Durability - Hazards

Biological/ PhysicalHazards

WeatheringFireChemical

TIMBERSpeciesNatural 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 Boughton Photo: 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 protectedH3

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 levelTreatment 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

H4in 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