Once put forward as a panacea for so many ills in the construction industry, the future for modern methods of construction (MMC), particularly in the plaster and drywall sector, remains unclear. Steve Menary reports
Prefabrication is at the heart of MMC. Mass-producing sections off site can have a number of key benefits for clients, says John O‘Connell, managing director of drywall specialist O’Connell’s.
He adds: “Speed of build has a great saving and time is money. The cost of materials overall is cheaper and the speed in method makes savings anyway. It’s also possible to achieve higher sound and thermal requirements which are vital to reduce carbon usage [and] most if not all materials can be recycled in the future should the building be damaged or replaced.”
Andrew Orriss, head of business development for SIG Insulations, said: “If we’re talking about methods like off-site assembly, the fragile nature and weight of plasterboard can sometimes be disadvantageous. Manufacturers are now preferring to move to cement board or magnesium oxide board, both of which are more durable and more weather resistant.
“In truth, the term MMC no longer has any real value. There comes a point where ‘modern methods’ become mainstream and with innovation in the construction sector very vibrant, the term MMC is now deemed by many to be defunct.”
There are examples of drywall being used successfully within an MMC solution, such as the £450 million Southmead Hospital scheme in Bristol. This scheme featured shower and toilet cubicles manufactured off site as pods and installed after drywall went up.
“These boards were installed before the envelope of the building was on and before the pods so they had to withstand being left in sometimes rainy conditions,” says Chris Williams from specialist contractor BR Hodgson, which worked with Siniat – previously Lafarge Plasterboard – on the project and installed GTEC Aqua Board.
This approach was specified by architects BDP for programming reasons. Chris Norris, senior technical specification manager at Siniat, explains: “There was a requirement for a fire and sound insulated compartment partition between the back-to-back configuration.
“The pods needed to be installed into the building and positioned ahead of the external wall envelope being installed for access reasons. Traditional drywall systems could not have been used as this was not a water-tight environment.
“We’re seeing more and more major projects being delivered through modular construction, particularly on schemes where there is a high degree of repetition. Pre-fabricated offers main contractors better control over build programmes and the phasing of sub-contractor interfaces.”
John Butler at London Drywall says more and more off-site assembly is happening: “Demand is driven by many issues, such as speed of construction or the need for self supporting structures. Where there is restricted access sections of light gauge steel frame can be manufactured then delivered to site in an agreed sequence and assembled.
“Manufactured wall frames have also become popular and were used very effectively last year when we installed retail concession buildings for use during the Olympics. The concept is not only faster once on site; there are also safety advantages.
“When faced with long runs of glazed partitions we’ve manufactured flying bulkheads off site.”
Manufacturing units in a controlled environment means that prototypes can be tested heavily before being brought to site, but the use of drywall does not always sit with the principle of MMC.
Steve Halcrow, technical consultant to the Federation of Plastering and Drywall Contractors, says: “It makes sense to me that we should look to manufacture certain parts of it as pre-assembled units either in a factory off site or by setting up a manufacturing unit close to the workface.
“[But] drylining doesn’t seem to lend itself readily to a lot of the principles and tenets of a typically MMC approach. Prefabrication of units such as panels is all possible but fraught with difficulties.”
At Southmead, 110,000 sheets of plasterboard were used on 38 kilometres of walls. Here the MMC was as much in the toilet pods as the use of the board. To have board at the heart of MMC means that storage is potentially a significant issue; prefabricated drywall sections tend to be bulky and heavy and need significant space if manufactured in bulk.
John O’Connell argues that this offers greater opportunities for specialist contractors to achieve ‘approved & recommended installer’ status. This would surely only increase the already large responsibility that falls on all specialist contractors as main contractors look to pass risk down the supply chain.
James Cunningham, managing director of C&G Plastering, says: “The responsibility often falls upon the installer who has to be aware of every requirement for the site and ensure that the product installed is fit for purpose and within budget.
“I think main contractors would like to use MMC but their budget values do not allow for improved methods, as material choices are often more expensive. The client will always determine the products to be used, planners and architects will also have a say and the main contractor will try and encompass a build which makes them the most margin.
“It is this depth of issues which has caused the whole procurement process within our industry to be drawn out: too many cooks want to insert ingredients, but not many want to be accountable to taste it.”
Steve Halcrow of FPDC agrees that main contractors need to be able to embrace MMC better when it comes to drywall.
He says: “It makes sense to me that we should look to manufacture certain parts of it as pre-assembled units either in a factory off-site or by setting up a manufacturing unit close to the workface.
“In my view, to accommodate any meaningful amount of innovation in the way of pre-fabrication of panels or parts thereof requires principle contractors to think significantly differently about the way they program and coordinate the works of the various trades. They appear reluctant to do this, or perhaps unable to comprehend what is needed.
“Despite much hand-wringing, no-one seems to have the required time or resource to invest in changing the way we do things, and therefore the way we think about drywall. The real sticking point seems to be the mind-set of the people in charge of the projects.”