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When considering the trade-off between price and quality, two sayings
are relevant - "You only get what you pay for" and an expression used in
an old Castrol Oil advertisement "Oils aint oils". The first
is self-explanatory whereas the second is intended to indicate that "not
all oils are equal" or not all oils provide the same protection to an
engine.
In the same way we can say that not all generically named decking
products and construction techniques are equal ie:
-
not all subframe timbers are equal
-
not all decking timbers are equal
-
not all fixing materials are equal
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not all construction methods are equal
-
not all decking fixing methods are equal
and so on.
As a broad generalisation, higher quality
materials and construction techniques will perform better and last
longer. Generally, each improvement in quality is associated with
an increase in cost, however, some increases in cost may be
disproportionate to the quality increase - refer to Decking below.
Examples
In subframe timber and decking, good quality will cost a reasonable
amount more than poor quality, however the performance improvement
between the worst and best is significant. The performance and cost
difference between "good" and "better" may not be as great.
Subframing - unseasoned Queensland Black Butt is a significantly better
performing timber than unseasoned New England Black Butt (NEBB) - unseasoned NEBB should not be used due to its high shrinkage. Unseasoned
Spotted Gum is a better performing timber than unseasoned Black Butt but
the difference in performance is not as great. Unseasoned Iron
Bark is possibly a better performing timber than unseasoned Spotted Gum
but the improvement would not be noticeable or needed by the majority of
users - an exception is noted below.
Decking - Merbau/Kwila is a significantly better performing timber than
Belau in weather exposed conditions. The higher quality Australian hardwoods are probably better
performing timbers than Merbau/Kwila however the difference in
performance is not as great. The price difference between higher quality Australian hardwoods
and good quality
imported timber such as Merbau/Kwila, and which is more expensive at any
time, will vary
depending on supply and demand conditions and resultant pricing in the Australian and
international markets. The price difference will also depend on
the appearance quality required with Select (Appearance) Grade (if
available) being more expensive that Standard Grade.
Our recommendation is always to choose your
subframe and decking timbers from the starting point of required
performance for your conditions with a reputable timber supplier able to
assist you to make an informed choice for your needs.
Fixings - Domed head stainless steel
twist shank gun nails (50x2.5mm for hardwood joists) are a significantly
better product than T-nails for fixing decking - T-nails should not be
used due to its thin straight shank and inadequate coating for external
conditions. Hand nailing with domed head stainless steel twist shank nails
(50x2.8mm for hardwood joists) is better
than gun nailing however the performance improvement may not be as
great. We say "may not" as different gun nail brands exert
differing hold down forces and gun nails have not been used for a
sufficient period to know if they perform well over the long term.
Our recommendation for hand nailing will cost a reasonable
amount more than gun-nailing with stainless steel domed head nails
however initial hold down is better and there is experience of good
performance in the longer term.
Fixing Techniques -
Some quality practices such as nailing in a staggered alignment to avoid
splitting the joist and using Malthoid as a joist sealer will make a
significant improvement to performance and/or longevity for
marginal additional cost - staggered nailing should only be
marginally more expensive, if at all.
Note on careful specification of requirements
In relation to subframe timbers, specifying according to strength
rating eg
"F14 hardwood" is too general as a large number of hardwood species can
be supplied to F14, many of which have characteristics such as high
shrinkage or low durability which are not suitable
for decking subframe timbers.
The lowest cost F14 may also be the lowest quality.
However, if you have discuss your requirements with your timber merchant
and agree on a standard for supply eg F14 unseasoned structural grade
Spotted Gum you have specified both a good quality timber and have
also ensured that when you get some quotes "all subframes timbers will
be equal" or at least very similar.
In relation to decking, specifying "hardwood decking" is too general and
would allow many species which are not appropriate for exposed
conditions. If decking is to be installed in
conditions protected from sun and rain, such as under roof, or in
moderate conditions (cooler climate with low rainfall) lesser quality
decking may perform to an acceptable standard.
Note: In some markets, the supply of
unseasoned decking is common. We would recommend against the use
of unseasoned decking, as the decking will season in place leading to
stresses on the fasteners an uneven gapping between the boards. We
recommend that you specify "seasoned decking" of a specific high
durability and stability species.
In relation to fixings, specifying
"fixing with two nails at each joist" is too
general as it does not specify which specific fixing to use and would
allow nailing in line which is not a good practice as it can split the
joist leading to fixings working out and accelerated deterioration of
the joist.
You can also be selective in what quality requirement you specify to
keep the cost to a minimum for good quality materials and workmanship eg
high durabilty and low shrinkage hardwood subframe timbers will in
the majority of cases provide good performance and longevity.
Specifying that same timber as "seasoned" or specifying "Iron Bark"
may
add a significant cost for not much additional benefit - in the
majority of cases.
In some cases, it may be worthwhile to specify the highest
quality eg
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if a deck butts up against a concrete pathway you may consider it
worthwhile to pay the extra for seasoned subframe timber (remembering that high
durability is still required) to avoid the level of the deck becoming
lower as the subframe shrinks and
-
is a deck is to be exposed to the weather in a high rainfall and high
temperature application eg in tropical North Queensland, specifying Iron
Bark may be reasonable to ensure long-term performance.
Conclusion
Good quality will cost more than lesser quality,
however we recommend using only good quality materials and workmanship
to ensure that you gain the satisfaction which comes from a deck which
performs well over a long life.
Good quality is not automatic. There is a
wide range of qualities in materials and workmanship supplied in the
decking market from lowest (and possibly unacceptable) to best. If
you do not specify good quality you may not receive it
Do not leave supply of good quality materials and
workmanship to chance.
Our suggestion is that you determine the quality of
materials and workmanship which is appropriate for your personal circumstances,
application and geographical location, specify your requirements carefully,
possibly after discussions with your materials supplier and Deck Master and make sure you get what
you have been quoted on.
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