durability - hazards biological/ physical hazards weathering fire chemical timber species natural...
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Durability - Hazards
Biological/ PhysicalHazards
WeatheringFireChemical
TIMBER
SpeciesNatural durability of heartwood
Maintenance ensures protection remains functional
Treatmentenhances durability
of sapwood
FungiTermites / borersMarine
Design Detailingminimisesexposure
to hazards
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
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
Preventable problems
Weathering
Kangaroo Point, QldPhoto: Geoff Boughton
Plamerston, NTPhoto: Geoff Boughton
Marmion, WAPhoto: Geoff BoughtonPhoto: Geoff Boughton
Biological Hazards
Fungi Termite/borers Marine organisms
Can classify according to Hazard Class scale
Preventable problems
Fungi damage
Marine borer damageTermite damage
Photo: Geoff Boughton
Photo: Geoff BoughtonPhoto: Geoff Boughton
Horticultural Training Centre, Mornington, Tas
Photo: Greg Nolan
Hazard ClassHazard Class
Exposure Service Conditions Biological Hazard
H1 Inside above ground Fully protectedWell ventilated
Borers only
H2 Inside above ground 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
Prolonged immersion in sea water
Marine wood borers and decay
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
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)
Heartwood Service Life
(years)
Heartwood Service Life
(years)
H1 fully protected
H3 Above ground
exposed
H5 in-ground
Class 1 50 + 50 + 25 +
Class 2 50 + 30 15 – 25
Class 3 50 + 15 8 – 15
Class 4 50 + 5 - 8 < 5
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
H1indoors, protected, ventilated
Aged Care residence, Tapping, WA
Photo: Geoff Boughton
Wall panels Holybank Forest Centre Lilydale, TasPhoto: Greg Nolan
H2all internal use, poorly ventilated
eg. concealed wall frames and floor timbers
H3above ground external use
Marina residence, SA Photo: Greg Nolan
Queenscliffe Jetty, Vic. Photo: Greg Nolan
H4
in contact with dry ground
Play equipment, Geelong, VicPhoto: Geoff Boughton
Hardwood walkway, Margaret River, WA
Photo: Geoff Boughton
H5all in-ground use, critical, subject to wetting
pole house, Townsville, QldPhoto: Geoff Boughton
Nanga Camp, Dwellingup, WAPhoto: Geoff Boughton
Logging bridge, Pemberton, WAPhoto: Geoff Boughton
H6Marine use – prolonged immersion in sea water
Bussleton Jetty, WAPhoto: Geoff Boughton
Bussleton Jetty, WAPhoto: Geoff Boughton