Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to the newest version of your browser.

Your browser appears to have cookies disabled. For the best experience of Construction News, please enable cookies in your browser.

Welcome to the Construction News site. As we have relaunched, you will have to sign in once now and agree for us to use cookies, so you won't need to log in each time you visit our site.
Learn more

Walkie Talkie scaffolding takes to the air

Brogan Group took on the job of working 176 m above City streets below on one of London’s most unusual and high-profile façades.

Overall project value: £500m

Joint developers: Canary Wharf Group & Land Securities

Construction manager: Canary Wharf Contractors

Sky garden façade contractor: Gartner

Sky garden scaffolding contractor: Brogan Group

Architect: Rafael Viñoly

Height: 176.7 m

20 Fenchurch Street, commonly known as the Walkie Talkie, opened the doors to its Sky Garden this month.

A key part of securing planning approval, the Sky Garden is a public space occupying the building’s top three floors (35-37) and is free to access for members of the public, albeit with advance booking required.

With 360-degree views from the garden, the views afforded from here are panoramic, looking back at the cluster of skyscrapers to the eastern edge of the City of London.

These include the Cheesegrater and the Gherkin, with uninterrupted views towards the south and west as well.

Garden in the sky

Constructing the Sky Garden, however, was no easy task.

The building’s most obvious distinctive feature is its unusual shape.

Growing wider as it moves upwards, the building bulges out at the top.

This takes advantage of the fact that commercial rents are higher the further off the ground you climb, as well as affording more space at street level for the expected numbers of visitors.

To support the shape of the bulbous roof, the team built a series of steel fins across the top of the structure.

The client employed Gartner, part of the Permasteelia Group, to undertake the cladding and façade works for the Sky Garden.

“When you work out above most buildings externally, you can see straight down the façade. Here you were standing out in fresh air”

Giles Williamson, Brogan Group

Gartner in turn contracted Brogan Group to carry out the scaffolding works required to support this.

“Gartner approached us to come up with an initial scheme,” Brogan Group director Giles Williamson explains.

“The works consisted of constructing propping scaffolds internally, so that wherever there was a fin there was a scaffold underneath it propping it up.”

These scaffolds went all the way across the building internally, with the team beginning on the southern elevation and moving to the north.

The team also installed lateral support towers on the east and west ends of the 35th floor to support the fins.

Once each fin settled, the team removed the tower underneath it, allowing cladding and glazing work to begin.

Cantilever challenge

Perhaps the most technically complex and somewhat eye-watering element of the project involved cantilevered scaffolding out over all four external elevations of the building.

In particular, the building’s concave shape on the southern elevation, facing the River Thames, presented a unique situation.

“When you work outside the building envelope, you can see straight down the façade,” Mr Williamson says.

“Here you were standing out in fresh air. It was a challenge for the scaffolders, as you were 140 m or so up in the air.

“It was a challenge to make sure we had the right people up there, who we could trust – as obviously anything dropped from that height could be fatal”

Giles Williamson, Brogan Group

“That meant we could only have the best scaffolders out on it and those that weren’t afraid of heights.

“It was a challenge to make sure we had the right people up there, who we could trust – as obviously anything dropped from that height could be fatal.”

This cantilevered structure on the south side had to sail out from the building and was designed to support the large end fin, known as fin one, which hangs out over Eastcheap Street below and weighs more than 15 tonnes.

“This scaffold on the southern elevation was a beast,” Mr Williamson says.

“The design was predominantly driven around Gartner’s requirements and what they needed to do the work.”

Fin one was one of the largest fins, which meant the scaffold required to support it was also particularly large and complex.

“Gartner needed to be able to access both sides of the fin, which necessitated working outside the building line,” he adds.

External cantilevered scaffolds were also required to the north, east and west elevations.

These comprised a cantilevered horse scaffold out of the building at level 35 with a ‘punched-up’ independent scaffold.

Highly safe

Brogan Group also had to consider health and safety particularly closely, thanks to the extremely high elevations and the high-profile nature of the job.

The team worked a total of 44,160 man-hours with no RIDDORS, resulting in an accident frequency rate of zero.

The building’s unusual shape created the main risks that the team had to consider.

The aforementioned cantilevered scaffolds meant work was being carried out some 150 m above the ground and directly over the street below.

Once out, the team would punch up and continue the scaffold access up the required height at the top of the fins, some 14 to 16 m above.

“Pretty much every precaution imaginable was taken. Nothing went wrong, nothing was dropped”

Giles Williamson, Brogan Group

To minimise risk as much as possible, Brogan Group assembled the cantilevered section on the building slab before it was pushed out into the open air, with debris netting fitted around and beneath it to form a catchment around the working area.

“Safety nets and debris netting were used, and all equipment was tethered,” Mr Williamson explains.

“Everything was tied before erected, so everything was on ropes – that’s unusual, as you wouldn’t normally erect in that manner.”

As well as the netting, the team fitted localised monarflex sheeting to the outside face of the scaffold to prevent scaffolders from accidentally dropping tools or materials over the edge.

Combisafe fans were also used at all sides of the building to protect the public below as the scaffolds went up.

A large portion of the work was carried out at night, particularly during the second half of the project programme, ensuring that fewer people were on the streets below.

“Pretty much every precaution imaginable was taken,” Mr Williamson adds. “Nothing went wrong, nothing was dropped.”

Scorch leads to close inspection

Pre-assembly on the slab was not without its challenges either, though.

As the Sky Garden is designed to mimic a grassy hill, the concrete slab between the 35th and 37th floors was actually a steep slope.

This meant operatives had to take extra care when moving materials to and from working areas.

In addition, lifting materials from ground level to the 35th floor was carried out with tower cranes.

Each lift was affected by wind, which was often much stronger at that height than at ground level.

“Clear communication between all those involved in the lifts was key,” Mr Williamson says.

“When there was the issue with scorching cars on the pavement below, it was all over the press and everyone was looking up at us working”

Giles Williamson, Brogan Group

Developer Canary Wharf Group is “one of the most demanding clients” out there, he adds, particularly with the firm using Canary Wharf Contractors to carry out the build.

“On health and safety, we had to abide by both Gartner’s and Canary Wharf Group’s demands,” Mr Williamson says.

“This wasn’t a problem but it was a challenge, as everyone was looking at the building.

“And when there was the issue with scorching cars on the pavement below, it was all over the press and everyone was looking up at us working.”

The team operated an intense inspection regime to ensure minimal issues with this, helping to meet both the main contractor’s and client’s expectations during their inspections.

Lessons learned

Brogan Group has learned much from the project, one of the most technically complex and high-profile it has had to undertake recently.

It employed expertise gained on the Beethan Tower project for Carillion in Manchester.

“That building was about 35 floors and they suddenly realised they needed a fin putting on top of the building – that was also technically challenging with some of the same issues,” Mr Williamson says.

“It was even windier there in fact, so we were able to take what we learned to that job.

“It’s unusual to get a scaffold at that height.”

This proven track record helped Brogan Group win the job, to the point that it was the only company Gartner approached.

“I don’t think there’s many scaffold companies who could do such a technically challenging project from a design point of view and a construction point of view,” Mr Williamson says.

The Sky Garden is now open to the public, and despite some negative reviews from architecture critics and criticism over the fact that advance booking is required, it has resulted in one of London’s only free-to-access viewing gallery in a tall building.

Without the complex solution developed by Brogan Group, constructing the Walkie Talkie’s unique roof would not have been possible.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Links may be included in your comments but HTML is not permitted.