The Cost of a Clear Span
Why we take a storey out of a building rather than put a column into a floor plate.
A column in the middle of an office floor costs almost nothing to build and constrains the plan for the life of the building. Removing it costs a great deal and constrains nothing. That trade is the single most consequential decision in a commercial scheme, and it is usually made by whoever is holding the cost plan rather than by anyone thinking about the next forty years.
The arithmetic is unforgiving. Going from a twelve-metre span to eighteen deepens the beams, which raises the floor-to-floor height, which either loses you a storey within the same envelope or pushes you past a planning height you will not get. At Gantry Works it cost a full floor.
We took the floor out. A tenant can plan an eighteen-metre clear field any way they want, and will be able to in 2064. Nobody has ever thanked a developer for the storey they squeezed in.