Softwoods
Softwoods are conifer timbers — pine, fir, spruce, cedar, redwood — grown fast on plantations and sawn into the dimension lumber, plywood veneer and crating stock that most of the built world is made of. They run 0.35–0.55 g/cm³ with a bending modulus of 8–13 GPa, so they are lighter and less stiff than hardwoods but stronger for their weight, and they cut, nail and screw quickly. Knots, pitch and wide growth rings are normal; structural use relies on a stamped grade, not a datasheet value.
Popular softwood grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Douglas Fir | — | 105 | 0.48 | Very good | — | Strongest common softwood; beams, jigs, formwork |
| Southern Yellow Pine | — | 80 | 0.62 | Very good | — | Pressure-treated lumber, pallets, decking |
| SPF | — | 22 | 0.42 | Excellent | — | Framing, crates and blocking at lowest cost |
| Radiata Pine | — | 90 | 0.48 | Excellent | — | Clear plantation pine for mouldings and patterns |
| Cedar | — | 55 | 0.37 | Excellent | — | Rot-resistant cladding, fencing, outdoor furniture |
| Redwood | — | 70 | 0.42 | Excellent | — | Stable outdoor boards that resist decay |
All 6 softwood grades
Choose softwood for
Framing, joists and formwork; export crates, pallets, skids and shipping blocks; low-cost jigs, fixtures and foundry patterns; mouldings, doors and painted joinery; fences, decks, cladding and outdoor furniture in Cedar or Redwood; any part where weight and cost matter more than hardness or figure.
Look elsewhere when
The surface will be handled, walked on or knocked (a hardwood such as Hard Maple or White Oak — softwoods dent at a few MPa), the panel must stay flat (Plywood or MDF), the span is long and deflection governs (LVL or Glulam are graded and 30–50 % stiffer than sawn stock), the part is visible and must be stain-free (softwood blotches and bleeds pitch), or it sits in wet ground without treatment (only Cedar and Redwood heartwood last, and not indefinitely).
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Softwood by application
- Crates, pallets and skids
- SPF and Southern Yellow Pine, heat-treated and stamped to ISPM 15 for export; Douglas Fir for heavy machinery skids and blocking.
- Structural framing and formwork
- Douglas Fir or Southern Yellow Pine to a stamped visual or machine-stress-rated grade; SPF for light framing. The grade, not the species, sets the allowable stress.
- Patterns, jigs and mock-ups
- Radiata Pine or clear Douglas Fir — straight-grained, cheap to machine and easy to shape and fill; seal before use so the pattern does not move.
- Outdoor and garden
- Cedar and Redwood heartwood untreated, or pressure-treated Southern Yellow Pine and Radiata Pine for ground contact; stainless or hot-dip galvanized fasteners in all of them.
Working with softwood
- Cutting and machining
- Softwoods cut faster than hardwoods but tear more: the soft earlywood crushes ahead of a dull edge, so use sharp tooling, a higher feed per tooth (0.2–0.4 mm) and down-cut or compression spirals for a clean top face. Knots are hard and can throw a cutter; pitch pockets gum tools and need solvent cleaning. Tolerance of ±0.3 mm is realistic on solid softwood because the material itself moves that much.
- Joining and fastening
- Nails and screws hold well in Douglas Fir and Southern Yellow Pine, less in SPF and poorly in Cedar and Redwood; pre-drill within 50 mm of an end to stop splitting. PVA glue bonds all of them, but resinous pine needs freshly planed faces. Cedar and Redwood tannins corrode plain steel and stain black around it — use stainless, silicon bronze or hot-dip galvanized fasteners outdoors.
- Finishing
- Softwood blotches under stain, bleeds pitch through paint at knots and weathers gray outside within a year. Prime knots with a shellac-based sealer before painting, use a gel stain or a conditioner for an even colour, and expect Cedar and Redwood to need an oil or a UV-blocking finish every 1–2 years if colour matters. Left bare, Cedar and Redwood last decades but turn silver-gray.
- Movement and moisture
- Softwoods shrink about 7 % tangentially from green to oven-dry (Cedar and Redwood about 5 %), so kiln-dried stock at 15–19 % moisture content still moves as it dries to 8–12 % in service — a 90 mm framing member loses 1–2 mm of width. Buy kiln-dried, stack and sticker it flat, acclimatize a week before machining, and keep end grain sealed and off wet concrete. Pressure treatment adds water; let treated lumber dry before painting.
Other natural material series
Softwoods — frequently asked
What is softwood?
Softwoods are conifer timbers — pine, fir, spruce, cedar, redwood — grown fast on plantations and sawn into the dimension lumber, plywood veneer and crating stock that most of the built world is made of. They run 0.35–0.55 g/cm³ with a bending modulus of 8–13 GPa, so they are lighter and less stiff than hardwoods but stronger for their weight, and they cut, nail and screw quickly. Knots, pitch and wide growth rings are normal; structural use relies on a stamped grade, not a datasheet value.
Which grade of softwood should I use?
Douglas Fir when strength and stiffness matter: the highest modulus of the common softwoods (about 13 GPa) for beams, formwork, jigs and heavy crates. Southern Yellow Pine is nearly as strong, denser and more resinous, and the standard for pressure-treated lumber and pallets. SPF (spruce-pine-fir) is the light, cheap framing and packaging stock — fine for crates, blocking and studs, not for anything that carries a calculated load without a grade stamp. Radiata Pine is the clear, knot-free plantation pine for mouldings, furniture parts and patterns, and it takes treatment well. Cedar and Redwood are the naturally rot-resistant species for fencing, cladding, decking and outdoor furniture, soft and light enough to split and dent easily.
Which grade of softwood is easiest to machine?
SPF (machinability excellent, 95/100), then Cedar (90/100).
Douglas fir or southern yellow pine?
Both are the strong structural softwoods, graded to similar allowable stresses. Douglas Fir is stiffer for its weight (about 13 GPa modulus at 0.50 g/cm³), straighter and more stable, and is the western framing and beam species. Southern Yellow Pine is denser and harder (Janka 3–4 kN versus 2.9 kN), more resinous, moves more, and accepts pressure treatment far better — which is why treated decking and posts are pine. Choose by availability in your region and by whether it needs treating.
What does the grade stamp on softwood lumber mean?
It certifies species group, moisture content at surfacing (S-DRY or KD is 19 % or less) and a strength grade — Select Structural, No. 1, No. 2 or a machine-stress-rated value such as 2400f-1.8E — assigned by an accredited agency. Design values in NDS or Eurocode 5 are keyed to that grade, so a structural drawing should call out the grade and species group, not a species alone. Ungraded shop lumber has no assigned strength and belongs in jigs and crates, not in beams.