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Timber Preservation
Treatments -
Managing timber durability
Jack Norton
Wood products in Australia have to perform over a huge geographic
range and comparing our specifications with those in other countries
is ??????
Australia uses a lot of (treated) wood products in domestic house
construction.
Euc. Tereticornis siding (Forest red gum)
Corymbia maculata posts(Spotted gum)
LOSP treated radiata pine
CCA treated slash pine lattice
Intsia bijuga stair rails(Merbau)
Toona calantas doors(New Guinea cedar)
Australia uses a lot of (treated) wood products in domestic house
construction
LOSP treated radiata pineLOSP treated radiata pine
Intsia bijuga (Merbau) stair treads & rails
CCA treated slash pine battens
What IS NOT included in “wood preservation” in Australia?
chemicals
weathering
Fools
fire
<<<<<
What IS included in “wood preservation” in Australia?
decay/rot Insects
termitesmarine borers
This presentation addresses hazards we can control
Controlling the hazards
Hazard Decay Insects Termites
Design & detailing
Natural durability
Preservative treatment
✓ ✓
✓
✓
✓ ✓
✓ ✓
Zones in a tree Hardwood/eucalypt
sapwood
heartwood
Conifer/pine
Natural Durability classifications - decay
40>25>1
15- 4015 – 252
7 – 155 – 153
Up to 7Up to 54
Above ground
(years)In-ground (years)Durability class
A species is classified as resistant or non-resistant to termite attack
A species is classified as resistant or non-resistant to insect attack
Durability information is listed in AS 5604-2005
heartwood
Natural durability classification systems - compared
Class 1 2 3 4 5
Probable life in years
Aus A’Gnd ➢40 15 to 40 7 to 15 0 to 7
Aus I’Gnd ➢25 15 to 25 5 to 15 0 to 5
EU ➢5 3 to 5 2 to 3 1.2 to 2 < 1.2
China ➢9 6 to 8 2 to 5 < 2
Japan ➢9 7 to 8.5 5 to 6.5 3 to 4.5 < 2.5
Malaysia ➢10 5 to 10 2 to 5 < 2
Bangladesh ➢3 2 to 3 1 to 2 < 1
Tanzania ➢10 5 to 10 2 to 5 1 to 2 < 1
Brazil ➢8 5 to 8 2 to 5 < 2
USA ????????
Preservative treatment – Can’t protect all the wood
Sapwood
heartwood
Where is wood likely to be used – Hazard class system
MarineH6
Ground contact – criticalH5
Ground contactH4
Outside above ground - decayH3
Inside - termitesH2
Inside – insectsH1
ExposureHazard
Class
Treatment required
• Each hazard class has a set of specifications involving active ingredient,
species (natural durability), retention and required penetration.
Preservative[nominated preservative element or
compound for expressing retention]
Minimum retention in the defined Zone Required to be Penetrated of a
nominated preservative element or compound in treated timber
CCA preservatives[% total active element (%Cu+%Cr+%As)]
conifer and hardwood
0.380%
ACQ2100 [% total actives (%Cu + %didecyl-dimethylammonium chloride [DDAC])
conifer 0.350%
hardwood 0.390%
Tanalith E [% total actives (%Cu + % tebuconazole)]
conifer and hardwood
0.2290%
Link between natural durability and penetration required
Product Zone Required to be Penetrated
H levels involved
Sawn and
round timber
Heartwood Durability Class
Class 1 Class 2 Class 3 Class 4
All sapwoodH1
All Lyctine beetle susceptible wood
All sapwood
All sapwood and not less than 5 mm from any heartwood surface H2
All sapwood & not less than X mm from any heartwood surface – whereTimber < = 35 mm, X = 5 Timber > 35 mm, X = 8
H3
All sapwood & not less than 10 mm from any surface H4
Currently
approved wood
preservatives in
Australia. . . .
