Hemlock, Western

Western hemlock is a softwood native to North America. It produces a lustrous pale timber that is an attractive choice for carving.

Other Names

West Coast Hemlock, Pacific Coast Hemlock, Alaska Pine, Hemlock Spruce, British Columbian Hemlock, Canada Pine, Hem Fir

Botanical Name

Tsuga heterophylla

Common Form
Sawn
Species Type
Softwood
  • Overview

    • Western hemlock is a valuable tree with many commercial uses. It is often marketed as Hem-fir, as it has similar design values to the true firs: California red, grand fir, noble fir, Pacific silver fir and white fir. It is one of ten hemlock species and is considered a premium timber.

     

    Western hemlock is an evergreen tree from North America. It grows prolifically from the coastline of northern Sonoma County, California, north to the Kenai Peninsula, Alaska and east to Idaho and Montana, and is widely harvested in these regions.

    Growing from 30 to 50 metres tall, trees are characterised by small oval cones and flat, short needles. Their cinnamon coloured bark is furrowed and attractive.

    The timber is used in construction but as a softwood is not durable and requires treatment for external use. External and interior construction applications include joinery, cabinetry, flooring, and ceilings. It also is a popular choice for creating doors, windows, parts of staircases, ladders, flooring, paneling, broom handles, crates, pallets and packing cases as well as other architectural millwork items.

    Western hemlock is one of the best pulp woods for paper and paperboard products. Traditionally, however, Indigenous artisans used the easily worked timber for carving into spoons, combs, roasting spits and giant feast dishes.

    In agro-forestry, western hemlock is used to help reduce stream bank erosion, and increase biodiversity. It has been used to produce dimethyl sulfide, the substance that gives an odour to natural gas, which could otherwise go undetected; and conidendrol, produced from Hemlock wastes, which slows oxidation.

     

    Shrinkage

    Very Low Low Medium High Very High
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    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.
    4.90%

    Radial : Radial shrinkage is perpendicular to the growth rings. It is shrinkage in the direction towards the centre of the tree. Measurement is % value
    2.50%

    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.
    0.27%

    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.
    0.14%

    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
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    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:

    F14

    F11

    F8

    F7

    F5

    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:

    505kg/m3

    Unseasoned:

    780kg/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
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    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.
    46

    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.
    78

    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.
    9

    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.
    11.3

    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.
    23

    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.
    49

    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.
    Low - up to 15 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.
    2.4

    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.

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    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.

    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: A measure of the tendency of a material to ignite measured on a scale of 0 – 20. An index of 0 indicates that the material did not ignite during the 20 minutes that the test takes. An index of 20 indicates that the material ignited in the first minute.
    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.
    1 - non-combustible 2 - reasonably non-combustible 3 - slightly combustible 4 - combustible

    Fire Properties Group
    Number:

    Group Number - Other:
    3 if used on MDF or particleboard ≥12mm; veneer thickness 0.6-0.85mm

    Average Specific Extinction Area: This value is determined by the volume of smoke measured over the mass loss of the tested sample per test carried out in accordance with ‘Cone Calorimeter Test’ AS/NZS 3837. It is measured in units of m2/kg.
    <250

    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

    Timber of the western hemlock has a natural lustre. The tree's heartwood has a pale, cream colour with distinctive growth marks and a fairly even texture. This beautiful pale timber produces few knots and displays a uniform, attractive grain. Sometimes western hemlock can display a slight lavender cast, especially around the knots and in the transition area between the spring and summerwood growth rings. Attractive, delicate, dark grey or black streaks may be apparent in the wood. There is little variation in colour between the heartwood and sapwood, and they are often indistinguishable from one another.

     

    Common Applications

    Western hemlock timber is used in construction but is not recommended for external use without treatment. Preservative pressure-treated timber products are both visually appealing and strong, and among the more economical species for decks and other outdoor amenities. Internal uses include joinery and cabinetry. 

    Some timbers of this species are fine grained and even textured, lending themselves to attractive wood paneling and trims, windows, parts of staircases, and flooring. Handsome solid wood doors, louvers, shutters, moulding and furniture can all be manufactured from Western Hemlock.

    The timber has been used to make broom handles, and case goods such as crates, pallets and packing cases and other architectural millwork items. It is one of the best pulp woods for paper and paperboard products.

    Lower-grade knotty products are useful for those utilitarian applications in construction where economy governs, such as stud walls.

    Workability

    Light in weight and straight in grain, western hemlock's workability has been compared to that of pine, although it does weigh 480kg/cubic metre when seasoned. Builders favour this species because it is resistant to splitting, holds nails and screws securely and saws easily without splintering.

     

    The initially high moisture content of western hemlock demands careful drying to avoid surface checking and ensure uniform drying in thick stock.

    The wood has an even grain and resists scraping, which makes it easy to machine. Western hemlock timber has a moderate steam-bending rating and works well with both hand and machine tools with little dulling of cutting edges. This timber has medium bending and crushing strength. It is not hard or stiff, giving it low durability. Timber of this species can be easily glued, stained, painted or varnished.

     

    Origin of timber
    North America
    Readily Available
    NSW
    Western hemlock has limited availability in all states except Queensland, Victoria and New South Wales, where it is common.
    Source of timber
    Native Forest

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