Douglas Fir KD19
Grade
KD19 = kD19 / S-DRY
Standard framing/dimension-lumber condition sold as S-DRY or KD-HT; the basis for most building-code design values.
Values for the KD19 condition
Other Douglas Fir tempers and conditions
Douglas Fir is listed in 4 conditions; see the grade overview at Douglas Fir.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Douglas-fir laminated veneer lumber | Engineered veneer laminate for beams and headers: knots dispersed, so stiffness and strength are higher and far less variable than sawn lumber. | — | 55 | — | — | 0.13 W/m·K |
Unseasoned, MC above fibre saturation | Freshly sawn/wet-use lumber: heaviest, softest and lowest strength — use only where drying shrinkage is designed for. | — | 75 | — | — | 0.2 W/m·K |
KD19This page KD19 / S-DRY | Standard framing/dimension-lumber condition sold as S-DRY or KD-HT; the basis for most building-code design values. | — | 90 | 0.8 | — | 0.13 W/m·K |
KD12Default Kiln-dried to 12 % MC | Reference 12 % moisture condition used for published clear-wood properties and for interior joinery, flooring and millwork. | — | 105 | 1 | — | 0.12 W/m·K |
What is Douglas Fir KD19?
Douglas Fir KD19 is Douglas Fir in the KD19 grade — standard framing/dimension-lumber condition sold as S-DRY or KD-HT; the basis for most building-code design values. Douglas Fir KD19 has a tensile strength of 90 MPa (13.1 ksi), stronger than 73% of natural material grades. Elongation at break is 0.8% and the elastic modulus is 12.4 GPa (1.8 Msi). Douglas Fir KD19 has a density of 0.52 g/cm³ (0.0188 lb/in³), lighter than 72% of natural material grades. KD12 is the default condition FabDigit quotes; KD19 is available on request or by drawing note.
Limitations
- Limited service temperature — 65°C (149 °F), worse than 88% of natural material grades
- Limited ductility — 0.8%, worse than 81% of natural material grades
Douglas Fir KD19 properties
Typical room-temperature values for Douglas Fir KD19; 13 are specific to this condition. Other listed values are Douglas Fir reference data and may not represent this condition. Bars are the position among natural material grades.
Physical2
Douglas Fir KD19 has a density of 0.52 g/cm³ (0.0188 lb/in³), lighter than 72% of natural material grades.
Mechanical10
Douglas Fir KD19 has a tensile strength of 90 MPa (13.1 ksi), stronger than 73% of natural material grades. Elongation at break is 0.8% and the elastic modulus is 12.4 GPa (1.8 Msi).
Thermal5
Douglas Fir KD19 is rated for continuous service to 65°C (149 °F). It conducts heat at 0.13 W/m·K (0.0751 BTU/hr·ft·°F), worse than 57% of natural material grades. Thermal expansion is 4 µm/m·K (2.22 µin/in·°F).
Electrical2
Douglas Fir KD19 is an electrical insulator with a dielectric strength of 5 kV/mm (127 V/mil) and a resistivity of 1×10⁷ Ω·m.
Chemical & Environmental1
Corrosion resistance is good (55/100), better than 69% of natural material grades.
Sustainability4
Producing a kilogram of Douglas Fir KD19 takes about 10 MJ of energy and emits 0.35 kg of CO₂ — less than 56% of natural material grades. Typical recycled content is 5%.
Manufacturability2
Douglas Fir KD19's machinability is very good (78/100, worse than 57% of natural material grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Douglas Fir KD19
Is Douglas Fir easy to machine?
Saws, planes and routs easily with carbide tooling; hard latewood bands and resin cause tear-out and pitch build-up, so use sharp tools, high rake and periodic blade cleaning.
Can Douglas Fir be welded?
Not weldable — joined by nails, screws, split-ring/plate connectors, or PVA/PUR/resorcinol and phenolic adhesives (good bonding, but degrease resin-rich surfaces).
Can Douglas Fir be formed, bent or molded?
Poor steam-bending species (low bend ratio); shape by lamination of thin veneers/laminae as in glulam and LVL, allowing 3–5 % tangential shrinkage on drying.
What surface finishes work on Douglas Fir?
Sands well but raises grain and takes stain unevenly due to strong earlywood/latewood contrast — use conditioner or pigmented primer; heartwood resists preservative pressure treatment and usually needs incising.
Douglas Fir chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| celluloseoven-dry wood basis | 44 – 50 | 47 |
| hemicellulosemainly galactoglucomannan | 18 – 25 | 22 |
| ligninguaiacyl-type softwood lignin | 26 – 31 | 28 |
| extractives (resins, terpenes, phenolicshigher in heartwood; causes resin pockets | 2 – 6 | 3.5 |
| ash (inorganics) | 0.2 – 0.6 | 0.3 |
Douglas Fir KD19 — frequently asked
What is Douglas Fir KD19 used for?
Douglas Fir KD19 is typically used for structural framing, glulam beams, plywood face veneer, marine spars and heavy timber construction. In short: stiffest common framing softwood; base species for glulam and LVL; poor steam-bending species.
What is the tensile strength of Douglas Fir KD19?
Douglas Fir KD19 has a typical tensile strength of 90 MPa (13.1 ksi) — stronger than 73% of natural material grades. Strength varies by condition: see the 4 listed tempers.
Is Douglas Fir KD19 easy to machine?
Yes — machinability is rated very good (78/100, worse than 57% of natural material grades). Saws, planes and routs easily with carbide tooling; hard latewood bands and resin cause tear-out and pitch build-up, so use sharp tools, high rake and periodic blade cleaning.
Can Douglas Fir KD19 be welded?
Not weldable — joined by nails, screws, split-ring/plate connectors, or PVA/PUR/resorcinol and phenolic adhesives (good bonding, but degrease resin-rich surfaces).
What surface finishes work on Douglas Fir KD19?
Sands well but raises grain and takes stain unevenly due to strong earlywood/latewood contrast — use conditioner or pigmented primer; heartwood resists preservative pressure treatment and usually needs incising.
Can Douglas Fir KD19 be formed, bent or molded?
Poor steam-bending species (low bend ratio); shape by lamination of thin veneers/laminae as in glulam and LVL, allowing 3–5 % tangential shrinkage on drying.
What is the maximum service temperature of Douglas Fir KD19?
Douglas Fir KD19 is rated for continuous use to about 65°C (149 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Wood Handbook — Wood as an Engineering Material (FPL-GTR-190) — USDA Forest Products Laboratory (2010)
- ASTM D2555 — Establishing Clear Wood Strength Values — ASTM International (2017)
- ASTM D143 — Standard Test Methods for Small Clear Specimens of Timber — ASTM International (2022)
- EN 13556 — Nomenclature of timbers used in Europe (code PSMe) — CEN (2003)
- LVL Product Guide / Design Properties — APA – The Engineered Wood Association (2021)
- Inventory of Carbon & Energy (ICE) v3 — sawn softwood — Circular Ecology (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.