spore: profile
id: douglas-fir
spore_version: '0.2'
family: wood
name: Douglas fir (Pseudotsuga menziesii)
abbreviation: Douglas fir
role: Softwood conifer timber used for construction lumber, plywood and light aircraft wood structure
category: living
type: bio-grown-building-materials
summary: |
  Douglas fir (Pseudotsuga menziesii) is a softwood conifer from western North America. At 12% moisture content, Engineering ToolBox gives a density of 460 to 500 kg/m3 for Douglas-fir, and the USDA Wood Handbook gives a modulus of rupture of 85000 kPa for Coast Douglas-fir. Its strength and density vary by growth region, so the figures in this profile are kept side by side rather than merged.
best_for: Structural construction lumber and plywood where a light-to-medium softwood with a strength close to spruce is needed
weakest_at: Moderate decay resistance in damp service, and it is hard to work with hand tools (FAA)
identity:
  formula: 'Wood of Pseudotsuga menziesii: cellulose, lignin and hemicelluloses in a cellular structure'
  source: vt-dendro
  where: 'Title line: Pseudotsuga menziesii (Mirb.) Franco, family Pinaceae; common names list Douglas-fir'
tags:
  applications:
    - structures
properties:
  - benchmark: density
    label: Average dried weight
    value: 510
    unit: kg/m3
    scope: material
    conditions:
      basis: average dried weight as printed in the species data table
      moisture: no moisture condition stated on the page
    method: Printed on the Wood Database page as Average Dried Weight, with 32 lbs/ft3 shown alongside
    status: ground
    source: wood-database
    where: Species data table, Average Dried Weight row
  - benchmark: flexural_strength
    label: Modulus of rupture (bending strength)
    value: 86.2
    unit: MPa
    scope: material
    conditions:
      basis: value as printed on the Wood Database page, shown with 12,500 lbf/in2
      moisture: no moisture condition stated on the page
    method: Printed on the Wood Database species page under Physical and mechanical properties
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Modulus of Rupture
  - benchmark: elastic_modulus
    label: Elastic modulus
    value: 12.17
    unit: GPa
    scope: material
    conditions:
      basis: value as printed on the Wood Database page, shown with 1,765,000 lbf/in2
      moisture: no moisture condition stated on the page
    method: Printed on the Wood Database species page under Physical and mechanical properties
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Elastic Modulus
  - benchmark: crushing_strength
    label: Crushing strength (compression parallel to grain)
    value: 47.9
    unit: MPa
    scope: material
    conditions:
      basis: value as printed on the Wood Database page, shown with 6,950 lbf/in2
      moisture: no moisture condition stated on the page
    method: Printed on the Wood Database species page as Crushing Strength
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Crushing Strength
  - benchmark: janka_hardness
    label: Janka hardness
    value: 2760
    unit: 'N'
    scope: material
    conditions:
      basis: Janka hardness as printed, shown on the page as 620 lbf
      moisture: no moisture condition stated on the page
    method: Printed on the Wood Database species page as Janka Hardness
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Janka Hardness
  - benchmark: shrinkage_radial
    label: Radial shrinkage
    value: 4.5
    unit: '%'
    scope: material
    conditions:
      basis: shrinkage as printed; no condition stated on the page
    method: Printed on the Wood Database species page under Shrinkage
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Shrinkage (Radial)
  - benchmark: shrinkage_tangential
    label: Tangential shrinkage
    value: 7.3
    unit: '%'
    scope: material
    conditions:
      basis: shrinkage as printed; no condition stated on the page
    method: Printed on the Wood Database species page under Shrinkage
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Shrinkage (Tangential)
  - benchmark: shrinkage_volumetric
    label: Volumetric shrinkage
    value: 11.6
    unit: '%'
    scope: material
    conditions:
      basis: shrinkage as printed; no condition stated on the page
    method: Printed on the Wood Database species page under Shrinkage
