for the affected piles while minimising programme impact to the follow-on piling contractor. 98% of all materials removed from the site were diverted away from landfill.
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Asbestos Discovery
03
The original R&D survey excluded the window frames. Once site set-up was complete, some window frames were removed under controlled conditions to close out this exclusion. Numerous packers were exposed in each window reveal, making this the first asbestos discovery.
Our project team re-sequenced the programme with the scaffold access amendments and demolition re-phasing to minimise EoT duration to remove asbestos packers from 736 windows. Our in-house asbestos team worked diligently to implement this plan.
Demolition & Enabling
04
Demolition started and ended with traditional top down techniques using internal material drop zones to limit the effect of noise, dust and vibration to the residential, business and open park outside.
A gravity block was constructed adjacent to Matisse Court & Lexington Apartments to remove lateral loading generated by the 2.3 m deep pile mat and piling works. At tender stage, a 4 N/mm2 concrete mix was agreed. However, after contract award, the follow-on piling contractor stipulated a weaker 2 N/mm2 mix. Following talks with the client team on risk ownership, we successfully developed the alternative concrete mix alongside concrete suppliers and the piling contractor with cube test results verifying strength gain for the 400 m3 placed.
During the pile probing process, we discovered a number of piles that affected the design pile layout. Collaborating closely with Derwent’s structural engineer HTS, we surveyed, plotted and found alternative locations for the affected piles while minimising programme impact to the follow-on piling contractor. 98% of all materials removed from the site were diverted away from landfill.
05
06
07
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06
06
click to open
Asbestos Discovery
03
The original R&D survey excluded the window frames. Once site set-up was complete, some window frames were removed under controlled conditions to close out this exclusion. Numerous packers were exposed in each window reveal, making this the first asbestos discovery.
Our project team re-sequenced the programme with the scaffold access amendments and demolition re-phasing to minimise EoT duration to remove asbestos packers from 736 windows. Our in-house asbestos team worked diligently to implement this plan.
Demolition & Enabling
04
Demolition started and ended with traditional top down techniques using internal material drop zones to limit the effect of noise, dust and vibration to the residential, business and open park outside.
A gravity block was constructed adjacent to Matisse Court & Lexington Apartments to remove lateral loading generated by the 2.3 m deep pile mat and piling works. At tender stage, a 4 N/mm2 concrete mix was agreed. However, after contract award, the follow-on piling contractor stipulated a weaker 2 N/mm2 mix. Following talks with the client team on risk ownership, we successfully developed the alternative concrete mix alongside concrete suppliers and the piling contractor with cube test results verifying strength gain for the 400 m3 placed.
During the pile probing process, we discovered a number of piles that affected the design pile layout. Collaborating closely with Derwent’s structural engineer HTS, we surveyed, plotted and found alternative locations for the affected piles while minimising programme impact to the follow-on piling contractor. 98% of all materials removed from the site were diverted away from landfill.
05
06
07
08
09
10
Asbestos Discovery
03
The original R&D survey excluded the window frames. Once site set-up was complete, some window frames were removed under controlled conditions to close out this exclusion. Numerous packers were exposed in each window reveal, making this the first asbestos discovery.
Our project team re-sequenced the programme with the scaffold access amendments and demolition re-phasing to minimise EoT duration to remove asbestos packers from 736 windows. Our in-house asbestos team worked diligently to implement this plan.
Demolition & Enabling
04
Demolition started and ended with traditional top down techniques using internal material drop zones to limit the effect of noise, dust and vibration to the residential, business and open park outside.
A gravity block was constructed adjacent to Matisse Court & Lexington Apartments to remove lateral loading generated by the 2.3 m deep pile mat and piling works. At tender stage, a 4 N/mm2 concrete mix was agreed. However, after contract award, the follow-on piling contractor stipulated a weaker 2 N/mm2 mix. Following talks with the client team on risk ownership, we successfully developed the alternative concrete mix alongside concrete suppliers and the piling contractor with cube test results verifying strength gain for the 400 m3 placed.
During the pile probing process, we discovered a number of piles that affected the design pile layout. Collaborating closely with Derwent’s structural engineer HTS, we surveyed, plotted and found alternative locations for the affected piles while minimising programme impact to the follow-on piling contractor. 98% of all materials removed from the site were diverted away from landfill.
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