The information on this site is a good source of the
broader information on quality materials and workmanship, with explanation. The
Deck Master Decking Materials Advisory is a
good source of information and starting point for discussing your requirements
for materials with your supplier.
The
Deck Master Construction Standard is a good
source of information and starting point for discussing your requirements for
materials and construction with your
Deck Master.
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
-
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
-
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.