    status: ground
    source: wood-database
    where: Physical and mechanical properties, Shrinkage (Volumetric)
  - benchmark: density
    label: Density, four Douglas-fir regions (range)
    value: 460
    value_high: 500
    bound: range
    unit: kg/m3
    scope: material
    conditions:
      moisture: '12% moisture content (table note: values for wood with 12% moisture content)'
      basis: Douglas-fir Coast, Interior West, Interior North and Interior South printed as one range
    method: Range printed in the Wood, Panel and Structural Timber Products table
    status: ground
    source: et-timber
    where: Clear Wood table, Douglas-fir row, Density column
  - benchmark: flexural_strength
    label: Fibre stress at elastic limit (modulus of rupture)
    value: 82
    value_high: 90
    bound: range
    unit: MPa
    scope: material
    conditions:
      moisture: 12% moisture content (table note)
      basis: Douglas-fir Coast, Interior West, Interior North and Interior South printed as one range
    method: Range printed in the Wood, Panel and Structural Timber Products table; the column is headed Fibre Stress at Elastic Limit (Modulus of Rupture)
    status: ground
    source: et-timber
    where: Clear Wood table, Douglas-fir row, Fibre Stress column
  - benchmark: elastic_modulus
    label: Modulus of elasticity (range)
    value: 10.3
    value_high: 13.4
    bound: range
    unit: GPa
    scope: material
    conditions:
      moisture: 12% moisture content (table note)
      basis: Douglas-fir regions printed as one range
    method: Range printed in the Wood, Panel and Structural Timber Products table
    status: ground
    source: et-timber
    where: Clear Wood table, Douglas-fir row, Modulus of Elasticity column
  - benchmark: compressive_strength_parallel_to_grain
    label: Compressive strength parallel to grain (range)
    value: 43.1
    value_high: 51.2
    bound: range
    unit: MPa
    scope: material
    conditions:
      moisture: 12% moisture content (table note)
      basis: Douglas-fir regions printed as one range
    method: Range printed in the Wood, Panel and Structural Timber Products table
    status: ground
    source: et-timber
    where: Clear Wood table, Douglas-fir row, Compressive Strength parallel to Grain column
  - benchmark: shear_strength_parallel_to_grain
    label: Shear strength parallel to grain (range)
    value: 7.8
    value_high: 10.4
    bound: range
    unit: MPa
    scope: material
    conditions:
      moisture: 12% moisture content (table note)
      basis: Douglas-fir regions printed as one range
    method: Range printed in the Wood, Panel and Structural Timber Products table
    status: ground
    source: et-timber
    where: Clear Wood table, Douglas-fir row, Shear Strength parallel to grain column
  - benchmark: density
    label: Density, seasoned and dry wood
    value: 530
    unit: kg/m3
    scope: material
    conditions:
      moisture: seasoned and dry wood (page wording)
      basis: single Douglas Fir value in the species table
    method: Printed in the Wood Species Densities table
    status: ground
    source: et-density
    where: Wood Species - Densities table, Douglas Fir row
  - benchmark: flexural_strength
    label: Modulus of rupture, Coast Douglas-fir
    value: 85000
    unit: kPa
    scope: material
    conditions:
      moisture: 12%
      basis: clear wood, Coast Douglas-fir (Oregon and Washington west of the Cascade summit), as printed in the metric table
    method: Printed in the Wood Handbook metric strength table, Douglas-fir Coast row, 12% moisture content line
    status: ground
    source: wh2010
    where: Table 5-3a (metric), Douglas-fir Coast, 12% row, modulus of rupture column
  - benchmark: elastic_modulus
    label: Modulus of elasticity, Coast Douglas-fir
    value: 13400
    unit: MPa
    scope: material
    conditions:
      moisture: 12%
      basis: clear wood, Coast Douglas-fir, as printed in the metric table
    method: Printed in the Wood Handbook metric strength table, Douglas-fir Coast row, 12% moisture content line
    status: ground
    source: wh2010
    where: Table 5-3a (metric), Douglas-fir Coast, 12% row, modulus of elasticity column
  - benchmark: compressive_strength_parallel_to_grain
