Redwood

Redwood’s rich colouring and durability make it a good choice for use indoors and out.

Other Names

Californian Redwood, Coast Redwood, Sequoia

Botanical Name

Sequoia sempervirens

Common Form
Sawn
Species Type
Softwood
  • Overview

    • The Sequoia or California redwood is one of the world's most recognisable trees. The strength and rich colours of its softwood timber make it much sought after for decorative purposes, such as paneling, and for outdoor purposes such as decking, fences and garden furniture. 

    The heartwood is pale to dark reddish brown, and the sapwood narrow and creamy. Texture is fine and usually even, because there is little difference between the early and late wood. The grain is straight and the wood is not resinous.

    Redwood works easily with both hand and machine tools, with little dulling effect on tools. It planes well, provided the cutters are sharp and it splinters easily when working on the end grain. It holds nails well, and paints and finishes satisfactorily. It also stains well, but glues best with alkaline adhesives. The heart wood is more resistant to decay and insects than the sap wood.

    The distinctive and very attractive colouring of redwood makes it highly sought after for decorative purposes, such as paneling and cladding, while its resistance to weather and insects makes it a natural choice for external joinery, outdoor furniture, windows and greenhouses. Similarly, its durability makes it useful for vats and tanks.

    Today in the USA, a total of 364,000 ha of second growth forest are under active management for timber production. 

    Significant quantities of California redwood were imported last century. Once readily available in Australia, it is now difficult to source as new timber. Australian red cedar  is a possible substitute.

    Shrinkage

    Very Low Low Medium High Very High
    Check mark Check mark Check mark

    Tangential : Provides a simplified rating for tangential shrinkage. This is the measure of the percentage reduction in dimension from the unseasoned to 12% moisture content condition.
    1.90%

    Radial : Radial shrinkage is perpendicular to the growth rings. It is shrinkage in the direction towards the centre of the tree. Measurement is % value
    1.10%

    Unit Movement Tangential: This is the percentage of dimensional change for each 1% moisture content change between about 3% moisture content and the fibre saturation point for the particular species.
    0.12%

    Unit Movement Radial: This is the percentage of dimensional change for each 1% moisture content change between about 3% moisture content and the fibre saturation point for the particular species.
    0.21%

    Strength Group Strength groups are given for unseasoned (S1-S7) and seasoned (SD1-SD8) timber in accordance with AS 2878. S1 and SD1 yield the highest strength and stiffness whereas S7 and SD8 yield the lowest.

    Very High

    High

    Reasonably High

    Medium High

    Medium

    Reasonably Low

    Low

    Very Low

    Unseasoned:

    S1

    S2

    S3

    S4

    S5

    S6

    S7

    S8
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    Seasoned:

    SD1

    SD2

    SD3

    SD4

    SD5

    SD6

    SD7

    SD8
    Check mark

    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:

    F8

    F7

    F5

    F4

    Seasoned:

    F11

    F8

    F7

    F5

    F4

    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.

    Seasoned:

    400kg/m3

    Unseasoned:

    710kg/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
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    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
       
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    Mechanical Properties

    Modulus of Rupture - Unseasoned: This property is a measure of maximum stress which timber can momentarily sustain when loaded slowly and continuously as a beam. Measured in MPa.
    52

    Modulus of Rupture - Seasoned: This property is a measure of maximum stress which timber can momentarily sustain when loaded slowly and continuously as a beam. Measured in MPa.
    69

    Modulus of Elasticity - Unseasoned: This property is of importance in determining the deflection of a beam under load — the greater the stiffness, the less the deflection. Measured in GPa.
    8.1

    Modulus of Elasticity - Seasoned: This property is of importance in determining the deflection of a beam under load — the greater the stiffness, the less the deflection. Measured in GPa.
    9.2

    Maximum Crushing Strength - Unseasoned:

    Also referred to as compression strength. This property measures the ability of the timber to withstand loads applied on the end grain. Measured in MPa.
    29

    Maximum Crushing Strength - Seasoned: Also referred to as compression strength. This property measures the ability of the timber to withstand loads applied on the end grain. Measured in MPa.
    42

    Impact - Unseasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.

