Looking Back at The John Lewis Move to Exeter

Surveying a Stripped-Out Debenhams for a Major Refurbishment

In December 2010 we accompanied our client, the now defunct Midas Retail, on a tour of the recently vacated Debenhams store at Sidwell Street in Exeter, having began its life as Bobby’s in 1962 before becoming Debenhams in 1972. The site has been the subject of a soft strip out with no internal lighting and all shop fittings and internal cladding removed revealing a sorry looking building that now exposed the hand painted datums and column numbers from its original construction in the late 1960s. The building was a composite steel frame and concrete building with all steel columns encased in concrete.

John Lewis were due to move into the building in 2012 and the existing building was to be completely refurbished over all 9 floors. A new extension over the ground floor was to provide additional retail space on floors 1,2 and 3. The existing elevations were to be refurbished and re-clad to create a sleek modern looking building.

The Brief: Detailed Measured Building and Engineering Survey

A measured building survey of the building had been undertaken a couple of years earlier in 2008 for the building owners Land Securities. This however was whilst it was operating as a Debenhams store and prior to the strip out. To enable the detailed design to be undertaken our brief was to provide a detailed measured building and engineering survey of the stripped out building. Floor levels were to be observed on a 2m grid, ceiling plans to detail exposed beam locations and sizes were required as well as floor plans detailing exposed material types and column locations.

Establishing Survey Control in a Nine-Storey Building

The first task in January of 2011, in a near empty department store was to kit ourselves up with head torches and temporary lighting to establish survey control for our observations and for the setting out that would soon follow. Laser scanning was beginning to be more widely used in 2010 and whilst we had undertaken a number of point cloud surveys previously, we were not confident it would produce what was required within the tight time frames. Ironically 12 years later in 2022 and post Grenfell we found ourselves employing 3d laser scanners to undertake surveys of the elevations of the John Lewis to enable vital updates to the cladding.

Control is king in the world of survey however and in early 2011 we took advantage of the voids created in the floors when the escalators had been removed coupled with some floor cores that had housed M&E plant to traverse and laser plumb between floors. Closure was obtained with observations onto control and the streets surrounding the building. Similarly level datums were transferred with a digital level between floors.

Total Station Observations and Digital Photography

Control points were established on each floor with floor nails and retro targets to ensure there was plenty of redundancy should stations be covered or destroyed by the forthcoming construction work. Observations to walls columns and ceilings were undertaken with a reflectorless Leica Total Station and a bespoke code list in LSS software was created to ensure that wall finishes were identified as plaster, brick, concrete, tiled etc. An extensive number of digital photographs were taken to annotate CAD drawings to assist the London based architects and structural engineers.

Floor levels were observed with a digital level and contoured isopachytes were produce to analyse the level for tolerances with finishings.

Setting Out the Grid for the New Extension

Part of the brief included establishing the setting out grid to assist contractors with basic orientation and setting out. The Architect had based the grid on the 2008 survey that had columns that were heavily clad with shop fittings and this had been tied to the proposed fanned façade that would create the entrance and extension to three of the floors. Our surveys revealed that to enable the fan to correctly fit the front elevation the grid for the existing columns would be offset from the centre. The grid was orientated on a local north south grid for ease of co-ordination and the level datum taken from the 2008 survey that employed the top entrance step of Debenhams as its origin. Grids were subsequently marked on the concrete columns and floors with paint and permanent markers.

Ongoing Setting Out Through Construction

As construction work commenced it was necessary for us to visit the site regularly to provide setting out and survey updates. The extension works required the new steel frame to be bolted to the original. This required localised removal of the surrounding concrete to expose the steel frame. It was necessary to survey this frame to enable the new structure to be manufactured. This was a particularly challenging part of our work as the exposed elements were typically several floors above a suitable observation position and were exposed by no more than a few core holes. Data was collected by means of hidden point observations to several prisms that were then processed in bespoke spreadsheets to ensure accuracy and confidence levels were achieved. This enabled the new frame to be manufactured whilst the laborious and noisy task of removing concrete continued.

From Setting Out to Shop Fit-Out: Seeing the Project Through

The setting out works that were undertaken continued to the very end of the project when shop display lights were marked on ceilings and tile layouts marked on the floors. In between we had set out holding down bolts for the frame, plumbed cladding rails and lift shafts, marked penetrations for drainage and comms amongst a whole host of tasks that ensured that the new store opened its doors as planned in 2012.