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Quality in materials and
construction are the most important aspects of decking delivery
as these elements determine whether a deck will perform well over
a long life when exposed to the damaging effects of weathering.
The Building Code of Australia (BCA) contains
technical provisions for the design and construction of buildings and
other structures, covering such matters as structure, fire resistance,
access and egress, services and equipment, and certain aspects of health
and amenity. The BCA has the status of building regulations in all
States and Territories, providing the minimum regulatory requirements
for buildings in Australia. Your decking project must, as a minimum, comply with
the BCA. In addition to the requirements of the BCA there are many
good practices in material selection and construction techniques which
are appropriate to deliver a satisfying decking project which gives good
performance over a long life.
Following are the important individual elements in the
construction of a deck. Although we believe that these elements combine
the best practices from the BCA and from experience in decking materials
and construction, if there is any discrepancy between these
elements and the requirements of the BCA, the BCA shall take precedence.
Similarly, if any element is not addressed eg termite management or
handrail design and construction the requirements of the BCA shall be
complied with.
In addition to the requirements of the BCA, it is
strongly recommended that the deck builder, specialist contractor or
customer (as appropriate) apply the following good practices:
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Use good workmanship
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Use good quality subframe timber (low shrinkage or seasoned and
of high durability) of the strength group specified in the design
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Use wide joists - 50mm unseasoned, 45mm seasoned
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Use good quality decking timber (seasoned, stable and of high durability)
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Use hot-dipped galvanised or stainless steel
fixings as required by the BCA and suitable for the exposure conditions.
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In
highly corrosive environments such as in coastal areas and
around pools, all post supports, brackets and fixings (including nails,
bolts, concrete anchors, screws and
connector nails), shall be stainless steel.
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Protect decking from heat and moisture while
stored on site prior to use
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Provide suitable drainage and grading of the area under the deck, to ensure
water runs away freely and the area under the deck dries quickly after rain, without water pooling
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Seal cut ends, checked joints and timber
interfaces.
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Apply a finish/sealer liberally to the cut
ends before fixing decking
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Allow a 3 to 5mm gap between adjacent boards
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Stagger butt joints so they do not occur on adjacent boards
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Fix decking by hand or machine nailing with stainless steel or hot
dipped galvanised twist shank domed head nails - galvanised bullet
heads can be effective into hardwood joists
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Hand nailing will give a stronger hold down than
machine nailing but takes longer and will be a more expensive option
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For machine nailing use a nail with a coarser pitch (threads further
apart) to allow the nail to screw in when subjected to high driving
force from a nail gun)
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Place nails in a formal staggered alignment to
avoid splitting the joist
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Drill a small pilot hole in the decking to avoid
splitting
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Drill the board ends and hand nail to avoid end splits
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Drive nails so that the head is flush with the
top of the decking - do not punch
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Apply another finish coat after the decking has
been laid (where a penetrating oil or stain finish is to be used) or
as recommended by the manufacturer
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Reapply the decking finish at regular intervals as recommended by the
finish manufacturer
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Undertake a termite inspection at regular
intervals as recommended by pest treatment professionals in your state
To achieve best long term performance, the
following practices should also be undertaken:
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Cut deck board butt ends with a slight backward undercut
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Seal the tops of joists before fixing decking
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Apply one sealer coat all round the decking
boards before fixing (where a penetrating oil or stain finish is to be
used) or as recommended by the manufacturer, to protect
decking from weathering
Although the good practices above are detailed, there
are few additional activities required to build a good deck than to
build a poor deck. It is simply a matter of
using the right materials and practices in each situation.
The
recommended construction practices are outlined in greater detail in
the following documents available as downloadable copies:
Please
note that the recommendations contained in the Construction Standard are not
mandatory or automatically applied in their entirety by your local Deck
Master who may have access to suitable alternative materials and may have developed alternative techniques which have been found to be effective and efficient.
It is suggested that you gain an overall understanding of the materials
and construction issues from the Construction Standard and then discuss
your requirements for your project with your local Deck Master, with
reference to the Construction Standard, and if you require or prefer that specific materials or techniques be incorporated into your project
eg hand nailing for improved and longer lasting fixing, that you discuss your requirements with your local Deck Master and come to a suitable agreement.
Deck Master Construction Standard - (click
here for a downloadable copy),
with additional explanation in the
Deck Master Construction Standard Explanatory
Notes
(click
here for a downloadable copy).
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