    label: Compression parallel to grain, Coast Douglas-fir
    value: 49900
    unit: kPa
    scope: material
    conditions:
      moisture: 12%
      basis: clear wood, Coast Douglas-fir, as printed in the metric table; the table footnote calls compression parallel to grain the maximum crushing strength
    method: Printed in the Wood Handbook metric strength table, Douglas-fir Coast row, 12% moisture content line
    status: ground
    source: wh2010
    where: Table 5-3a (metric), Douglas-fir Coast, 12% row, compression parallel to grain column
  - benchmark: shear_strength_parallel_to_grain
    label: Shear strength parallel to grain, Coast Douglas-fir
    value: 7800
    unit: kPa
    scope: material
    conditions:
      moisture: 12%
      basis: clear wood, Coast Douglas-fir, as printed in the metric table
    method: Printed in the Wood Handbook metric strength table, Douglas-fir Coast row, 12% moisture content line
    status: ground
    source: wh2010
    where: Table 5-3a (metric), Douglas-fir Coast, 12% row, shear parallel to grain column
  - benchmark: specific_gravity
    label: Specific gravity, Coast Douglas-fir
    value: 0.48
    unit: '-'
    scope: material
    conditions:
      moisture: 12%
      basis: 'table footnote: specific gravity is based on ovendry weight and volume at 12% moisture content'
    method: Printed in the Wood Handbook metric strength table, Douglas-fir Coast row, 12% moisture content line
    status: ground
    source: wh2010
    where: Table 5-3a (metric), Douglas-fir Coast, 12% row, specific gravity column
corrosion:
  - environment: Damp service where decay fungi and wood-boring insects are present
    headline: Heartwood is moderately durable against decay but susceptible to insect attack.
    effect: The Wood Database rates Douglas-fir heartwood as moderately durable in regard to decay, but susceptible to insect attack. The page gives no exposure time or test method for this rating.
    rating: moderate
    conditions:
      basis: rating as printed on the species page; no exposure test described
    source: wood-database
    where: Decay and durability, Rot Resistance
risks:
  hazards:
    - text: 'Wood Database: Douglas-fir has been reported to cause skin irritation, nausea, giddiness and a runny nose, and splinters are more likely to become infected. Severe reactions are described as quite uncommon.'
      ghs: []
      source: wood-database
      where: Allergies/Toxicity
    - text: 'Wood Database allergy chart: Douglas-fir is listed as an irritant, with giddiness, runny nose, splinters going septic and nausea. The chart also states that all inhaled wood dust is hazardous to long-term health.'
      ghs: []
      source: wood-allergies
      where: Allergy and toxicity chart, Douglas-fir row, and the introduction text above it
    - text: IARC Monographs Volume 62 (1995) states that occupational exposure to wood dust is causally related to adenocarcinoma of the nasal cavities and paranasal sinuses. The classification applies to wood dust in general, not to Douglas-fir alone.
      ghs: []
      source: iarc-v62
      where: Classification statement on the monograph page
  failure_risks:
    - mode: Decay and insect attack in damp service
      trigger: Moisture in service together with decay fungi or wood-boring insects
      consequence: Loss of strength and service life; the sources we hold give no rate of loss
      severity: moderate
      source: wood-database
      where: Rot Resistance
    - mode: Splitting and splintering during fabrication
      trigger: Hand-working or machining Douglas-fir stock
      consequence: Split and splintered parts; the FAA notes large solid pieces are hard to inspect and should be avoided
      severity: low
      source: faa-ac43-13
      where: Table 1-1, Remarks column
  side_effects:
    - text: The wood has a distinct resinous odour when it is worked.
      affects: People working the wood
      source: wood-database
      where: Odor
  handling:
    - text: 'Wood Database allergy page: all woods produce fine dust when worked, so keep dust down when cutting or sanding.'
      source: wood-allergies
      where: Paragraph after the allergy chart introduction
    - text: 'FAA AC 43.13-1B: Douglas Fir is difficult to work with hand tools and gluing is satisfactory.'
