Best house inspection articles


How To Choose The Right Wood For Your Deck - Durability Factors

Perhaps the most important consideration inincluding Teak, Jarrah, Jatoba, Bongossi,
choosing the lumber species to use forPurpleheart, Selangan batu, Western Red
exterior decking is the durabilityCedar, Merbau, Blackbutt, Spotted Gum, River
characteristics of the lumber to be used.Red  Gum  etc.
Unfortunately this is not a precise science
as wood is a natural species, withThe third group, Class 3 is termed
significant variations even within the same"Moderately Durable". Such species will give
species. For example a species grown in onegood service without preservative treatment
country may have significantly differentif clear of the ground and used in conditions
durability characteristics to the sameof low termite hazard and involving only
species grown in another country. This may beintermittent wetting followed by reasonably
due to more rapid growth, harvesting at anrapid drying. Such timbers can still be used
earlier age or to a lesser extent,for exterior decks but it would probably not
differences in processing. Furthermore,be advisable to use such species in severe
similar species may have sub-species whichweather conditions unless a maintenance
could exhibit totally different durabilityregime involving the application of good
characteristics.quality decking oil is carried out at regular
intervals. Species in this group include
Due care should be taken that any wood doesCambara,  Kempas,  Karri, Eucalyptus saligna.
not contain the outside sapwood. Sapwood of
most hardwood species is non durable and willThe final group Class 4 is termed "Non
decay quite rapidly even if the heartwoodDurable". Timber species in this group are
itself is rated as highly durable. With someconsidered unsuitable for exposed decking
cypress species in particular, the sapwood isbecause  of  their  low  natural  durability.
prone to decay extremely quickly. Fortunately
sapwood is generally a lighter color, so canBut apart from resistance to the ravages of
be  reasonably  easily  distinguished.sunlight, rainfall and humidity, in many
locations there is another factor to consider
To a large extent, the denser, harder lumber- termites. There is no direct correlation
species generally possess higher durabilitybetween durability and resistance to termite
properties. These are often referred to asattack so care needs to be taken in termite
Class 1 or "Highly durable". Examples of suchprone areas. Suitable species with high
species includes Ipe, Cumaru, Tallowwood andresistance to termite attack would include
Ironbark. Under normal conditions, not inIpe, Cumaru, Jatoba, Teak, Jarrah, Selangan
permanent contact with water, such speciesbatu  etc.
can be expected to resist decay and insect
attack for at least 25 years and up to 50Finally and perhaps of lesser importance is
years.that the lumber chosen should not twist, cup
or deform in service. This requires some
The next group is Class 2 where the lumberskill and experience on the part of the
species are termed "Durable". Lumber specieslumber mill as the majority of hardwoods
included in this group also exhibitrequire carefully controlled kiln drying to
exceptional durability characteristics andbring the moisture content of the wood down
the wood can typically be expected to havefrom more than 25% with freshly cut timber to
life of 15 to 25 years or more. Some speciesapproximately 16%. If the timber is dried to
in this group closely approach thefast it can crack and twist when in service.
performance of the Class 1 timbers even underEven when properly kiln dried, all timber
severe conditions of service and in fact allwill expand and contract to some extent in
species in this group may be regarded asservice particularly in damp conditions. In
approximating the service of Class 1 timberssuch conditions, a timber species with a low
where conditions are less severe, as inshrinkage rate may be preferable. Such
typical  decking.species would include Ipe, Selangan batu,
Merbau and Teak amongst others.
This group includes a large range of species



1 A B C D 57 58 59 60 61 62 63 64 65 66 67 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106