Making the Most of Your Existing Structure

At the recent Green Build Conference, the world’s largest conference dedicated to green building, it was reported that 42 per cent of construction work in Australia over the next three years will consist of refurbishment and retrofitting work.

As more and more clients are finding that money is getting tighter, improving and adding value to existing assets is becoming a preferred choice instead of undertaking a new build.

Buildings from the 1960s and 1970’ have traditionally been constructed solidly, but building codes from back then differ hugely from those of today.

So what are some of the challenges and solutions to get the most out of your refurbishment project?

When working within the physical constraints of an existing building, the need for new services is a common and sometimes expensive reality.

The challenge is mitigating the expense. The starting point for any design must be the existing infrastructure, with building owners tasked with working out how best to utilise it and minimise the need for additional structural members.

Existing concrete slabs on ground are typically trenched and new services are laid underneath before the slabs are re-instated. As an alternative, we try and use existing structural frame to channel/support services – such as cables – down and within steel columns and through existing roof members. In addition, the strengthening of existing structural elements is sometimes required to achieve greater spans and/or heavier loads.

Upgrading or incorporating wet areas is another challenge, particularly when providing set downs in existing concrete slabs. Although potentially challenging, the best and most cost efficient solution is to remove and re-instate the concrete slabs without cutting existing reinforcement bars in the footing beams whilst ensuring the structural integrity of the footing system.

Improving or providing disabled access is now fundamental to any upgrade project. Difficulties here come as a result of existing building constraints, whether due to the footprint or services, which simply did not give consideration to such requirements. Balancing the need for buildable solutions while minimising cost and ensuring the structural integrity of existing building is the primary goal and close collaboration with the architect and/or interior designer is crucial.

Any substantial renovations on buildings constructed prior to 1979 are required to be assessed for performance under earthquake loading. The challenge here is in incorporating new structural connection details while minimising the visual impact. This is also the case with bracing the existing structure against wind loads. If alterations reduce bracing capacity or increase bracing requirement, then the structure must be analysed and subsequent retrofit work may be required.

There is also a need to future-proof spaces. There is no sense in designing a solution for today only to end up with the same problems in another 20 years. We may not be able to predict exactly what may happen in the future but there are still ways to increase the longevity of use and enable diversity and flexibility in a building. For example, look to limit the number of physical (non-movable) intrusions (obstacles) in a building space.

 

The refurbishment of Morphett Vale High School in Adelaide is a good example of what can be achieved on a challenging budget where a new build just is not viable.

The upgrading of local amenities is essential, and the redevelopment of this public school is one of just a few significant developments for residents in a long time.

The existing Morphett Vale High School comprised a combination of six purpose-built one and two-storey masonry buildings constructed in 1974. Most of the buildings contained asbestos both internally and externally.

The key components of the redevelopment have been to provide 16 general learning areas, three service learning areas with associated withdrawal spaces, practical activity areas, teacher preparation areas, storage and toilet facilities; to provide a new preschool in an existing steel framed masonry constructed building; and to provide a resource centre, science laboratory, canteen and new planning outdoor play areas.

By stripping the non-structural members (secondary framing, fixtures, and so on) of many of the buildings and leaving the skeleton, we were able to use the existing framing to support new framing requirements ultimately keeping costs down and significantly condense the construction phase. This was essential with a construction budget of less that $10m and a programme which had to consider the impact on the operations of the school.

As the market looks likely to remain cautious during 2013, the value of refurbishment projects to the whole construction industry is sure to increase.

Monday,
November 26, 2012
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Sarfaraz

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