Ironbark

Overview

If you want a timber that will last forever (or almost), then ironbark is what you’re looking for. The timber got its name because of its heaviness and high density. It is a difficult timber to work with due to its density, but has the highest possible durability rating of 1.

Ironbark is a beautiful timber, with colours ranging from pale brown to deep red. Aside from being one of the most durable timbers, ironbark is also highly fire, termite and rot resistant. If you’re looking for pool decking, high traffic areas, or fire resistance for that cabin in the bush, ironbark may be your best choice.

The common name “Ironbark” comes from the trees tendency to not shed its bark annually like many other eucalyptus, resulting in an accumulation of dead bark. This layer of bark protects the living tissue inside the tree from fires, and with a silvery-grey colour looks quite similar to iron metal or slag and hence the name.

There are two main Ironbark families, which are basically “Those that appear red in colour, and those that don’t”. In our region here in SEQ its predominately the reds.

Ironbark is usually seen growing, in both native forests and plantations, in the western area of NSW up to southern QLD, with some trees growing in northern VIC. Our Ironbark comes from the traprock region of QLD, widely sought after for its slow growing and dense properties. Like the country, "Trap rock" region Ironbark is hard wearing. Ironbark has a very high natural resistance to rot due to chemistry of the tree which helps fight off fungus.

The heartwood has a deep red colour which is a great contrast to the pale yellow sapwood. Both heartwood and sapwood are often seen together in decking boards. Ironbark timber has an interlocked grain with a fine texture. Ironbarks popularity is ever increasing with more and more homes using the timber for decks, landscaping and cladding due to its high durability and fire resistance.

Qualities

PROS

CONS

High rot and termite resistance

Hard to work

Very high durability, hardness and density

Boards need to be pre-drilled

Widely available

Expensive

Used for over 200 years in heavy construction

Short oil life of decking due to density

Little tannin leach

Mostly supplied in random lengths

1 of 7 hardwoods recommended by the building commission for bushfire prone areas > See Details

 

Properties

NAME

Eucalyptus Sideroxylon (red)
Eucalyptus Paniculata (grey)

Eucalyptus Crebra (Red)

COLOUR (Heartwood)

Light grey / chocolate to deep red

COLOUR (Sapwood)

Pale yellow

DURABILITY

Class 1

DENSITY

1090 kg/m3

HARDNESS

Janka rating 14

AVAILABILITY

Readily Available

BAL RATING

Grey
12.5
19
Red
12.5
19
29

TERMITE RESISTANT

YES

LYCTID BORER SUSCEPTIBLE

NO (grey)
YES (red)

TANNIN LEACH

Little

ORIGIN

VIC, NSW, QLD