Choosing the Right Timber for the Job

You now know what density means, how hardness is measured, what stiffness and strength tell you, how durability classes work, what rot resistance depends on, how workability varies, what extractives do, which species are toxic, and how much each one moves. This final guide in Track 3 brings all of that together into the question that matters most: which timber should I actually use?

Choosing a species is never about optimising a single property. It's about balancing competing requirements against the realities of the application, the environment, the budget, and the supply chain. Every project involves trade-offs, and the best decisions come from understanding what those trade-offs are. This guide gives you a framework for thinking through species selection systematically — and then applies it to the most common real-world scenarios.

The Selection Framework

Every species selection decision can be broken down into the same set of questions. Work through them in order:

1. Where will the timber be used?

This is the single most important question. The use environment determines which properties are critical:

• Interior, heated, dry — Stability matters most. Durability is irrelevant (no decay risk indoors). Appearance, workability, and hardness dominate.
• Interior, unheated — Stability still matters, but wider humidity swings increase movement. Condensation risk may introduce mild decay concerns.
• Exterior, above ground — Durability becomes critical. Stability matters for dimensional components (windows, doors). UV resistance affects appearance.
• Exterior, ground contact — Maximum durability required. Only Class 1–2 species or preservative-treated timber should be used.
• Exterior, marine / freshwater — Durability, stability, and resistance to waterlogging. A very demanding environment.
• Structural — Strength (MOR), stiffness (MOE), and grading class are primary. Appearance is secondary.

2. What loads will it carry?

• No structural load (panelling, trim, furniture) — Strength is rarely the limiting factor. Choose for appearance, workability, and stability.
• Light structural load (shelving, cabinet frames) — Moderate stiffness needed. Most species are adequate.
• Heavy structural load (beams, joists, rafters) — Strength class and stiffness are primary selection criteria. Use graded structural timber.
• Impact loads (flooring, workbenches, tool handles) — Hardness (Janka) and toughness are critical.

3. What are the appearance requirements?

• Natural finish / visible grain — Colour, grain pattern, figure, and finishing quality matter. Choose species with the desired visual character.
• Painted — Appearance of the raw wood is less important. Choose for stability, workability, and paint adhesion.
• Hidden — Appearance is irrelevant. Choose for performance and cost.

4. What is the budget?

• Premium — Teak, walnut, cherry, quarter-sawn oak, mahogany alternatives
• Mid-range — Oak, ash, sapele, Douglas fir, larch
• Economy — Pine, spruce, poplar, engineered products Cost includes not just the timber price but also:
• Waste rate — species with defects, sapwood to reject, or difficult grain increase waste
• Machining cost — difficult species take longer to process
• Finishing cost — some species require more surface preparation or specialised finishes
• Maintenance cost — non-durable species in exterior use require ongoing treatment

5. Are there specific constraints?

• Health — Working with allergenic species (cocobolo, Western Red Cedar, mansonia) requires additional safety measures and may be inappropriate for some workshops
• Sustainability / legality — Some species require CITES documentation or FSC certification. Some are effectively unavailable due to trade restrictions.
• Availability — Not every species is available in every region, in every dimension, or at every quality level
• Tradition / specification — Some projects require specific species (heritage repairs, instrument making, cooperage)

---

The Property Trade-Off Matrix

No species is perfect at everything. Here are the most common trade-offs:

Durability vs Workability

The most durable species tend to be dense, hard, and difficult to machine:

• Ipe — Class 1 durability, but extremely hard, oily, and difficult to work
• Teak — Class 1 durability with moderate workability, but oily (gluing issues)
• Oak — Class 2 durability with good workability, but high T/R ratio

Stability vs Cost

The most stable species tend to be expensive:

• Teak — excellent stability, but premium price
• Mahogany — excellent stability, but restricted supply and high cost
• Western Red Cedar — good stability and moderate cost, but low strength and hardness

Hardness vs Weight

Harder species are denser and heavier:

• A hardwood floor in ipe (Janka ~15,620 N) is extremely durable but weighs roughly 1,000 kg/m³
• A floor in pine (Janka ~3,510 N) is much lighter but dents easily

Strength vs Stability

Some of the strongest species are also the least stable:

• Beech — very strong and hard, but among the least stable common species
• Hickory — extremely tough, but high total shrinkage

---

Application Guides

Here's how the framework applies to common scenarios. Each recommendation explains why the species suits the application, linking back to the specific properties covered in this track.