- Water based
- Solvent based
H1 H2 H3 H4 H5 H6
CCA ✓ ✓ ✓ ✓ ✓ ✓
ACQ (Micronized) ✓ ✓ ✓ ✓ ✓
Copper azole ✓ ✓ ✓ ✓
Creosote ✓ ✓ ✓ ✓
Boron compounds ✓ ✓
Fluoride compounds ✓
Deltamethrin ✓ ✓ ✓
Cypermethrin ✓ ✓ ✓
Permethrin ✓ ✓ ✓
Tri (n-butyl) tin oxide ✓
Tri (n-butyl) tin naphthenate ✓
Propiconazole/tebuconazole ✓
Copper naphthenate ✓
Bifenthrin ✓ ✓
Chlorpyrifos ✓
Imidacloprid ✓
LOSP (Light Organic Solvent Preservatives)
• Dissolved in white spirit
• ~35 L/m3 to treat wood >> no redrying
Fungicides•TBTO
•TBTN
•Tebuconazole/ propiconazole
•Cu Nap
Insecticides•Permethrin
•Cypermethrin
•Bifenthrin
Are you asleep yet???
Regulatory requirements in Australia for preservative treatment
• Australian Pest & Veterinary Medicines Authority (APVMA)
– Federal Government agency
– Applicant submits efficacy data
– Data is assessed by an expert panel
– Approves all agricultural chemical formulations
– Approves a label which sets specifications for how a formulation may be used.
• Only concerned with biological attack
– Product may be adequately protected but may not be ‘fit for purpose’
• Does not directly specify how long a product is required to perform.
– Indirect through linking treatment requirements to natural durability
---
Treatment Specifications
• Australian Standards
– No legal authority unless specified
• Queensland
– Timber Utilization and Marketing Act – Stopped in October 2010
• New South Wales
– Timber Marketing Act – Stopped in 2012/13
– The three sets of specification are/were basically the same
There are approximately 150 timber treatment
systems in Australia
Compliance with specification
• There are no laws specifically applying to producing
treated timber
• Unless required by the buyer/specifier/user, there is
no requirement to check quality >> caveat emptor
• Large corporates have their own in-house quality
systems
• Private QA schemes are also available
---
Australian Standard – issues and evolution
• Consensus (All have to agree)
• Changing the Standard is very slow
• One set of specifications for the whole country
• Pressure to moving towards treatment to be fit for purpose
– Geography/location/environment
– Design life **
• New Zealand is involved and chooses which standard/
specification to use.
(** NZ has adopted explicit design life requirements whereas design life
is implied under the ABCB)
Treatment plants/ systems
• Vacuum Pressure (water based)
– CCA, ACQ, Cu Azole, boron
• LOSP Plants
• Sprays/ dips
– Permethrin, bifenthrin
• Glue line addition
– Bifenthrin, deltamethrin, imidacloprid
• Paint on – cosmetic rather than protection
Identifying treated timber
Plant ID Preservative Hazard class
754 02 H3
National register Listed in
AS1604.1
A claim by the producer
The brand in action
•If the treated product is not branded –you CAN NOT assume it is preservative treated (in accordance with the standard) regardless of any other form of certification! If the product fails at some time in the future, you have no recourse on the supplier.
•It is highly recommended that all brands on treated timber are retained in case there are any questions about treatment quality
Practicalities• There is a terrible lack of knowledge by specifiers and
users in Australia and this is a concern when all you have to do is ask!
• For some reason, using timber is not viewed as being environmentally responsible yet!!!!!!!!!
• Kg/m3 carbon factor during manufacture
• Timber – 1
• Concrete – 8
• Steel – 355
• Aluminium - 1466
• Fear of chemicals
• Timber industry is spread over a large area with only 4 large corporates.
• Large warehouse hardware suppliers squeezing prices and this is likely to impact on treatment quality
• No value in having rules if they are not monitored or checked
---
A mountain of information
Opportunities for improvement
• National quality management system . . . Concrete
is sampled on site for quality – why not timber?
• User education
– Industry/builders
– Tertiary institutions
• Targeting end use by geographic location with
more specific penetration and retention
specifications.
• Targeting product treatments
• Treatment of glue laminated timber
---
New/alternate treatment systems
• Natural wood preservatives
• Heat treatment
• Wood plastic composites
• Critical fluid treatments
• Modified wood
---
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