{"id":506711,"date":"2024-10-02T10:23:03","date_gmt":"2024-10-02T09:23:03","guid":{"rendered":"https:\/\/www.constructionnews.co.uk\/?p=506711"},"modified":"2024-10-02T10:23:03","modified_gmt":"2024-10-02T09:23:03","slug":"cutting-and-carving-on-londons-oxford-street","status":"publish","type":"post","link":"https:\/\/www.constructionnews.co.uk\/project-reports\/cutting-and-carving-on-londons-oxford-street-02-10-2024\/","title":{"rendered":"Cutting and carving on London\u2019s Oxford Street"},"content":{"rendered":"
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Client:<\/strong> Publica
\nContract value:<\/strong> \u00a3132m
\nContract type:<\/strong> JCT
\nMain contractor:<\/strong> McLaren
\nArchitect:<\/strong> Studio PDP
\nStructural engineer:<\/strong> Civic Engineers
\nDemolition:<\/strong> Erith
\nPiling:<\/strong> Franki Foundations UK (subcontractor to Erith)
\nSteelwork:<\/strong> Severfield
\nMechanical, electrical and plumbing:<\/strong> Briggs & Forrester
\nMechanical and electrical consultancy:<\/strong> ChapmanBDSP
\nCrane and hoists:<\/strong> London Tower Cranes
\nFacade:<\/strong> Glaze Aluminium (new facades), PAYE (facade restoration)
\nStart date:<\/strong> February 2022 (pre-construction services)
\nExpected handover:<\/strong> Spring 2026<\/p>\n<\/div>\n

A new look for House of Fraser\u2019s ex-flagship shows there\u2019s life left in the UK\u2019s defunct department stores<\/strong><\/em><\/p>\n

A stroll down London\u2019s Oxford Street today tells a story of changing times for the UK high street. Covid lockdowns hit city centre economies hard, not least London\u2019s landmark shopping destination, which struggled to adapt to footfall falling off a cliff. Not only did the pandemic precipitate work-from-home mandates, which fuelled the inexorable rise of online consumption, but it also heralded the end of the traditional five-day office week, causing visitor numbers to plummet. This upended retail, killing off department stores and leaving their grand buildings standing empty \u2013 and in dire need of a new purpose. Now, efforts to remodel them, often into mixed-use commercial and leisure hubs, could yet breathe new life into these once-proud structures.<\/p>\n

One example is 318 Oxford Street, which was originally home to DH Evans and then House of Fraser until its closure in 2022. Completed in 1937, the original steel-framed, Portland stone-faced building comprised seven floors plus a basement, with 90 metre x 40 metre floorplates. Contractor McLaren is engaged in an extensive cut-and-carve project to create a mixed-use retail, commercial and leisure facility, designed by architect Studio PDP for client Publica.<\/p>\n

The \u00a3132m job includes the demolition of the top two storeys before being rebuilt with a brand-new eighth floor added on top. The original facade on the first five floors is being repaired and retained, with new windows installed. When it\u2019s handed over in spring 2026, the remodelled, BREEAM Excellent-rated building will feature 163,000sq ft of office space on floors two to seven. There will also be 42,000sq ft of retail space on the ground and first floors, 29,000sq ft for leisure facilities (including a gym and swimming pool) in the basement, and an 18,000sq ft top-floor restaurant.<\/p>\n

McLaren has a track record of cut-and-carve projects in London, but 318 Oxford Street is \u201ca larger-scale version of what we\u2019ve previously undertaken\u201d, says McLaren project director Simon LeFevre.<\/p>\n

Early worries<\/h3>\n

Planning permission was granted by Westminster Council in November 2021 and McLaren is delivering the job under a two-stage tender, including a pre-construction services agreement.<\/p>\n

Before McLaren was appointed, an initial survey found some failing elements in the facade so the building was covered in netting as a safety measure. Some spandrel panels were cracked, but a subsequent drone inspection found the original facade was in better condition than originally thought.<\/p>\n

When enabling works began, the building\u2019s interior bore visible reminders of its recent past, with shelves, other standard fittings and even some stock left behind. \u201cIt took us a while just to get rid of that before we could even start the soft stripping [demolition by Erith and removal of interior fixtures],\u201d LeFevre recalls. \u201cThat\u2019s what we\u2019ve been doing predominantly over the last two years: getting the building into some sort of condition to allow us to start the new works.\u201d<\/p>\n

Most internal masonry walls were removed in the demolition phase. So were the escalators serving all the floors in the old department store, leaving voids in the central and northwestern sides of the building.<\/p>\n

\u201cThe original building, as is normal for 1930s buildings, didn\u2019t have any structural cores as such but relied on lots of brick masonry walls built between the steel frame for stability,\u201d according to a spokesperson for structural engineer Civic Engineers. \u201cWe have taken most of those walls out to create open-plan space, so a new structural core was designed to take all the lateral loads on the building. It was most efficient to put the new structural core into that void rather than having to do more demolition.\u201d<\/p>\n

Civic Engineers designed the completely new central stability core with a braced 17×8 metre steel frame, weighing 260 tonnes and inserted into the former escalator well. It rises 31.8 metres from the basement mezzanine level to the sixth floor.<\/p>\n

Time saver<\/h3>\n

McLaren originally intended to work on the central stability core and a northwestern stair core separately \u2013 but it refined its strategy following discussions with Civic, Erith and temporary works designer Swanton. \u201cNow, we have temporary works in place to allow us to do both simultaneously, which has saved the client time,\u201d says LeFevre. \u201cIt really took some of the risk out of the project for the client. Otherwise, we could be looking at taking a lot longer to finish and would only just be starting the demolition now.\u201d<\/p>\n