Exterior Cladding

Requirements: Durability (Class 3 minimum, ideally Class 2+), stability (minimal cupping and warping), acceptable appearance weathering, reasonable cost.

**Species**	**Durability**	**Stability**	**Notes**
**Western Red Cedar**	Class 2	Excellent	The classic choice. Low density, low shrinkage, good natural durability. Weathers to silver-grey. Allergenic dust — protect during installation.
**European Larch**	Class 3	Moderate	Harder and stronger than cedar. Resinous — resin bleed possible. Good value. Heartwood only.
**Siberian Larch**	Class 3	Moderate	Tighter growth rings than European larch. Denser. Good cladding species.
**Thermally modified pine/spruce**	Class 2–3	Good	Improved durability and stability through thermal treatment. Reduced strength. Increasingly popular.
**Accoya (acetylated radiata pine)**	Class 1	Excellent	Near-zero movement. Class 1 durability. Premium cost. The highest-performing option.

Exterior Decking

Requirements: Durability (Class 2 minimum for ground-proximity use), hardness (foot traffic, furniture), slip resistance, stability.

**Species**	**Durability**	**Janka (N)**	**Notes**
**Ipe**	Class 1	\~15,620	Extremely durable and hard. Difficult to fasten (pre-drill everything). Oily — difficult to finish. Premium cost. The benchmark.
**Cumaru**	Class 1	\~14,500	Similar performance to ipe at lower cost. Very dense.
**Teak**	Class 1	\~4,740	Excellent durability and stability. Softer than ipe but still adequate. Very expensive. The luxury choice.
**European Oak**	Class 2	\~5,700	Good durability. Tannin staining on adjacent surfaces. Iron staining with steel fasteners — use stainless.
**Treated softwood (UC3/UC4)**	Class 2–3 (treated)	\~3,500	Budget option. Adequate durability if properly treated. Lower hardness — will dent and mark. Requires ongoing maintenance.

### Fine Furniture (Interior) **Requirements:** Appearance, workability, stability, finishing quality. Durability not required.

**Species**	**Stability**	**Workability**	**Notes**
**Black Walnut**	Good (T/R 1.4)	Excellent	Beautiful colour and grain. Low T/R ratio — very even movement. Easy to work. Takes finish superbly. The furniture maker's first choice in many traditions.
**American Cherry**	Good (T/R 1.9)	Excellent	Beautiful warm tone that deepens with age. Easy to work. Moderate stability. UV colour change is dramatic — embrace it or protect against it.
**European Oak (quarter-sawn)**	Good when QS	Good	Classic appearance with medullary ray figure. Must be quarter-sawn for best stability. Iron staining risk — use stainless steel hardware.
**Sapele**	Good (T/R 1.5)	Moderate	Ribbon stripe figure in quarter-sawn boards. Interlocked grain requires sharp tools and careful planing. Good mahogany alternative.
**European Ash**	Moderate (T/R 1.6)	Good	Strong, elastic, with bold grain. Excellent for steam bending. Lighter colour suits Scandinavian and contemporary styles.

### Structural Framing **Requirements:** Strength class, stiffness, availability in structural dimensions, cost.

**Species**	**Typical strength class**	**MOE (GPa)**	**Notes**
**Spruce / Pine (whitewood)**	C16–C24	8–11	The workhorse of structural framing. Widely available, well understood, and cost-effective. Graded to EN 338.
**Douglas Fir**	C24–C30	11–13	Stronger and stiffer than whitewood. Available in larger dimensions. Good for beams and posts.
**European Oak**	D30–D40	10–12	Traditional framing timber. Extremely durable. Beautiful exposed structural work. Premium cost.
**Glulam (spruce/pine)**	GL24–GL32+	11–14	Engineered beams. Longer spans, more consistent properties, and available in dimensions beyond what solid timber provides.

