Contractor has employed a progressive construction approach to save Oldham Town Hall from falling apart.
Project: Oldham Town Hall restoration
Client: Oldham Council
Contract value: £36m
Main contractor: Morgan Sindall Construction & Infrastructure
Temporary works: Mabey Hire
Masonry / stone restoration: Stone Central
Steelwork subcontractor: Carnaby Steel Structures
Start date: October 2013
Completion date: May 2016
Just six years ago, Oldham’s Grade II-listed town hall was described by conservation charity the Victorian Society as “in desperate need of a saviour”.
Built in 1841, and graced by Winston Churchill when he was elected local MP in 1900, the building was boarded up in 1995.
Step forward Morgan Sindall.
The Victorian Society described the building as “riddled with wet and dry rot”, with “dangerous” floors and a roof “at risk of collapse”.
Morgan Sindall contracts manager Ben Cushway will say its condition wasn’t even as good as that.
Mr Cushway and his team started working with the council in 2013 on the feasibility of bringing the town hall back to life.
What they found inside the building was even worse than expected, but two years later the restoration project is up and running, with the goal of reopening the historic structure next spring.
Where once lived council offices and a courtroom, there will be restaurants, shops and a seven-screen cinema.
Built on rocks and boulders
A modern extension will bring the building into the 21st Century with a flourish, but many of the interior and exterior heritage features will remain.
And herein lay a sizeable challenge.
“It was dilapidated and uncared for – even worse condition than we expected,” Mr Cushway says.
“There’s a lesson to be learnt that what you see on the surface is not what you see underneath. You really have to explore deep with structures like this.
“There was a massive amount of dry and wet rot, extensive pigeon mess throughout the corridors, lead paint and asbestos.
“There were no foundations as such, it was built on boulders and rocks.”
“We convinced the client to spend quite a few million to do progressive construction and deconstruction works to open up areas we needed to look at”
Ben Cushway, Morgan Sindall
Morgan Sindall was initially appointed to carry out a number of surveys to establish the true condition of the building, and to subsequently develop the scope of works.
“What we found was that to get to the crux of the structure we had to start construction works, so we convinced the client to spend quite a few million to do progressive construction and deconstruction works to open up areas we needed to look at,” Mr Cushway says.
“To do that we had to do a lot of partial discharge of planning conditions with detailed methodologies and say why we wanted to take plaster off a wall and so on.”
Chicken and egg design
English Heritage was a key consultee to the council, which controlled the planning process. This led to a major onus on preservation from a very early stage in the scheme.
“Justifying some of the work we were doing without the final detail of the scheme was difficult,” Mr Cushway says.
“We had to do the work to develop the detail, but we needed the detail to justify the work.”
Enabling works were due to finish in May 2014, but snowballed and did not complete until October that year. “They grew to the extent that we were in fact doing second stage works in the first stage to inform cost, scope and planning discharge in a timely way,” Mr Cushway adds.
“Fundamentally we wanted to de-risk the project at enabling stage. It ended up taking a year, which is a little disproportionate to the project size, but then so is the complexity of the scheme.”
To get a discharge notice, a raft of documents and photographs were needed for each isolated job.
“We had to present all the other options we had considered and the reasons for discarding them,” Mr Cushway says. “My role became very administrative; very heritage and risk-management focused.”
Second stage works finally began on site in October 2014, with a finish date fixed for spring 2016.
On the plus side, a lot of work had been done – a number of floors had been demolished; façade retention and plan bracing put in; and even some piles put down.
Major foundations challenge
Foundations were a major challenge, given the quality of those already in place.
“The original design was for concrete pad foundations, but we had concerns these would transfer load on to the existing foundations and structure,” Mr Cushway says.
“Yet we could not get a normal piling rig in because of the small doorways.
“We eventually found a small piling rig that could do the job. It was very intricate, confined-space working.”
At the same time, internal bracing was needed to keep the structure standing while internal floors and some walls were removed.
“Even to get the temporary structure in, we had to do temporary temporary works,” Mr Cushway says.
“Where we were removing internal walls to make bigger spaces, we had to break through intermediary walls to get braces in. In some cases we had to put lintels through.”
Getting the final steel for the new floors in through the mesh of existing walls and temporary bracing called for calculated design. There were a number of factors to consider in terms of performance, buildability and manufacture at this stage.
“There was immense coordination between the temporary works contractor and the steel fabricator. The point cloud surveys and the Revit model came into their own,” (see box).
Once all the temporary bracing was in place from the bottom up, site workers removed the roof, with the exception of the main trusses in some areas.
Old floors were removed, from the top down, before steel was craned in through the gaps in the roof, through the scaffolding and through the plan bracing to be rested on the foundations.
“We had to weave the steel beams in, guiding them subtly into place while they were supported by the crane. It’s delicate and you can’t bang into precious finishes or structurally important elements.”
This stage of works is ongoing, with permanent steel going into place according to the requirements of each area of the building.
“We split the project into six zones, and each has a different challenge,” Mr Cushway says.
“Each zone has a different approach because it has been built with different construction techniques and has different original structures.”
“We’re still trying to make the structure sound, and we’ve learnt that unforeseen circumstances are a risk”
Ben Cushway, Morgan Sindall
In late March, permanent steel was going in for the floors, stone remedial works and window repairs were ongoing, and operatives were piling for the new build extension.
A multitude of specific strengthening works were also under way to bring the building up to the necessary level.
“A lot of the new weight passes through the existing structure, and we found a lot of cavities, fireplaces and so on that require grouting or fixing in various ways,” Mr Cushway says.
The new build steel work will begin in June, with glass cladding to follow. The main challenge here is the interface with the existing structure, which is built into a hill and has various details on its exterior walls.
The project is on target for completion next spring but the project team is acutely aware of how much remains to be done.
“We’re still trying to make the structure sound, and we’ve learnt that unforeseen circumstances are a risk,” Mr Cushway says.
“Every day is a challenge, every day we come across a clash. But it is rewarding.
“We have a good team that have taken the project by the scruff and are doing a great job.”
Modern technology applied to old building
With so much design and planning intricacy involved in the scheme, technology has a major role to play.
“We did a point cloud survey, which uses a spinning laser in the middle of the room to record a space in infinite detail and colour,” Mr Cushway says.
“When it’s put into the right software, it allows you to zoom in to an elevation to the point where you feel you’re touching it. This gives you millimetre by millimetre measurements of existing features.
“This supported discharge of planning conditions relating to recording what was there. It also gives some of our subcontractors the ability to replicate some of the materials we had to take out.”
Point Cloud information was also put into an Autodesk Revit model.
“This gives you very accurate information on details like how out-of-square the plumbing room is, and how thick the dividing walls are in different places.”
As well as the challenges of removing and replacing elements of the historic building, many of the retained finishes needed protective cases, from glazing to door linings to banisters.
In the town hall’s Egyptian room, missing wall tiles have to be replaced by authentic looking replicas.
“We may need 3,000 tiles and there are probably 27 different profiles,” Mr Cushway says.
“Every feature on the new tile needs to be 8 per cent bigger than the original because it will reduce by that amount when it’s fired.”
Samples of replica items are needed for approval, yet a full discharge of planning conditions is often not given until the final product is in place.
“Just to put some bricks into a failing wall, I’ve had to sample every brick from every wall on the job to get the general strength, so we can get replicas to the same strength,” Mr Cushway says.
“I’ve had to do the same tests for the mortar, along with composition of what the mortar contains. Every item of work is bespoke and has to be justified,” he says.
“We are very tuned into conservation now.”