D&C benefits for early adopters

Design & construct contracts are becoming more important as time and cost pressures increase. Northrop Consulting Engineers principal Jamie Shelton outlines how savvy construction contractors and developers can reap the benefits of D&C by the early adoption of engineering expertise.

Northrop is seeing strong demand from both clients and builders for design & construct (D&C) contracts. For clients it offers benefits in risk shifting, project funding, and speed in progressing from approval to construction. Builders like D&C as it provides greater control over aspects of the design that affect how the building is constructed and, ultimately, this greater control should improve their bottom line.

Planning regimes in Australia's major capitals are only getting slower - extended approval times create uncertainty, delay building commencements and put pressure on contractors and engineers to deliver construction in shorter and shorter timeframes.

Construction methodology is a balance between cost and speed, and D&C empowers the builder to choose the quickest, most cost-effective way to build. You know you’ve got it right when the fastest way to build is also the cheapest.

As the construction market heats up we are seeing increasing competition for trades and rising costs of building materials. D&C builders manage this risk by selecting a construction process which enables them to quickly and confidently deliver the product.

The earlier builders and engineers get together on a project, the better the outcome – working through ideas and appraising their merit against cost, logistics, reliability of supply, fitness for purpose and, of course, speed.

On D&C projects an important part of the engineer's role is to integrate the elements of various specialist sub-contractors into a coordinated building, that captures the time and costs benefits without compromising the client’s project objectives.

However, for all the advantages of design & construct methods, there are still some engineering challenges involved in applying D&C to building construction projects, and they revolve around the afore-mentioned critical issue of speed and its impact on cost.

Building services engineers, in particular, have a challenging role within D&C construction. Clients and architects absolutely need their involvement during design development, however builders tend to proceed through detailed design and construction without them. This can lead to the design intent being compromised by cost and program, which is a risk associated with the D&C process. Although building services engineers provide value in a post-tender advisory and review role, the increasing use of BIM modelling means their earlier involvement in MEP design greatly increases their value, and flow-through benefits follow.

There are other factors influencing D&C contracting, and engineers are working with builders to increase the speed of construction, including the application of new construction techniques, incorporating advances in plant and advanced materials.

A good example of a new construction technique working well within the D&C space is jointless fibre slabs for industrial and logistics facilities. These slabs are not just quicker to build, they provide a better finished product than conventional jointed slabs and a higher degree of crack control.

Offsite manufacture of components and building elements improves certainty around cost and program timeframes, and provides a product of consistent quality. Most construction processes are a ‘one-off’ – they each have unique logistical challenges which require engineers and builders to draw on an extensive arsenal of solutions. However, clever builders and engineers understand how a complex ‘one-off’ construction project can incorporate repetitive elements that are well suited to offsite manufacturing.

Examples of offsite components include metal decking replacing formwork and the use of pre-cast concrete walls and columns. Manufactured elements include modular bathrooms, airconditioning plant fully assembled on platforms, and curtain walls with integrated shading.

Even with current technology, the future of property development and construction is already trending towards the wider adoption design & construct contracts, and this is while modular / prefabricated techniques and 3D printing are in their infancy. But these are topics deserving of their own column.

Right now, however, smart developers and construction contractors can reap the benefits of D&C by involving engineers early in the process. Just as in business, early adopters tend to win.

Principal | Senior Structural Engineer
Jamie Shelton

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