### Flooring (Interior) **Requirements:** Hardness (Janka), stability, appearance, finishing quality.

**Species**	**Janka (N)**	**Stability**	**Notes**
**European Oak**	\~5,700	Moderate–Poor (PS) / Good (QS)	The most popular hardwood floor. Good hardness. Quarter-sawn boards are dramatically more stable. Wide plank floors need careful acclimation.
**American White Oak**	\~6,000	Moderate	Slightly harder than European oak. Excellent floor species. Similar tannin and iron staining considerations.
**Hard Maple**	\~6,400	Poor	Very hard. Classic gym and commercial floor. Light colour. High movement — needs tight environmental control.
**European Ash**	\~5,900	Moderate	Good hardness. Bold grain. Similar performance to oak with a lighter aesthetic.
**Douglas Fir**	\~3,160	Moderate	Softer — will dent. But warm character and honey colour with age. Suits residential settings where patina is welcomed.
**Pine**	\~3,510	Moderate	Budget option. Soft — dents and marks easily. Traditional in period properties. Beautiful aged character.

Windows and External Joinery

Requirements: Durability (Class 2+ or treated to Class 2+), stability (tight tolerances), machinability, paint/finish adhesion.

**Species**	**Durability**	**Stability**	**Notes**
**Accoya**	Class 1	Excellent	The gold standard for modern timber windows. Near-zero movement. Superb paint retention. Premium cost but dramatically reduced maintenance.
**European Oak**	Class 2	Moderate	Traditional choice. Durable. Tannin can bleed through paint — use isolation primer. Higher movement than Accoya.
**Sapele**	Class 2–3	Good	Good stability. Machines well. Increasingly used as a mahogany replacement in joinery.
**Treated softwood (modified)**	Class 2–3	Good	Thermally modified pine/spruce offers improved durability and stability at moderate cost.

### Boat Building **Requirements:** Durability (salt/fresh water), stability, strength-to-weight ratio, bending properties, glueability. - **Teak** — Decks and trim. Excellent durability and stability. Oily — epoxy adhesive required. - **Honduras Mahogany** — Planking and interiors. Exceptional stability (T/R 1.4). Now rare; sapele and utile are common substitutes. - **White Oak** — Frames and structural members. Strong, durable, and steam-bends well. Tyloses block water penetration. - **Western Red Cedar** — Planking (strip-built canoes and kayaks). Light, stable, rot-resistant. - **Douglas Fir / Sitka Spruce** — Spars and structural members. High strength-to-weight ratio. - **Marine plywood** — Hull panels in modern construction. Stable, strong, and predictable. ### Outdoor Furniture **Requirements:** Durability (Class 2+), stability, appearance (often unfinished), comfort (not too hot or cold to touch). - **Teak** — The classic. Durable, stable, weathers beautifully to silver. Expensive. - **Iroko** — A practical teak alternative. Durable, stable, more affordable. Allergenic dust — protection during making. - **European Oak** — Durable enough for above-ground exterior. Use stainless steel fasteners. - **Accoya** — Near-zero movement and Class 1 durability. Paintable or stainable. - **Western Red Cedar** — Light, stable, durable. Best for lighter furniture where strength isn't critical. --- ## The Decision Checklist Before finalising a species for any project, run through this checklist: - [ ] **Environment**: Is the durability class appropriate for the use class? - [ ] **Load**: Is the strength and stiffness adequate for the structural demands? - [ ] **Movement**: Is the species stable enough for the design, or have I designed to accommodate movement? - [ ] **Hardness**: Is the Janka rating appropriate for the wear the surface will receive? - [ ] **Workability**: Can I machine this species with my equipment and skills? - [ ] **Finishing**: Are there known finishing issues (oil, tannin, resin) and do I know how to manage them? - [ ] **Health**: Am I aware of the toxicity risks and do I have appropriate protection? - [ ] **Fasteners**: Do I need stainless steel or non-ferrous fasteners (tannin-rich species)? - [ ] **Budget**: Does the species fit the project budget including waste, machining, and finishing costs? - [ ] **Availability**: Can I source the species in the grade, dimension, and quantity I need? - [ ] **Sustainability**: Is the species legally and sustainably sourced? Do I need CITES documentation? --- ## When There Is No Perfect Species In most real projects, no single species ticks every box. The skill is in deciding which compromises are acceptable: - A garden bench needs durability *and* comfort — teak delivers both, but at a price. Treated softwood is affordable but won't last as long and feels different. - A wide dining table needs stability *and* appearance — walnut is ideal, but expensive. Oak is beautiful but moves more. The answer might be quarter-sawn oak, or an engineered substrate with an oak veneer. - A workshop bench needs hardness *and* weight *and* cost-effectiveness — beech is hard, heavy, and affordable, but moves a lot. Maple is harder but more expensive. The compromise might be beech with a well-designed base that tolerates seasonal movement. The right answer depends on the project's priorities. **There is no universally "best" timber — only the best timber for the job.**

