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Fir, Douglas

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Douglas fir is one of the world’s best-known timber species. Native to the west coast of North America, it is forested extensively in timber plantations throughout Europe, New Zealand and South America – regions where the species has become naturalised. Sawn timber from this species is readily available in Australia.

The heartwood of Douglas fir ranges in colour from yellow through orange to a deep reddish brown. Sapwood is often distinctively paler, occurring in a band from 50 to 75 millimetres in width, depending on the timber’s source. Grain is generally straight, with a pronounced difference in colour between earlywood and latewood that results in a highly distinctive figure on back-sawn surfaces. Texture is often coarse and uneven.

The timber machines and turns well, but planer blades must be kept sharp in order to avoid surface ridging. Care is required with the use of standard fastenings and fittings, as nails may tend to follow the timber’s growth rings. Douglas fir can be satisfactorily bonded using standard glues and procedures. Due to the timber’s high resin content and occasional earlywood–latewood ridging of the dressed product, care is required in selecting timber for finishing applications and in preparation of surfaces for paints and varnishes.

Douglas fir is only moderately durable, and both sapwood and heartwood resist impregnation with preservatives. The timber lacks termite-resistance and sapwood is susceptible to lyctid borer attack.

Douglas fir is commonly found as sawn timber in weather-protected heavy construction applications such as mining timbers, posts and poles. Treated pilings and boards are used in marine structures and for landscaping. Other common applications include general house framing, flooring, lining, fascias, bargeboards and pergolas. It is also used in joinery, turnery, carving and plywood.

 

Appearance

The heartwood of Douglas fir ranges in colour from yellow through orange to a deep reddish brown. Sapwood is often distinctively paler, occurring in a band from 50 to 75 millimetres in width, depending on the timber’s source. Grain is generally straight with a pronounced difference in colour between earlywood and latewood that results in a highly distinctive figure on back-sawn surfaces. Texture is often coarse and uneven.

Common Applications

Douglas fir is commonly found as sawn timber in weather-protected heavy construction applications such as mining timbers, posts and poles. Treated pilings and boards are used in marine structures and for landscaping. Other common applications include general house framing, flooring, lining, fascias, bargeboards and pergolas. It is also used in joinery, turnery, carving and plywood.

Common Form

Sawn

Workability

The timber machines and turns well but planer blades must be kept sharp in order to avoid surface ridging. Care is required with the use of standard fastenings and fittings, as nails may tend to follow the timber’s growth rings. Douglas fir can be satisfactorily bonded using standard glues and procedures. Due to the timber’s high resin content and occasional earlywood–latewood ridging of the dressed product, care is required in selecting timber for finishing applications and in preparation of surfaces for paints and varnishes.

Origin of Timber

NSW

Readily Available

NSW

Availability - Further Information

Douglas fir has been imported into Australia in large sections and long lengths for many years. It is readily available throughout mainland Australia.

Availability - Further Information

Plantation

Shrinkage

Very Low Low Medium High Very High

Tangential :

4.60%

Radial:

2.60%

Unit Movement Tangential:

0.26%

Unit Movement Radial:

0.15%

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

Seasoned:

SD1

SD2

SD3

SD4

SD5

SD6

SD7

SD8

Stress Grade

Structural
No. 1
Structural
No. 2
Structural
No. 3
Structural
No. 4
Structural
No. 5

Unseasoned:

F11

F8

F7

F5

F4

Seasoned:

F17

F14

F11

F8

F7

Density per Standard

Seasoned:

550kg/m3

Unseasoned:

700kg/m3

Joint Group

Very High

High

Reasonably High

Medium

Low

Very Low

Unseasoned:

J1

J2

J3

J4

J5

J6

Seasoned:

JD1

JD2

JD3

JD4

JD5

JD6

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:

47-53

Modulus of Rupture - Seasoned:

82-90

Modulus of Elasticity - Unseasoned:

8-11.1

Modulus of Elasticity - Seasoned:

10.3-13.6

Maximum Crushing Strength - Unseasoned:

21.4-26.7

Maximum Crushing Strength - Seasoned:

43.0-51.3

Impact - Unseasoned:

Impact - Seasoned:

Toughness - Unseasoned:

Low - up to 15 Nm

Toughness - Seasoned:

Low - up to 15 Nm

Hardness - Unseasoned:

2.10- 2.2

Hardness - Seasoned:

3.0 - 3.6

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

Lyctid Borer Susceptibility - Other:

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:

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:

< 250

Bushfire Resistance:

Not Tested

Joinery

Timber joinery products offer a classic, unique and stylish touch to any interior or exterior design. The products are produced for a variety of internal applications including door and window frames, cabinetry, skirtings, mouldings and architraves. When looking to the outdoors, joinery products range from decorative eaves and posts to eye-catching railings.

Many timber species are suitable for joinery products and care should be taken in selecting the perfect timber for the particular product and its intended finish. Rare and exotic species such as Teak and Rosewood can generate pieces of outstanding beauty but material cost and availability are also important considerations.

Commercially available species like Tasmanian oak, Australian cypress, spotted gum and the like, often make the more practical choice, with the added benefit that they can be easily matched with other timber products within the building, like flooring.

Solid timber for joinery products is generally supplied as ‘clear finish grade' but ‘paint grade' options are available and these are usually comprised of a composite material like MDF or glulam.

A large number of specialist suppliers and producers offer the consumer extensive choice of profiles for all of the most common and popular joinery products. Choice is in many cases, limited only by imagination.

Cabinetry is often associated with joinery and most typically includes, cupboards, benches and other similar ‘built in' furniture. Like joinery, cabinetry is generally specified as either paint or clear finish grade and naturally for clear finish grade timbers, appearance and surface finish are critical in achieving a successful application.

 

Panelling, Interior

Internal panelling, also known as appearance boards and linings, is not just a practical means of covering one or more walls and ceilings in a building, its inclusion in a room's interior design can generate looks that are both dramatic and stylish. Internal paneling comes as either solid natural timber paneling or as sheets of engineered wood products that provide a durable and hardwearing surface for areas subject to high impact. As they typically function as appearance products they generally have no structural requirements. This guide describes the variety of panelling products available and outlines the straightforward process of installing them.

Pergolas

Timber pergolas offer an attractive and economical way to create functional living and entertainment areas in the outdoors.  Pergolas designed with care can maximise both winter sunshine and summer shade, ensuring outdoor living is enjoyed all year round. With its natural look, durability and versatility there are few other materials that can match the advantages of timber in pergola construction.

Pergolas are typically constructed via a straightforward post and beam process, which can be attached to an existing building or form a free standing structure. A protective finishing coat will preserve the life of the pergola and a variety of paints and stains are available on the market to facilitate this.

 

Framing

Lightweight timber construction typically comprises framed and braced structures to which one or more types of cladding are applied. Framing configurations can range from the closely spaced light timbers commonly seen in stud frame construction to large, more widely spaced timbers. A timber framed building can be placed on a concrete slab or on posts/poles or bearers resting on piers/stumps supported on pad footings.

Used in houses or multi-residential dwellings, lightweight timber construction offers the flexibility of a wide range of cost effective design options.

When the timber comes from sustainable sources, this construction method can be environmentally advantageous as it combines timber's low embodied energy with its capacity to store carbon.

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