Tilt-Up takes off

October 21, 2015  3288  3288   

The tilt-up building method, though not new to South Africa, has huge advantages over conventional building methods – such that it ought to be applied more extensively than it has to date.

This is the view of the Durban-based Bedrock Group, which entered the field about 18 months ago. During that period it has landed and executed a range of large tilt-up contracts in Kwazulu-Natal and Gauteng. In addition, it provides a consultancy service to other contractors, consulting engineers, architects and others – including end-users – wishing to adopt the system.

"We are on a mission to promote its wider use. For this reason we don't see other contractors as competitors but as potential collaborators. As a contractor we couldn't possibly handle all the work that's in the offing, apart from which we have the expertise that enables us to provide a consultancy service to assist others to get involved," commented David Kitching, Bedrock's General Manager.

"The primary focus of our approach is to promote the use of tilt-up technology as an alternative to conventional building techniques."

Acceptance has been won so far among a range of companies that include some well-known commercial and industrial companies. "However the vast majority of potential users, along with contractors and specifiers, still have to be won over. There's still huge potential for growth in the application of this technology," Kitching stressed.

What is tilt-up?

Kitching's business partners are his brother Greg Kitching and Chris James, who both worked previously with another company specialising in tilt-up construction, as well as both having many years of prior rigging experience, which plays a crucial role in tilt-up technology.

So what is tilt-up? It comprises the use of precast concrete elements in place of conventional on-site casting of concrete columns and beams and bricks-and-mortar walls. But it also differs significantly from the normal use of precast components in that all the precast elements used are cast on site – but not in-situ.

"The precast elements are all cast on site on specially prepared casting beds that are within radius – that is, within reach of the crane that is used to lift them and place them in the building under construction. The precast elements have special lifting inserts cast into them for the purpose of lifting," Kitching explained.

"The trick in tilt-up is in the planning and lifting. This is where we come into our own because we have the experience needed to perform these tasks most effectively, plus all the equipment that goes with it."

Advantages

Tilt-up has been is use internationally for many years – especially in the United States where it was first developed and applied.

"The principle advantage is that there are enormous cost savings compared with conventional construction methods. It also greatly speeds up the construction process, as the components involved can be cast and be ready for installation well ahead of time," Kitching stated.

"In addition, the installation process itself is very speedy. For example, a precast column is lifted and placed in one go, whereas conventional in-situ casting is a laborious and time-consuming process involving erecting and re-erecting of scaffolding and formwork and several successive pourings of concrete by means of a bucket and crane. The building of walls by conventional methods using bricks or blocks and mortar is similarly unwieldy by comparison with tilt-up."

While tilt-up may be applied in the construction of multi-level multi-roofed buildings, it is best suited to "big box" buildings – typically warehouses, distribution centres, factories, shopping centres and other retail stores of the big box type. The majority of the tilt-up contracts Bedrock has executed to date have been for warehouses and large retail outlets.

The system has gained some ground winning acceptance in the market place in recent years, but it has a long way to go to realise its full potential. "Columns have been more readily accepted so far than wall panels, the reason being that since you would be building columns using concrete anyway when applying the conventional solution, the advantage of a complete precast column seems more obvious – and less revolutionary! – than replacing bricks-and-motor walls with precast wall panels," Kitching commented.

Structural support

"The logical next step beyond this is for the use of precast wall panels for structural support purposes, as opposed to filling in the gaps between a series of columns," he added.

"In the case of warehouse and factory buildings, columns used in this way are less of a problem than they are in retail buildings where they tend to limit useable space and are also aesthetically unappealing. In addition, walls uninterrupted by columns offer more scope for accommodating windows, doors and other features. Consequently in shopping centres uninterrupted peripheral walls are preferred and therefore also serve a structural support function.

Said Kitching: "In addition to the cost- and time-saving advantages of tilt-up already mentioned, much greater accuracy can be achieved making window and door openings in wall panels produced by this method than when building brick-and-mortar walls."

He emphasised that the best route to go to ensure that all the advantages of tilt-up are capitalised on is to "get in at the ground floor" by having it incorporated right at the start when the proposed building is still being planned. "That's why we are doing our best to gain its acceptance by architects and consulting engineers. Ideally we should already be part of the team right at the start when the building is being designed, so that we can sit with the architect and consulting engineer and co-ordinate all the tilt-up elements in their plans, rather than bringing it in as an add-on later.

"At the same time we offer our expertise to other contractors to help accelerate the acceptance of tilt-up in the industry."

Bedrock's tilt-up business, incorporating both handling turnkey contracts directly as a contractor and consultancy work, including assisting other contractors by providing expertise and a range of hardware, accounts for about 65% of its total turnover, while contracts for customised precast concrete products contribute the balance.