      source: faa-ac43-13
      where: Table 1-1, Remarks column
  mitigations: []
uses:
  - application: structures
    device: Construction lumber, plywood, piles and engineered wood composites
    example: Douglas-fir is used mostly for building and construction purposes in the form of lumber, marine fendering, piles, plywood, and engineered wood composites.
    source: wh2010
    where: Chapter 2, Species Descriptions, Douglas-fir paragraph
  - application: structures
    device: Aircraft wood structure, as a substitute for spruce
    example: Douglas Fir exceeds spruce in strength; it may be used as a substitute for spruce in the same sizes or in slightly reduced sizes, providing the reductions are substantiated.
    source: faa-ac43-13
    where: Table 1-1, Douglas Fir row (printed as Pseudotsuga Taxifolia)
  - application: structures
    device: Railroad crossties, poles, mine timbers and fencing
    example: Considerable quantities are used for railroad crossties, cooperage stock, mine timbers, poles, and fencing.
    source: wh2010
    where: Chapter 2, Species Descriptions, Douglas-fir paragraph
supply:
  - subject: Douglas-fir timber (wood feedstock)
    producers: []
    critical_lists: []
    recycling: No recycling figure for Douglas-fir timber was found in the sources we hold.
    substitutes:
      - 'FAA AC 43.13-1B: Douglas Fir may be used as a substitute for spruce in the same sizes or in slightly reduced sizes, providing the reductions are substantiated.'
    source: vt-dendro
    where: 'Distribution paragraph: range from the Rocky Mountains to the Pacific coast and from Mexico to central British Columbia; production from the coast states of Oregon, Washington and California and the Rocky Mountain states'
media: []
documents:
  - title: 'Wood Database: Douglas Fir (softwood species profile)'
    type: database
    url: https://www.wood-database.com/douglas-fir/
  - title: 'Wood Handbook: Wood as an Engineering Material (FPL-GTR-190, 2010), copy hosted by California Air Resources Board'
    type: report
    url: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2014/capandtradeprf14/usfswoodhandbook2010.pdf
    year: 2010
  - title: FAA Advisory Circular AC 43.13-1B, Chapter 1 (copy hosted by RAANZ)
    type: standard
    url: https://raanz.org.nz/techproject/FAA%20AC43.13%20b/Chapter%2001.pdf
    year: 1998
  - title: 'IARC Monographs Volume 62: Wood Dust and Formaldehyde'
    type: report
    url: https://publications.iarc.who.int/80
    year: 1995
gaps:
  - No ageing or weathering data for Douglas-fir (greying, UV, moisture cycling) were found in a source we could open; the one search returned only other species.
  - No country-level production shares or current production volumes for Douglas-fir were found, so the supply entry lists feedstock regions only.
  - No flight, vacuum, radiation or thermal-cycling data for Douglas-fir were found, and no space application source was found.
  - Specific gravity of the other Douglas-fir regions was not recorded, because the Wood Database gives two unlabelled values (0.45, 0.51) and the Wood Handbook regions were not matched to them.
  - Shrinkage values in the Wood Handbook Table 4-3 are printed without an explicit unit on the page, so they were left out; the Wood Database shrinkage percentages are recorded instead.
  - Thermal conductivity, Poisson's ratio and fatigue strength for Douglas-fir were not recorded from a source we could open.
  - Moisture effects away from 12% moisture content were not recorded from a source we could open.
  - Combustion and fire behaviour for Douglas-fir were not found in a source we could open.
  - No UNS, EN or other standard grade designation applies to Douglas-fir timber, so none is listed.
