Tallowood (Eucalyptus microcorys)

Tallowood is an extremely hard, durable and versatile Australian native hardwood species. Its timber products are suitable for a wide range of applications.

Tallowwood is a moderate to large tree occurring in wet sclerophyll forests of coastal regions from the Hunter River district of New South Wales to Maryborough and Fraser Island, Queensland.

The heartwood of this species ranges in colour from pale to dark yellow-brown, with occasional tinges of olive green. Sapwood is a whitish colour. The texture of Tallowwood timber is moderately coarse, generally with interlocked grain. Unusually for a eucalypt species, Tallowwood is free of gum veins. Figure is lacking but the timber possesses a distinctive lustre and ‘greasy’ appearance.

Tallowwood timber products exhibit exceptional durability in both in-ground and aboveground applications, where life expectancy is greater than 25 and 40 years, respectively. Although Tallowwood is highly resistant to decay and will withstand damp and wet conditions quite well, its sapwood is susceptible to Lyctid borer (powder post beetle) attack. Untreated timber of this species is equivalent to ‘fire retardant treated timber’ when tested in accordance with AS/NZS 3837.

Historically, Tallowwood has been used for bearings, mallet heads, mauls, wheel spokes, and tool handles. Current engineering applications include wharf and bridge construction (as sawn and round timber), railway sleepers, cross-arms, poles, piles and mining timbers. Construction uses range from unseasoned framing to dressed timber cladding, internal and external flooring, linings and joinery. Tallowwood is also used in fencing, landscaping and the construction of retaining walls. Decorative uses include outdoor furniture, turnery and joinery. Other applications include boat building, the construction of coaches, carriages and agricultural machinery, and structural plywood.

SHRINKAGE

  Very Low Low Medium High Very High
This is the measure of the percentage reduction in dimension from the unseasoned to 12% moisture content condition.
Tangential This is the measure of the percentage reduction
6.1
Radial
3-4
Unit Movement
0.37%

STRENGTH GROUPS

  Very High High Reasonably High Medium High Medium Reasonably Low Low Very Low
Uneasoned
S1
S2
S3
S4
S5
S6
S7
Seasoned
SD1
SD2
S3
SD4
SD5
SD6
SD7
SD8

STRESS GRADE A stress grade is defined in AS 1720 as the classification of timber for structural purposes by means of either visual or machine grading. The stress grade indicates the basic working stresses and stiffnesses to be used for structural design purposes. Measured in MPa.

  Structural No 1 Structural No 2 Structural No 3 Structural No 4 Structural No 5
Unseasoned
F27
F17
F14
F11
F8
Seasoned
F34
F27
F22
F17
F14

DENSITY PER STANDARD Seasoned density is based on moisture content of 12%. Unseasoned density is an approximation as it depends on the moisture content at the time of measurement. Measured kg/m3.

Unseasoned 1230kg/m3
Seasoned 990kg/m3

JOINT GROUP The joint group is a classification of the strength of a species in joint design. The values are from 1 (very high strength) to 6 (very low strength)

  Very High High Reasonably High Medium Low Very Low
Unseasoned
J1
J2
J3
J4
J5
J6
Seasoned
JD1
JD2
JD3
JD4
JD5
JD6

COLOUR The colour of seasoned heartwood can vary between species and often within a species. The information provided should be used as a general guide only. In most cases, the colour of sapwood is either a lighter shade of the heartwood or a white/cream colour

  White, Yellow,Pale Straw to Light Brown Pink to pink brown Light to dark red Brown, chocolate, mottled or streaky
Shade
 

MECHANICAL PROPERTIES

Modulus of Rupture – Unseasoned
106
Modulus of Rupture – Seasoned
134
Modulus of Elasticity – Unseasoned
18
Modulus of Elasticity – Seasoned
18
Maximum Crushing Strength – Unseasoned
51
Maximum Crushing Strength – Seasoned
73
Impact – Unseasoned
20
Impact – Seasoned
17
Toughness – Unseasoned
Medium – 15 – 25 Nm
Toughness – Seasoned
Medium – 15 – 25 Nm
Hardness – Unseasoned
7.6
Hardness – Seasoned
8.6
 
 

DURABILITY

  Low Moderate Reasonably High High
 
(0-5 years)
(5-15 years)
(15-25 years)
(> 25 years)
In Ground  
 
(0-7 years)
(7-15 years)
(15-40 years)
(>40 years)
Above Ground    
  (0-20 years, usually <5) (21-40 years) (41-64 years) (>65 years)
Marine Borer Resistance    
 
Lyctid Borer Susceptibility
Susceptible
Termite Resistance
Resistant

FIRE PROPERTIES

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
EFH Ignitability
                     
             
                                       
