Cost-effective industrial cladding is being put to its first-ever residential use in a controversial housing-for-the-homeless project.
Sending in the bulldozers sometimes seems the kindest thing you can do to a building. But, as Socrates Miltiadou points out, flatten a tower block and you shoot yourself in the foot on floorspace if you don't get planning permission to build another tower in its place. "We have to keep the ones we've got," says the director at Papa Architects. "If you have a tower, make it beautiful."

Miltiadou is refurbishing Point West, an almost derelict nine-storey office block just off the high street in Hayes, Middlesex, and converting it into a hostel. The project represents the first residential use in the UK of Finnish company Paroc's cladding.

"It's a fantastic system," says Miltiadou. "It's cheap, simple and looks fabulous. It does everything a cladding system should do, but most budget systems don't. There are two ways of overcladding a tower block: a bespoke system or cheap rendering. We've got the quality of the first on the budget of the second."

Below-par building
After a fire destroyed fittings and finishings on Point West's upper floors three years ago, the 1960s-built block suffered a mass exodus of tenants. In a residential area with a surfeit of free office space, converting Point West to accommodation makes commercial sense.

Before the refurb got under way, the building looked horrible and performed badly. The steel frames of the ribbon windows running the length of each floor were rusting away and bits of the exposed concrete frame had broken off. And with single glazing, single-skin spandrel panels and extensive cold bridging (caused by the building's exposed concrete fins), Point West fell woefully short of modern standards on insulation and condensation for residential buildings.

For Miltiadou, Paroc cladding was an ideal solution. He'd been trying to implement the system on non-industrial buildings for years. "A friend from college had come across it and liked it, but thought the detailing was ugly. So he rang them up to tell them to do something about it. They did – hiring him as a consultant to oversee it. Now it looks great."

If you have a tower, make it beautiful

Socrates Miltiadou

Miltiadou's plans on previous projects to clad plant rooms with Paroc had always been cut out at the final stage in favour of blockwork, which is cheaper. But Paroc is considerably cheaper to install than other metal cladding because it was designed as an uncomplicated, high-volume system for factories and industrial units.

System saves cash
"There are loads of way to clad a building, but most are quite laborious," says Miltiadou. "You can have standard systems, but not very. Cladding is about specials, which take up 90% of your time for 10% of the design. Paroc costs around £100 per square metre; most other cladding starts at £250. The last job I did [City Point, the old BP headquarters], we spent £35m on the cladding – that's upwards of £500 a square metre."

Miltiadou designed the Point West refurb around the cladding, pushing the external walls out past the building's projecting concrete fins to create a completely flat expanse for the cladding. Steelwork attached to the concrete fins supports the panels around the building, and has allowed Miltiadou to push the floorplate out by 30cm to join up with it.

"It gives us more floorspace, protects the concrete frame, and makes the cladding installation more efficient," he says. "Paroc thrives on having a flat surface, as on steel industrial buildings, which have little undulation. Bays are expensive."

A 150mm-thick layer of mineral wool with sheet steel facings gives Paroc a U-value of 0.28. Pre-painted steel (silver on the outside, white on the inside, in the case of Point West) makes for a completely prefinished system: internal and external surfaces are complete but for the builder's clean as soon as the cladding goes up.

It’s going to be stunning

Socrates Miltiadou

"The internal prefinish saves a huge amount of time," says Miltiadou. It's also thermally effective: on a hot summer day, the panels remain cool to the touch.

The system is also highly flexible. If a panel goes completely, you can just jack it up, take it off and drop a new one in. Because Paroc is so lightweight (two workers can comfortably lift the 6m-wide, 1.2m-high panels used at Point West), it's self-supporting, which means you can cut holes for windows anywhere you like in the panel.

Fast (but not that fast)
To reduce the glare from the old building's long stretches of glazing, Miltiadou has clad the entire building (with the exception of the cores at either end, the newly enclosed ground floor, and the ribbon glazing on the top two storeys) and inserted windows in the panels. A cherrypicker holds the tilt and turn and trickle-vented window in place while a team inside the building snap on the four sides of the internal frame – a job that takes no more than an hour per window.

Once Paroc resolved the manufacturing problems that resulted in late delivery, the panels have gone up smartly, if not quite at the ultimately over-optimistic projection of nine storeys in six weeks. "Even if we had been using the simplest floor-to-ceiling glass cladding system, we couldn't have gone faster than one storey a week," says Miltiadou.

After five years trying to use Paroc on an office or residential building, Miltiadou is now recovering from the surprise of a client actually saying yes. "I can't wait to see it finished," he says. "It's going to be stunning."

Paroc on the inside

Unlike most other suppliers of mineral fibre-filled cladding panels, Paroc develops and manufactures its own insulation. “We put various stones in our mix,” says Paroc’s Robert Gray, “but it’s high in lime, which gives good durability and strength.” This inherent strength, combined with thicker steel facing for higher wind loads, allows installers to dispense with intermediate steelwork to support the panels, which can span unaided between the 6m centres typical of concrete and steel new-build. Gray says a key differentiator from foam insulation is that mineral wool is non-combustible and has a Class 0 fire rating. He also points out that the system is well proven, with Paroc having made the panels since 1982.

Not in my back yard!

Getting planning permission to convert Point West to a hostel for the homeless took one year, and was only granted on appeal against the wishes of local residents. Miltiadou says all the complaints came at the start of the project, and since work on site began there haven’t been any. “It’s a residential area,” he says. “It’s an appropriate use.” Client Metro Hotels, which also runs a large hostel in Southwark for refugees, will lease the units for an annual rent to local authorities looking for temporary housing for families and single people. Residential units will run up to the fifth floor. Storeys six and seven are for the hostel’s administrative staff, while the top two storeys are not owned by Metro Hotels and will be used as offices. Indeed, the upper two storeys will keep their ribbon glazing, although the spandrel panels below them will be clad with Paroc extending beyond the concrete fins as on all the other floors. Converting Point West will involve partitioning the floorspace into 40-odd residential units, all with their own kitchens and en-suite bathrooms. The units will include 10 for families and four on the ground floor (newly enclosed with the same blue engineering brick that covers the cores) for people with disabilities. Miltiadou expects to complete the fit-out by Christmas.

Source

Construction Manager