sources:
  wood-database:
    title: Douglas Fir, Wood Database (softwood species profile)
    id: Wood Database, Douglas fir page
    url: https://www.wood-database.com/douglas-fir/
    kind: database
    license: cited, not reproduced
  wood-allergies:
    title: Wood Allergies and Toxicity, Wood Database
    id: Wood Database allergy and toxicity chart
    url: https://www.wood-database.com/wood-allergies-and-toxicity/
    kind: web
    license: cited, not reproduced
  et-timber:
    title: Wood, Panel and Structural Timber Products - Mechanical Properties (Engineering ToolBox)
    id: Engineering ToolBox, Clear Wood table
    url: https://www.engineeringtoolbox.com/timber-mechanical-properties-d_1789.html
    kind: web
    license: cited, not reproduced
  et-density:
    title: Density of Wood Species (Engineering ToolBox)
    id: Engineering ToolBox, Wood Species - Densities table
    url: https://www.engineeringtoolbox.com/wood-density-d_40.html
    kind: web
    license: cited, not reproduced
  wh2010:
    title: 'Wood Handbook: Wood as an Engineering Material, General Technical Report FPL-GTR-190 (2010 edition)'
    id: USDA Forest Service Forest Products Laboratory, FPL-GTR-190
    url: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2014/capandtradeprf14/usfswoodhandbook2010.pdf
    year: 2010
    kind: report
    license: US government publication
  vt-dendro:
    title: Pseudotsuga menziesii (Mirb.) Franco, Douglas-fir wood technology sheet (Virginia Tech Dendrology)
    id: Virginia Tech Dendrology, woodtech sheet
    url: https://dendro.cnre.vt.edu/DENDROLOGY/woodtech/pseudotsuga_menziesii.pdf
    kind: report
    license: cited, not reproduced
  faa-ac43-13:
    title: 'FAA Advisory Circular AC 43.13-1B, Chapter 1, Table 1-1: Selection and Properties of Aircraft Wood'
    id: AC 43.13-1B, dated 9/8/98
    url: https://raanz.org.nz/techproject/FAA%20AC43.13%20b/Chapter%2001.pdf
    year: 1998
    kind: standard
    license: US government publication
  iarc-v62:
    title: 'IARC Monographs Volume 62: Wood Dust and Formaldehyde (1995)'
    id: IARC Monographs Volume 62
    url: https://publications.iarc.who.int/80
    year: 1995
    kind: report
    license: IARC, cited
license: CC-BY-4.0
updated: '2026-11-02'
review:
  status: draft
  method: assistant
  checked_values: 19
  unreachable: 0
  caveats: 2
  note: Read by an AI assistant on 2026-11-02 from the cited pages and PDFs. Regional values are kept separate; the Wood Database averages are not merged with the regional tables.
story:
  recipe:
    line: Douglas-fir is wood, not a single compound. Its cell walls are built from cellulose, lignin and hemicelluloses, arranged in a cellular structure. The Wood Handbook gives this composition for all wood.
    parts:
      - name: Cellulose
        role: Long fibres that give the cell walls their tensile strength.
        source: wh2010
        where: Chapter 1, composition sentence
      - name: Lignin
        role: Binds the cellulose fibres together and stiffens the cell walls.
        source: wh2010
        where: Chapter 1, composition sentence
      - name: Hemicelluloses
        role: Matrix material between the cellulose fibres.
        source: wh2010
        where: Chapter 1, composition sentence
      - name: Cellular structure
        role: The hollow cells whose size and arrangement, with the component proportions, make a wood heavy or light, stiff or flexible, and hard or soft.
        source: wh2010
        where: Chapter 1, composition sentence
  risk_groups:
    - title: For people
      level: 1
      verdict: Dust and splinters are the reported hazards
      lead: The reported hazards are irritation from dust and splinters, and wood dust is classed as a cancer hazard in occupational exposure.
      points:
        - label: Dust
          line: The Wood Database allergy chart says all inhaled wood dust is hazardous to long-term health. IARC Volume 62 (1995) links occupational wood dust exposure to cancer of the nasal cavities and paranasal sinuses.
        - label: Skin and splinters
          line: The Wood Database reports skin irritation for Douglas-fir, and says splinters are more likely to become infected. Severe reactions are described as quite uncommon.
        - label: Odour
          line: The wood has a distinct resinous odour when worked.
    - title: If the wood is wet or infested
      level: 2
      verdict: Moderately durable against decay; susceptible to insects
      lead: Douglas-fir heartwood is rated moderately durable against decay and susceptible to insect attack.
      points:
        - label: Damp service
          line: Moisture with decay fungi or wood-boring insects is the main threat to the wood. The Wood Database rates the heartwood moderately durable, which gives no exposure time.
