Keeping an old building is usually cheaper than replacing it outright.
Usually. The exception is when what you are keeping has to carry something it was never asked to carry.
A power station frame was designed to hold up boilers, turbines, coal handling gear and a roof.
It was never designed to hold floors full of people.
So the question on a job like this is not whether the old steel is sound.
It is whether the old steel is the right shape.
Two structures doing two different jobs
There is a standard way out of this and it is older than the conversion itself.
The answer that gets used on buildings like this is to stop treating it as one structure.
The original frame keeps doing what it always did, which is holding up the roof and bracing the walls, and it gets strengthened locally where the arithmetic is tight.
Everything new sits on its own foundations, threaded through the old frame without leaning on it.
That is why the piling matters more than it sounds. New piles were driven to about 164 feet, up to eight feet across, grouped into families by the loads they carry.
Some of the existing foundations were reused as well, which only ever works if you can prove what is actually down there.
The brick shell is the third element and the most delicate. It is not structural in the modern sense, so during demolition it was held by temporary props.
Those came out only once new steelwork was connected to the walls to restrain them permanently.
What is actually inside it now
The building sits on the south bank of the Thames at Battersea, in the borough of Wandsworth, opposite Chelsea rather than in it.
Around 250 apartments occupy the upper levels of the building, arranged around the roof and above the two turbine halls.
Below them sit six floors of offices, shops, an events space for 2,000 people, and a lift that runs up inside one chimney.
The total floor area comes to roughly 2.5 million square feet.
Two feature steel structures shaped like trees, about 300 tons each, hold up a column free space over the old boiler house.
One plated girder in there runs 89 feet long and nine feet deep, and weighs 62 tons on its own.
The chimneys were the part that went
Everything else about the building was retained wherever the engineers could argue for it.
All four were taken down and rebuilt as replicas, because the original concrete had degraded past repair.
Each replacement took about 600 tons of concrete, roughly 25,000 wheelbarrow loads, and the set used 400 gallons of paint.
New internal steel frameworks hold the replacements up.
Work on the building ran from 2012 to 2022, and the underground extension serving it opened in 2021.
Brick was the other slow job. Original imperial sized bricks had to be sourced from the firms that made them, and separate blends were mixed to match the color of each construction phase.
The station was built in two halves decades apart, so the brick differs across it.
Three claims that keep circulating
Three details about this building get repeated wrongly almost every time it is written about.
The first is the location. This is Battersea and not Chelsea, and the distinction matters to anybody using the story to find the place.
The second is the frame. The original steel was largely retained, including the western turbine hall trusses from the 1930s, with strengthening rather than removal.
Accounts of a corroded frame being stripped out wholesale and replaced with poured concrete have it almost exactly backwards.
New steelwork was added in enormous quantity, and the boiler house holds the largest share of it, but that is addition rather than substitution.
The apartment count also moves between 252 and 254 depending on the source, in the way that figures around a major crossing or an unusual build tend to drift a little, as the engineer’s own project record sets out.
What conversions like this actually sell
None of this arithmetic works at an ordinary price point, and it never has.
An apartment in a converted power station is never bought for its floor area.
It is bought for the wall behind it, and that is a genuinely awkward product to build, since heritage fabric resists insulation, service routes and modern window lines.
Every one of those constraints costs money that a new building would never have spent, and the sale price has to carry all of it.
Which is the honest reason these schemes end up at the top of the market rather than the middle, as the steel sector case study of the works describes.
The steel frame was never the expensive part of this building.
The brick around it was.
Read the whole thing?
Get the week's signal, not the noise
Our sharpest reporting on energy, climate and nature — free, once a week.