    Impact - Seasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.

    Toughness - Unseasoned: This is a measure of timber’s ability to resist shocks and blows, and is synonymous with impact strength. It is measured in Nm.
    Medium - 15 - 24 Nm

    Toughness - Seasoned: This is a measure of timber’s ability to resist shocks and blows, and is synonymous with impact strength. It is measured in Nm.
    Low - up to 15 Nm

    Hardness - Unseasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    1.8

    Hardness - Seasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    2.1

    Durability

    Low Moderate Reasonably High High
    (0 - 5 yrs) (5 - 15 yrs) (15 - 25 yrs) (more than 25 yrs)

    In-Ground: Durability is defined as the inherent resistance of a timber species to decay, or to insect or marine borer attack. All references to durability refer to the heartwood only. A scale of low to high (durability class 4 = low; 1 = high) has been adapted for above and in-ground durability.

    		 Check mark
    (0 - 7 yrs) (7 - 15 yrs) (15 - 40 yrs) (More than 40 yrs)

    Above ground: Durability is defined as the inherent resistance of a timber species to decay, or to insect or marine borer attack. All references to durability refer to the heartwood only. A scale of low to high (durability class 4 = low; 1 = high) has been adapted for above and in-ground durability.

    		 Check mark
    (0 - 20 yrs, usually < 5) (21 - 40 yrs) (41 - 64 yrs) (More than 60 yrs)

    Marine Borer Resistance: Indicates whether a species is resistant (R) or not resistant (NR) to marine borer attack.

    		 Check mark

    Lyctid Borer Susceptibility: Indicates whether a species is susceptible (S) or not susceptible (NS) to lyctid borer attack.

    Not Susceptible

    Lyctid Borer Susceptibility - Other:

    Termite Resistance: Indicates whether a species is resistant (R) or not resistant (NR) to termites.

    Resistant

    Fire Properties

    0 1 2 3 4 5 6 7 8 9 10

    EFH Spread-of-Flame Index: This is a material's propensity to burn rapidly and spread flames based on a scale of 0 to 10 where 0 means that the materials will not cause flames to reach the ceiling and 10 indicates that the material could be expected to cause flames to reach the ceiling of a room within 10 seconds of ignition.

    EFH Smoke-Developed Index:This is a measure of the concentration (measured by optical density) of smoke a material emits as it burns. It is based on an arbitrary scale of 0 to 10. The higher the index, the greater the hazard from smoke is likely to be.

    Bushfire Resistance: Naturally bushfire-resisting timbers are those with inherent bushfire-resisting properties. Some species have been tested and a number are in the process of being tested and are measured by Bushfire Attack level (BAL). BAL -12.5: Ember attack, BAL – 19: Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 12.5 and 19 kWm3, BAL – 29: Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 19 and 29 kWm3.
    Not Tested
    Appearance

    Redwood heartwood is pale to dark reddish brown and the sapwood narrow and creamy. Texture is fine and usually even because there is little difference between the early wood and the late. The grain is straight and the wood is not resinous.

    Common Applications

    The distinctive colouring of redwood makes it highly sought after for decorative purposes, such as for paneling and cladding, while its resistance to weather and insects makes it a natural choice for external joinery, outdoor furniture, windows and greenhouses. Similarly, its durability makes it useful for vats and tanks.

    Workability

    Redwood works easily with both hand and machine tools, with little dulling effect on tools. It planes well, provided the cutters are sharp, but it splinters easily when working on the end grain. It holds nails well, and paints and finishes satisfactorily. It also stains well, but glues best with alkaline adhesives.

    Origin of timber
    VIC
    Significant quantities of California Redwood were imported last century. Once readily available in Australia, it is now difficult to source as new timber. Australian red cedar is a possible substitute.
    Source of timber
    Native Forest

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