        - label: Splitting
          line: The FAA says Douglas Fir has some tendency to split and splinter during fabrication, and large solid pieces are hard to inspect.
  why: 'Douglas fir (Pseudotsuga menziesii) is a softwood from western North America. The Wood Handbook says it is used mostly for building and construction, and the FAA says it may be used as a substitute for spruce in some aircraft wood structures. It is in this collection as a structural timber benchmark, not as a space material: we found no flight data and no space-environment source for it.'
  uses:
    - where: Building and construction
      line: The Wood Handbook says Douglas-fir is used mostly for building and construction, as lumber, marine fendering, piles, plywood and engineered wood composites.
    - where: Aircraft wood structure
      line: FAA AC 43.13-1B Table 1-1 says Douglas Fir exceeds spruce in strength. It says the species may be used as a substitute for spruce in the same sizes, or in slightly reduced sizes, if the reductions are substantiated. The table prints the older name Pseudotsuga taxifolia.
    - where: Railroad ties, poles and fencing
      line: The Wood Handbook says considerable quantities are used for railroad crossties, cooperage stock, mine timbers, poles and fencing.
  can_do:
    - label: Density
      benchmark: density
      line: Engineering ToolBox gives 460 to 500 kg/m3 at 12% moisture content for the Douglas-fir regions. A separate table gives 530 kg/m3 for seasoned and dry wood, and the Wood Database gives 510 kg/m3 as average dried weight. The three figures use different moisture conditions, so they are shown side by side.
    - label: Bending strength
      benchmark: flexural_strength
      line: At 12% moisture content, Engineering ToolBox gives 82 to 90 MPa for fibre stress at elastic limit. The Wood Handbook gives 85000 kPa for Coast Douglas-fir, and the Wood Database gives 86.2 MPa modulus of rupture without a moisture condition.
    - label: Stiffness
      benchmark: elastic_modulus
      line: The Wood Handbook gives 13400 MPa modulus of elasticity for Coast Douglas-fir at 12% moisture content, and Engineering ToolBox gives a range of 10.3 to 13.4 GPa across the regions.
    - label: Hardness
      benchmark: janka_hardness
      line: The Wood Database gives a Janka hardness of 2,760 N for Douglas-fir.
    - label: Compression and shear
      benchmark: compressive_strength_parallel_to_grain
      line: At 12% moisture content, the Wood Handbook gives 49900 kPa compression parallel to grain for Coast Douglas-fir and 7800 kPa shear parallel to grain. Engineering ToolBox gives 43.1 to 51.2 MPa and 7.8 to 10.4 MPa across the regions.
  compare: Against spruce, the FAA table says Douglas Fir exceeds spruce in strength, but it is harder to work with hand tools and splits more readily. The sources give Douglas-fir values at different moisture contents and test regions, so this profile does not rank Douglas-fir numerically against other timbers. The compare rows below use the 12% moisture values from the regional tables.
  compare_rows:
    - label: Density at 12% moisture
      benchmark: density
    - label: Bending strength
      benchmark: flexural_strength
    - label: Stiffness
      benchmark: elastic_modulus
  handling:
    - Keep dust down when cutting or sanding. The Wood Database allergy page says all woods produce fine dust when worked.
    - Douglas-fir splits and splinters during fabrication, and it is hard to work with hand tools, according to the FAA.
    - Keep the wood dry where you can. Decay is the main risk in damp service, and the heartwood is only moderately durable.
  good_for:
    - Construction lumber, plywood and piles, where a strong softwood is needed (Wood Handbook).
    - Aircraft wood structure, where the FAA allows Douglas Fir as a spruce substitute if the reductions are substantiated.
  watch_out:
    - Moderate decay resistance and susceptibility to insect attack in damp service.
    - Splitting and splintering when worked, with large solid pieces hard to inspect.
    - Dust from the wood is a reported health hazard, and IARC classifies wood dust as carcinogenic to humans.
  verdict: A strong, widely used structural softwood. Keep it dry and control its dust and splinters.