A single Saez SLH 205 hydraulic luffing jib, provided by crane-hire firm London Tower Cranes, is mounted on four original columns on the fifth floor of the existing structure. \u201cIt was one of the items we put in early using a mobile crane, before the demolition began,\u201d says McLaren project manager Colin Sanders. The tower crane rises to 86.9 metres and can lift the 24 x 4 tonne steel columns, the heaviest items in the stability core.<\/p>\n

Alterations were needed to the existing foundations. A new concrete slab was required in the basement after the foundations were exposed to help inform Civic\u2019s pilot design. The new slab is 110cm deep and formed from three pours. It is connected via rebar and couplers, and integrates piles and a reinforced concrete raft to accommodate loads. Piling specialist Franki Foundations drove 47 continuous flight auger
\npiles (450mm wide), at least 17.5 metres long and 15 metres deep.<\/p>\n

In the basement, mechanical and electrical subcontractor Briggs & Forrester is installing a central low-temperature hot water plant with six boilers. Floors one to four will have their own air-handling units, while floors five and above will be fed from centralised air-handling units on the roof.<\/p>\n

The open-plan Cat A offices on floors two to seven will have exposed soffits featuring the original concrete I-beams \u201cin very narrow sections\u201d, LeFevre says. Originally, the beams were laid on top of steelwork with a concrete socket. \u201cThe problem is that the [steel] reinforcement to the underside of the concrete beams hasn\u2019t got a lot of concrete covering it for fire protection,\u201d he adds. For flame retardation, all the soffits are being sprayed by firestopping specialist Euroside Construction.<\/p>\n

Work on the fifth floor includes reinstatement of the stone facade by subcontractor PAYE, which also raised the window heights by 300mm. On the sixth floor, McLaren was putting the final touches to the north-west corner when Construction News <\/em>visited in June. Originally, the sixth-floor slab had a 1.5 metre step down around the perimeter. That has been brought back up to the same level as the rest of the floor, delivering a floor-to-ceiling height of 2.97 metres. The resulting flat floorplate enables the recently raised space to be used as a terrace, says Sanders.<\/p>\n

On the top floor, the facade comprises aluminium curtain wall frame sections. The roof parapet is a steel frame construction wrapped with cement-bonded particleboard plus insulation and waterproofing layers. The parapet and adjoining canopy are faced with reconstituted stone rainscreen cladding from facade systems manufacturer Shackerley.<\/p>\n

Reusing steel<\/h3>\n

Two tonnes of original steel columns have been reclaimed by steelwork subcontractor Severfield before their reinstallation in the top-floor restaurant. They are shot-blasted and coated with intumescent paint by Euroside. Severfield provided 1,250 tonnes of structural steel in total \u2013 600 tonnes was to refurbish the existing structure, with 650 tonnes for the new floors, including 440 tonnes of Fabsec cellular beams. Ten of the 21 steel columns from the original building are being reused by Willmott Dixon on an office retrofit job near Tower Bridge. Reusing 80 tonnes of columns in this fashion rather than turning them into scrap should save 20 tonnes of carbon, say Civic and McLaren.<\/p>\n

Green materials on the roof will include pre-grown sedum turf. The roof will also feature a liquid-applied waterproof covering, a protection sheet and waterflow-reducing layer, XPS insulation boards and a top layer of gravel. Briggs & Forrester is providing roof-mounted air-source heat pumps, a 750kVa rooftop standby generator and solar panels capable of generating 18kWp.<\/p>\n

\u201cWe\u2019re approaching the conclusion of the structural reinstatement to the existing building,\u201d says LeFevre. \u201cIn the second half of this year, we\u2019ll start erecting steel to the [new] upper floors. And simultaneously within the existing building we\u2019ll prepare for fit-out in 2025. It\u2019s a bit like an enabling-works process over the next six to eight months \u2013 but once fit-out starts, you\u2019ll see activity skyrocket.\u201d<\/p>\n

\n

Checking on the carbon<\/h3>\n

Civic Engineers estimates that the structural aspects of the 318 Oxford Street scheme will produce 3,374 tonnes of embodied carbon \u2013 but it has designed ways of minimising the footprint. \u201cI was keen we looked at the new-build elements in isolation to check we weren\u2019t hiding some profligate use of carbon in them behind the fact that most of the structure is retained,\u201d says the firm\u2019s associate director, Simon Bennett. \u201cAs you would expect, for a refurb, the overall figures are pretty good, but the new-build figures aren\u2019t bad either, which gave us confidence we were designing them efficiently.\u201d<\/p>\n

Measures to reduce carbon intensity have included a minimum of 50 per cent GGBS (ground granulated blast-furnace slag) for all ready-mixed concrete used instead of 100 per cent conventional cement, and a 56-day compressive strength test for the foundation concrete instead of 28 days. \u201cThe extra month allows you to take advantage of extra strength gain, and so reduces the cement content needed in the mix \u2013 which is where the vast majority of the carbon is,\u201d says Bennett.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Client: Publica Contract value: \u00a3132m Contract type: JCT Main contractor: McLaren Architect: Studio PDP Structural engineer: Civic Engineers Demolition: Erith Piling: Franki Foundations UK (subcontractor to Erith) Steelwork: Severfield Mechanical, electrical and plumbing: Briggs & Forrester Mechanical and electrical consultancy: ChapmanBDSP Crane and hoists: London Tower Cranes Facade: Glaze Aluminium (new facades), PAYE (facade restoration) …<\/p>\n","protected":false},"author":135716,"featured_media":506724,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ep_exclude_from_search":false},"categories":[557],"tags":[],"yoast_head":"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\t\n\t\n\t\n