Fir, Douglas | Pseudotsuga menziesii

Douglas fir is one of the world’s best-known timber species. Imported sawn timber products are readily available in Australia.

Other Names: Oregon Fir, Oregon Pine, Oregon, Green Douglas Fir, Blue Douglas Fir, Columbian Pine, Common Douglas, Coast Douglas Fir

Overview

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.

 

Properties

Shrinkage

Very Low Low Medium High Very High
Tangential:          
4.0
Radial: 2 - 3

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: F11 F8 F7 F5 F4
Seasoned: F17 F14 F11 F8 F7

Density per Standard

Unseasoned: 730 kg/m3
Seasoned: 550 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: 56
Modulus of Rupture - Seasoned: 90
Modulus of Elasticity - Unseasoned: 12
Modulus of Elasticity - Seasoned: 13
Maximum Crushing Strength - Unseasoned: 26
Maximum Crushing Strength - Seasoned: 55
Toughness - Unseasoned: Low - up to 15 Nm
Toughness - Seasoned: Low - up to 15 Nm
Hardness - Unseasoned: 2.1
Hardness - Seasoned: 3.1

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:
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

Description

Botanical Name: Pseudotsuga menziesii
Preferred Common Name: Fir, Douglas
Other Names: Oregon Fir, Oregon Pine, Oregon, Green Douglas Fir, Blue Douglas Fir, Columbian Pine, Common Douglas, Coast Douglas Fir
Species Type: Softwood

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, Veneer

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, VIC, TAS, NZ, North America, Europe

Readily Available

NSW, VIC, SA, TAS, QLD, WA, NT, NZ, North America, Europe

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.

Source of Timber

Plantation

Applications

  • 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.

  • 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.

Case Studies

  • Community Facilities, Kensington Gardens

    An award-winning building where timber is featured to spectacular effect as well as adding the warmth and character that make residents feel at home.

    Applications: Architectural Roof Trusses, Flooring, Internal Paneling,

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