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protection remains functional
Durability - Hazards Biological/ Physical Hazards TIMBER Species Natural durability of heartwood Weathering Fire Chemical Design Detailing minimises exposure to hazards Treatment enhances durability of sapwood Fungi Termites / borers Marine Maintenance ensures protection remains functional
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Hazards Anything that may cause deterioration of timber during service
Reduce long-term performance Can counter the effects of hazards by Selection of appropriate species (Natural Durability) Treatment Detailing to minimize exposure to hazards Includes weathering, chemicals, fire No classification for these hazards – use appropriate detailing to minimize hazard impact Includes fungal, insect, marine organism attack Can classify according to Hazard Class scale
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Physical Hazards Weathering - degradation due to weather
rain sunlight Chemicals - timber performs well relative to steel/concrete resistant to degradation for pH>2 and pH<10 softwoods marginally better than hardwoods Fire - burning strength during fire insulation of walls prevention of spread
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Preventable problems Weathering Photo: Geoff Boughton Marmion, WA
Kangaroo Point, Qld Photo: Geoff Boughton Plamerston, NT Photo: Geoff Boughton
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Biological Hazards Fungi Termite/borers Marine organisms
Can classify according to Hazard Class scale
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Preventable problems Fungi damage Termite damage Marine borer damage
Photo: Geoff Boughton Fungi damage Photo: Geoff Boughton Photo: Geoff Boughton Termite damage Marine borer damage Horticultural Training Centre, Mornington, Tas Photo: Greg Nolan
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Hazard Class Hazard Class Exposure Service Conditions
Biological Hazard H1 Inside above ground Fully protected Well ventilated Borers only H2 Protected from wetting, nil leaching Borers and termites H3 Outside above ground Moderate wetting & leaching Decay borers and termites H4 Outside in ground Severe wetting & leaching Severe decay borers and termites H5 Ground contact Extreme wetting, leaching &/or critical use Very severe decay borers and termites H6 Marine waters north & south Prolonged immersion in sea water Marine wood borers and decay H6SW Marine waters south only
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Natural Durability (Heartwood)
Extractives and growth characteristics affect natural durability of timber species Class Durability Species 1 Highly durable Ironbark, Tallowwood, Cypress, Turpentine, Forest red gum 2 Durable Spotted gum, Blackbutt, River red gum, Western Cedar, Stringybark (yellow & white) 3 Moderately durable Brush box, Rose/flooded gum, Sydney blue gum, Silver topped stringy bark 4 Non-durable Douglas fir, Hoop pine, Radiata pine, Mountain ash/ Tasmanian oak, Unidentified timbers
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Long-term Performance of Timber
Can match natural durability class with environmental hazard to estimate long-term performance of untreated timber heartwood Natural Durability Class Heartwood Service Life (years) H1 fully protected H3 Above ground exposed H5 in-ground Class 1 50 + 25 + Class 2 30 15 – 25 Class 3 15 8 – 15 Class 4 5 - 8 < 5
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Hazard links to Treatment level
Treatment levels have classes with same names as the Hazard levels H1 – lowest level treatment – suitable for H1 hazard environments – indoors, protected H2 – treated timber suitable for H2 hazard environments –suitable for all internal use H3 – treated timber suitable for H3 hazard environments –suitable for above ground external use H4 – treated timber suitable for H4 hazard environments –suitable for use in contact with dry ground H5 – treated timber suitable for H5 hazard environments –suitable for all in-ground use
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H1 indoors, protected, ventilated Aged Care residence, Tapping, WA
Photo: Geoff Boughton Wall panels Holybank Forest Centre Lilydale, Tas Photo: Greg Nolan
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H2 all internal use, poorly ventilated
eg. concealed wall frames and floor timbers
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above ground external use
H3 above ground external use Queenscliffe Jetty, Vic. Photo: Greg Nolan Marina residence, SA Photo: Greg Nolan
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in contact with dry ground
Hardwood walkway, Margaret River, WA Photo: Geoff Boughton Play equipment, Geelong, Vic Photo: Geoff Boughton
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all in-ground use, critical, subject to wetting
H5 all in-ground use, critical, subject to wetting Nanga Camp, Dwellingup, WA Photo: Geoff Boughton Logging bridge, Pemberton, WA Photo: Geoff Boughton pole house, Townsville, Qld Photo: Geoff Boughton
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Marine use – prolonged immersion in sea water
H6 Marine use – prolonged immersion in sea water Bussleton Jetty, WA Photo: Geoff Boughton Bussleton Jetty, WA Photo: Geoff Boughton
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