EFH Spread of Flame Index
1
2
3
4
5
6
7
8
9
10
             
           
                                       
EFH Smoke Developed Index
1
2
3
4
5
6
7
8
9
10
   
           
                                       
Critical Radiance Flux – Lower
>2.2 and <4.5kWm 2
Critical Radiance Flux – Higher
>4.5kWm 2
Smoke Development Rating
<750
Fire Properties Group Number
1 – Non Combustible
2 – reasonably non combustible
3 – slightly combustible
4 – combustible
                   
         
                                       
Average Specific Extinction Area
<250
Bushfire Resistance
BAL 12.5, 19 and 29 – All AS3959 required applications
                                         

Botanical Name:

Eucalyptus microcorys

Common Name:

Tallowood

AKA:

Tallow wood

Type:

Hardwood

Appearance

The heartwood of this species ranges from pale to dark yellow-brown, in contrast to its typically whitish sapwood. The texture of Tallowwood timber is moderately coarse, generally with an interlocked grain relatively free of gum veins. Figure is lacking, but Tallowwood possesses a distinctive lustre and greasy appearance.

Common Applications

Historically, Tallowwood has been used for bearings, mallet heads, mauls, wheel spokes, and tool handles. Current engineering applications include wharf and bridge construction (as sawn and round timber), railway sleepers, cross-arms, poles, piles and mining timbers. Construction uses range from unseasoned framing to dressed timber cladding, internal and external flooring, linings and joinery. Tallowwood is also used in fencing, landscaping, and the construction of retaining walls. Decorative uses include outdoor furniture, turnery and joinery. Other applications include boat building, the construction of coaches, carriages and agricultural machinery, and structural plywood.

Common Form

Sawn

Workability

Tallowwood is very hard (rated 1 on a 6-class scale) in relation to indentation, yet is relatively easy to work with hand tools due to the timber’s natural greasiness – hence the species’ common name. It machines and turns well, readily accepts paint, stain and polish, and is amenable to the use of standard fittings and fastenings. Pre-drilling is recommended for nailing and screwing. Numerous extractives render Tallowwood difficult to bond satisfactorily, although success has been reported with the use of polyurethane glues.

Decking

Timber decking creates spaces that are functional, practical and aesthetically pleasing. With the right design and care a timber deck will make a valuable addition to any home or business, creating an outdoor living space that will be enjoyed for years to come.

External Cladding

The natural appeal, versatility and strength of timber makes it the superior choice for external cladding. Through specification, planning, design and finishing processes, timber cladding not only creates a building of superior strength, acoustic and thermal performance but also creates a place of beauty, style and natural appeal.

Fencing

When it comes to fencing, timber is your natural choice. A material that is durable, strong and reliable it compliments almost every outdoor landscape and environment. Clear specification, detailed installation and appropriate maintenance will see any timber fence provide a natural and lasting property boundary and back drop for years to come.

Flooring

Whether for structural or finished flooring applications, timber offers durability, versatility and adaptability. The warmth, strength and natural beauty of timber flooring has proved enduringly popular in a wide variety of interior settings.

Framing

Since people began building simple shelters, wooden framing has played an important role in shaping structures of many kinds. One of the most popular types of wooden framing is known as lightweight timber construction.

Internal Panelling

Timber paneling creates interiors as warm as they are stylish. Commonly utilising an MDF or plywood substrate, internal timber paneling is natural and versatile and comes as either solid natural timber panels or as sheets of engineered wood products

Pergolas

A timber pergola is a practical, functional and attractive way to extend living and entertainment spaces into the outdoors.

Retaining Walls (Landscaping)

When it comes to retaining wall, landscape design and construction, timber is the natural choice. A material that is durable, sturdy and reliable, it boasts natural aesthetics that help it blend seamlessly with the outdoors. Careful consideration during the specification and design process will facilitate the creation of a long lasting, durable and eye catching timber retaining wall that will complement its surrounding landscape for years to come.

Structural Timber Posts

Timber poles are utilised in structural construction to provide support for gravity loads and resistance against lateral forces. Not only serving a structural function, timber poles provide many aesthetic benefits, with their use in construction often complementing architectural designs aimed at harmonisation with the natural environment.

Timber Joinery Products

Timber joinery products offer a classic, unique and stylish touch to any interior design.

Timber Portal Frames

For buildings that require large spans and column free interiors, timber portal frames provide one of the most aesthetically pleasing solutions. Utilising modern engineering technology, portal frame design transforms timber into a highly effective, efficient and economical structural product. This application guide provides a comprehensive overview of the process of using timber in the specification, fabrication and erection of portal frame structures.