Project Brief
We provided civil and structural design services for a new 11-storey, 58-unit, concrete-framed apartment building on a restricted urban site adjacent to a live railway line.
We provided full frame design and reinforced concrete detailing for the project, including shear walls, cores, flat slabs and piled foundations. Adept also provided full below-ground drainage designs and advised on ‘blue roof’ specifications which led to a reduction in storm water attenuation below ground, on what was a very tight site. We also reviewed the Geo-environmental, SuDS, Fire, Services and Demolition reports undertaken for the previous planning application and contributed to a new application detailing proposed alterations.
The building’s footprint uses two repeating stacked floor plans for floors 1-5 and 8-10. Floors 6 and 7 accommodate circulation, and floor 11 contains flats, amenity space, plant, air source heat pumps and a sprinkler tank.
Solution
At initial design stage we explored steel framing solutions but the steelwork led to an increase in total floor depth which pushed the total height of the building over the approved planning scheme. There was also no speed advantage because a tight boundary restricted working space, so in situ concrete columns were specified instead of precast columns. Due to the site’s proximity to a railway line, we coordinated with a rail engineering consultant to secure Network Rail’s approval via CAT 3 checks and to ensure work proceeded to the programme.
We proposed piled foundations, 250mm deep flat slabs and concrete shear walls and a CFA pile solution, all of which were designed by specialists. We ensured that piles to the rear were offset to ensure piling rig locations met with the approval of Network Rail. We used Etabs and Robot software to design the main structure, and REVIT to coordinate with the architect and keep the shared IFC models updated with column positions and sizes.
Plastic cell attenuation tanks in the parking undercroft allow surface water to be stored in collaboration with the ‘blue roof’ solution. A rate restriction was agreed with the LLFA and Southern Water for discharge to the public sewer.
A brick-clad external finish was desired but, to avoid increasing wall thickness and additional weight, we advised that a specialist cladding designer be engaged to provide a suitable product that would be both fire resistant and provide lateral wind restraint. In the end, an SFS system was selected. We also explored proposals for a PV array.
