TECHNICAL
Engineering of Residential Buildings
Understanding this area is essential for the building of structures that are sound and ‘fit for
purpose’. There is more to this than the building simply staying up and there are many
factors to consider. So what does the Building code of Australia have to say…
A building or structure, during construction and use must:
 perform adequately under all reasonably expected design actions
 withstand extreme or frequently repeated design actions
 be designed to sustain local damage, with the structural system as a whole
remaining stable and not being damaged to an extent disproportionate to the
original local damage
 avoid causing damage to other properties
 resist the actions to which it may reasonably be expected to be subjected.
These actions can include:
 permanent actions (dead loads)
 imposed actions (live loads arising from occupancy and use)
 wind action
 earthquake action
 snow action
 liquid pressure action
 ground water action
 rainwater action (including ponding action)
 earth pressure action
 differential movement
 time dependent effects (including creep and shrinkage)
 thermal effects
 ground movement caused by—
 swelling, shrinkage or freezing of the subsoil
 landslip or subsidence
 siteworks associated with the building or structure
 construction activity actions
 termite actions
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Q How do I construct a building to resist all these actions with a deemed –to –satisfy
approach.
A The designer of a building will use the expertise of engineers in the interpretation and
application of Australian Standards referenced by the BCA to meet these performance
requirements.
Q What are main Standards and which type of engineers are relevant.
A The following areas are covered by:
Structural Engineers – These engineers are skilled in the ability to make calculations to
determine structural performance in the following areas:
AS/NZS 1170 Structural design actions – wind, snow, ice and earth quake
AS 1684 Residential timber-framed construction
AS 1720 Timber structures
AS/NZS 1664 Aluminium structures
AS 2159 Piling — Design and installation
AS 3600 2009 Concrete structures
AS 2870 2011 Residential slabs and footings
AS 4055 2006 Wind loads for housing
AS 4100 1998 Steel structures
NASH Standard Residential and low-rise steel framing
Geotechnical Engineers – These engineers are skilled in the determination of all aspects
of the earth and how it relates to structures especially with regard to footings.
AS 2159 Piling — Design and installation
AS 2870 2011 Residential slabs and footings
Hydraulic Engineers – These engineers are skilled in calculating how drainage systems
will perform and establishing the design and product options.
AS/NZS 3500 Plumbing and drainage
Q How do I construct a building to resist all these actions on a performance based
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approach.
A An engineer will make calculations that can be verified to meet the performance
requirements of the BCA. This may be a more costly approach, however it can lead to
more innovative design and construction solutions.
Q What does a Principal Certifying Authority (PCA), appointed to make sure development
work is completed under the terms of any Development Consent or Complying
Development Certificate and the Building Code of Australia, require in terms of
structural engineering compliance. Council or an accredited Private Certifier can act as
the Principal Certifying Authority.
A Most Councils have on their website an Engineering Specification that can refer to an
Engineering Plan plus a typical set of Standard Drawings. Together these tell you what
documents are required by a PCA to confirm the adequacy of the structural design.
Q What qualifications for Engineers that certify plans and specifications are required by a
PCA?
A Members of Engineers Australia that are Chartered Professional Engineers (CPEng)
and on the National Professional Engineers Register (NPER) are appropriately qualified
engineers. Verification that the person you are engaging is a current CPEng and/or is
currently registered on the NPER can be checked by either viewing their current
membership card or certificates.
Q What is the process by which the work of engineers is certified?
A Engineers ‘sign off’ that the calculations done for structural design of framing, steel
work, footings, storm water and drainage is to the ‘Code’, meaning the BCA and
Australian Standards. Where the building regulations allow and the risks are small,
structural engineers can certify their own designs.
For large projects where the risks are greater, structural engineers have their designs
checked by an independent engineer. Costs for independent checking may be
additional to the design engineer’s fee.
Q Why should I use the services of a structural engineer for simple calculations such as
beam spans for a roof structure?
A The engineering certificate that an engineer provides confirms the adequacy of the
design and this can be provided to other parties for certification. Should a failure occur
then responsibility lies with the engineer.