We have had a very mild autumn with many pleasant days. Unfortunately life in Christchurch continues to be trying due to the earthquakes and aftershocks. Since I last wrote a number of issues have arisen as a result of the
extensive damage to many Christchurch residential and commercial buildings. For example a new building standard NZS 3604 2011 has come into force which more than doubles the bracing requirements for new buildings and those being repaired or strengthened.
This code was developed partly in response to the September earthquake. However since the February earthquake the Christchurch City Council now require a bracing ratio equivalent to that of Wellington. The result is a ratio increase from 13 to 33.This requirement will have a considerable impact on the design of buildings to allow for this increase in stiffening to be implemented. One of the effects will be on the choice of both roof and exterior
claddings particularly in relation to heavy weight options such as concrete tiles for roofing and bricks and stone veneer for wall cladding. These types of claddings will need more internal and external walls suitable to act in support. This in turn will affect the amount and size of internal open plan spaces because the wall ratio relative to the size of the open spaces or opening in the walls for windows is now required to be much higher. The challenge for those of us in the design process is balancing the need for open plan living with the requirement for more walls.
Alternatively choosing a lighter weight exterior cladding is an option or using more mass construction such as tilt slab or filled concrete block.
Other changes you may be more aware of relate to foundation design. For example, where liquefaction is more likely, concrete slabs will need to be a lot thicker and extensively reinforced. Driven piles may also be required. If you would like further clarification on any of these issues I would be happy to discuss them further.
I have appreciated assisting and being of service to those of you dealing with earthquake damaged buildings and the subsequent rebuild/repair process.
With the winter months upon us and in circumstances which for many of us is less than ideal our challenge will be to draw upon the creativity, innovation and warm heartedness that we all have within.
All the best