Ash, Silvertop | Eucalyptus sieberi

Silvertop ash is a large Australian hardwood that is commonly used for general construction and flooring.

Other Names: Coast Ash, Ironbark, Silvertop, Black Ash, Eucalyptus sieberiana

Overview

Silvertop ash is a large, moderately durable Australian hardwood that grows in the southern and central coast and tablelands of New South Wales, eastern Victoria and north eastern Tasmania. It is also known as ‘coast ash’ due to its occurrence along the coastal areas of the cooler eastern states.

Of medium texture, silvertop ash has an interlocked grain and with noticeable growth rings. The heartwood is brown, sometimes pinkish and the sapwood is narrow in appearance. Gum veins, markings from pinhole borers and pencil streaks also distinguish the appearance of silvertop ash.

Care needs to be taken when drying silvertop ash, because of its proneness to surface checking on the tangential surface. It is also slow to dry.

Silvertop ash provides good fire resistance, and is one of seven hardwood timber species that was found to be suitable by the Building Commission in Victoria for home construction in bushfire areas (provided it has a thickness greater than 18 mm).

It is mainly used for general construction, but is also used for flooring, furniture, handles, joinery, fence posts, cases and chemical pulp.

 

Properties

Shrinkage

Very Low Low Medium High Very High
Tangential:          
10.6
Radial: > 5
Unit Movement: 0.36 %

Strength Group

Very High High Reasonably High Medium High Medium Reasonably Low Low Very Low
Unseasoned:S1S2S3S4S5S6S7
Seasoned:SD1SD2SD3SD4SD5SD6SD7SD8

Stress Grade

Structural
No. 1
Structural
No. 2
Structural
No. 3
Structural
No. 4
Structural
No. 5
Unseasoned: F17 F14 F11 F8 F7
Seasoned: F27 F22 F17 F14 F11

Density per Standard

Unseasoned: 1200 kg/m3
Seasoned: 850 kg/m3

Joint Group

Very High High Reasonably High Medium Low Very Low
Unseasoned:J1J2J3J4J5J6
Seasoned:JD1JD2JD3JD4JD5JD6

Colour

  White, yellow, pale straw to light brown Pink to pink brown Light to dark red Brown, chocolate, mottled or streaky
   

Mechanical Properties

Modulus of Rupture - Unseasoned: 69
Modulus of Rupture - Seasoned: 136
Modulus of Elasticity - Unseasoned: 10
Modulus of Elasticity - Seasoned: 17
Maximum Crushing Strength - Unseasoned: 38
Maximum Crushing Strength - Seasoned: 70
Impact - Unseasoned: 12
Impact - Seasoned: 20
Toughness - Unseasoned: Medium - 15 - 25 Nm
Toughness - Seasoned: Medium - 15 - 25 Nm
Hardness - Unseasoned: 7.2
Hardness - Seasoned: 9.5

Durability

Low Moderate Reasonably High High
(0 - 5 yrs) (5 - 15 yrs) (15 - 25 yrs) (more than 25 yrs)
In-Ground:
(0 - 7 yrs) (7 - 15 yrs) (15 - 40 yrs) (More than 40 yrs)
Above ground:
(0 - 20 yrs, usually < 5) (21 - 40 yrs) (41 - 64 yrs) (More than 60 yrs)
Marine Borer Resistance:
Lyctid Borer Susceptibility: Not Susceptible
Termite Resistance: Not Resistant

Fire Properties

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
EFH Ignitibility:
0 1 2 3 4 5 6 7 8 9 10
EFH Spread-of-Flame Index:
EFH Smoke-Developed Index:
Critical Radiance Flux - Lower: >2.2 and <4.5 kW/m2
Critical Radiance Flux - Higher: >2.2 and <4.5 kW/m2
Smoke Development Rate: <750
1 - non-combustible 2 - reasonably non-combustible 3 - slightly combustible 4 - combustible
Fire Properties Group
Number:
Average Specific Extinction Area: <250
Bushfire Resistance: Bushfire Attack Level (BAL) 12.5, 19 and 29 - All AS 3959 Required Applications

Description

Botanical Name: Eucalyptus sieberi
Preferred Common Name: Ash, Silvertop
Other Names: Coast Ash, Ironbark, Silvertop, Black Ash, Eucalyptus sieberiana
Species Type: Hardwood

Appearance

Silvertop ash has a narrow sapwood, which is not clearly distinguishable from the heartwood. Its heartwood is brown and sometimes pinkish in colour and often features the grain interlocked with growth rings.

With a medium texture, silvertop ash is also recognisable by the common occurrence of gum veins, the markings of pinhole borers and pencil streaks.

Common Applications

Silvertop ash is mainly used as a building timber, such as in timber framing, It is often used for building framework on the south coast and tablelands of NSW. It is strong and reasonably durable, plus it has also been found to provide good fire resistance.

Other common applications include flooring, furniture and high-end joinery. Silvertop ash is also used for vehicle construction, handles, fence posts, cases and chemical pulp.

Common Form

Sawn

Workability

A tough, moderately durable timber, silvertop ash is reasonably easy to work. It machines well and can be worked with standard woodworking tools. It is easy enough to split along the rays, and it was for this reason that the pioneers used silvertop ash for roof shakes.

It accepts most coatings and is excellent for nailing and screwing. Silvertop ash sands well but is inclined to splinter. It is also suitable for steam bending. 

Origin of Timber

NSW, VIC, TAS

Availability - Further Information

Silvertop Ash is commonly available throughout Australia, especially in New South Wales.

Source of Timber

Native Forest

Applications

  • 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.

  • 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.

  • Structural Timber Poles

    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.

Case Studies

  • ARkit Prefab and Prefabricated Eco Homes

    Prefab and Prefabricated Eco Homes Australia: ARkit’s timber kit homes change the way we think about sustainable building and living.

    Applications: Decking, External Cladding, Flooring, Framing, Internal Paneling, Windows,

  • Cranbourne Botanic Gardens Visitor Centre

    The new Visitor Centre in the Australian Garden of the Royal Botanic Gardens, Cranbourne becomes a model of sustainable design the public can apply at home.

    Applications: Decking, Doors, External Cladding, Framing, Windows,

  • Kew House 3

    Vibe Design Group’s, Kew House 3 uses timbers natural warmth and appeal to not only wrap a dynamic exterior but also evoke a journey of discovery within the home.

    Applications: Decking, External Cladding, Fencing, Flooring, Timber Joinery Products,

  • Peninsula Hot Springs

    At the Peninsula Hot Springs Gregory Burgess Architects use timber to create environments that enhance the spirit.

    Applications: Decking, External Cladding, Flooring, Framing, Interior Stairs, Structural Timber Poles,

  • Svarmisk Resort Centre, Mt Beauty

    A striking eco-resort that embodies the essence of new and recycled timber working together to form a unique, innovative and sustainable development.

    Applications: External Cladding, Flooring, Framing, Interior Rails and Balustrades, Interior Stairs, Internal Paneling, Pergolas, Shear walls, Structural Timber Poles,

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