A high-performance screed was needed for the floors of Galliard Homes and O’Shea’s Baltimore Tower in Canary Wharf – so Tarmac answered the call.
Project: Baltimore Tower
Client: Galliard Homes
Main contract value: £142m
Main contractor: O’Shea
Screeding contractor: TCS Screeding
Concrete supplier: Tarmac
Canary Wharf is changing.
As one of the UK’s most iconic commercial developments, you wouldn’t normally associate it with housing.
All that is beginning to change. Canary Wharf Group is pushing ahead with plans to build new homes for private rent on its Wood Wharf site.
But just further down the road, a number of other high-rise developments are going up too, increasing the density of residences close to the London’s financial hub.
One of these schemes is Baltimore Wharf, developed by Galliard Homes.
The centrepiece of the scheme is the 46-storey, 150 m-tall Baltimore Tower, made up of luxury one, two and three-bedroom apartments.
O’Shea is the main contractor, with concrete supplied by Tarmac to specialist screeding contractor TCS Screeding.
When Construction News visited the site in September, 26 floors had been laid, with the concrete core stretching up above them from the middle.
The tower is already striking, twisting as it does up into the London sky.
From levels two to 37, the arrangement of apartments on the building’s interior is the same, while the outer balconies, of which each apartment has its own, shift slightly to create the appearance of a twist.
“It’s nothing like what it used to be – I remember all the rows of old houses”
Kevin Burr, Tarmac
Above level 37, there are fewer balconies on each floor to fit the smaller footprint. We’re standing on floor 24, admiring the view out towards Canary Wharf.
Tarmac special products co-ordinator Kevin Burr tells us how he grew up in this area, near Poplar.
“It’s nothing like what it used to be – I remember all the rows of old houses,” he says, conscious of the fact he’s now playing an integral role in helping replace those houses with giant towers such as this one.
Halving the building’s weight
Tarmac is supplying the screed for TCS Screeding to lay on the building’s floors. The screed in question is Topflow XTR, which is being supplied with a bespoke mix for this project.
Due to the tower’s unusual shape, the screed depth had to be reduced from a typical 65 mm using sand and cement, to around 30 mm on this development – something the Topflow product could accommodate.
In addition, the floors had a 60 kg/sq m load limit, another specification the bespoke mix satisfied.
First, a 5 mm rubber acoustic layer is put down onto the concrete floor, before the flowing screed is laid over the top at a depth of 30 mm, giving the 35 mm total depth.
By reducing the depth, the tower’s overall height is also lowered, saving time and money, with its weight also reduced by half.
The flowing screed has also proved much quicker to lay than a traditional sand-cement alternative.
“It takes us about 40 to 45 minutes to lay one 7 cu m lorry load,” says TCS Screeding contracts director Ed Valionis.
“One floor is approximately 240-250 sq m, so we do one floor in a day comfortably. It takes just 15 minutes to do one apartment.”
“Everyone wants to pour on a Friday. This means the screed can dry over the weekend and they can come and start work straightaway on Monday morning”
Ed Valionis, TCS Screeding
The screed is self-compacting, so a couple of site workers ensure the level is right using lasers, before using a dapple bar to level it out into a flat, smooth surface.
For the first 48 hours after this, the floor is sealed off from the elements to allow the screed to dry.
“Everyone wants to pour on a Friday,” Mr Valionis says. “This means the screed can dry over the weekend and they can come and start work straightaway on Monday morning.”
The other bonus provided by Tarmac’s bespoke screed mix is its strength.
Despite the low depth, the screed was required to have a 60 kg/sq m limit on its loading. It was also specified to be a C35 mix, with an F6 finish.
“We tested some of the material taken out of there,” says Tarmac special products co-ordinator Kevin Burr. “It ended up testing a lot higher than specified.”
On the day of our visit, there was due to be a load of screed delivered for the neighbouring 16-storey building adjacent to Baltimore Tower that forms part of the same development, but it was postponed while other trades caught up.
Nevertheless, the project is still progressing as planned and remains on course for completion in summer 2016.
Tarmac and TCS’s work on the screed will ensure the fit-out trades, when they take over, will make these apartments look like the luxury homes they’re destined to be – the next stage in Canary Wharf’s transformation.