---

How Timber Logic Helps

This is exactly what the Timber Logic species database is designed for. Every species page brings together:

• Density and Janka hardness — Guide 1 and Guide 2
• MOE and MOR — Guide 3
• Durability class — Guide 4
• Rot resistance details — Guide 5
• Workability notes — Guide 6
• Extractive profile — Guide 7
• Health risks — Guide 8
• Shrinkage values and stability rating — Guide 9 All on one page, cross-linked to these guides, with calculators for movement, quantity, and cost. The goal is to give you everything you need to make an informed species decision — quickly, in one place, backed by the science.

---

Media and Image Recommendations

1. Flowchart: species selection decision tree
   • A visual decision tree starting with "Where will the timber be used?" and branching through durability, load, appearance, and budget to arrive at recommended species
2. Comparison infographic: five common species across all properties
   • Radar/spider charts showing oak, walnut, pine, teak, and beech rated across density, hardness, stiffness, durability, stability, and workability
3. Photo grid: application examples
   • Six photos showing the recommended species in each application: cedar cladding, ipe decking, walnut table, oak floor, Accoya windows, teak garden bench
4. Table graphic: the decision checklist
   • Clean, printable version of the checklist above
5. Diagram: trade-off visualisation
   • A visual showing how increasing durability typically comes with decreasing workability, and how stability vs cost creates a clear gradient

---

The Key Idea

---

What's Next: Track 3 Complete

You've now completed Track 3 — Timber Properties. You understand how species differ across every measurable property, and you have a framework for turning that knowledge into real-world decisions. Track 4 — Processing takes the next step: how timber goes from the log to usable material. Sawing methods, drying (kiln and air), grading, preservative treatment, and modification. The properties you've learned in this track determine how timber responds to every stage of processing — and processing, in turn, determines the quality of the material you work with.

🔗 Knowledge Network

Species Pages

• Western Red Cedar — cladding, outdoor furniture, excellent stability
• Teak — decking, outdoor furniture, boat building, joinery benchmark
• European Oak — decking, flooring, structural framing, joinery, cooperage
• Ipe — decking benchmark, extreme hardness and durability
• Black Walnut — fine furniture, excellent T/R ratio
• American Cherry — fine furniture, dramatic colour change
• Sapele — joinery and furniture, mahogany alternative
• European Ash — furniture, flooring, steam bending
• European Beech — workshop benches, high hardness, poor stability
• Hard Maple — flooring, high hardness, poor stability
• Douglas Fir — structural framing, flooring
• Pine / Spruce — structural framing, economy flooring
• European Larch — cladding
• Iroko — outdoor furniture, teak alternative, allergenic dust
• Accoya — windows, cladding, near-zero movement, Class 1 durability
• Cocobolo — health risk flagged for workshop use
• Mansonia — health risk flagged, cardiac risk

Glossary Terms

• Janka Hardness
• MOE (Modulus of Elasticity)
• MOR (Modulus of Rupture)
• Durability Class
• Use Class
• Strength Class
• T/R Ratio
• CITES
• FSC
• Glulam
• Accoya
• Thermal Modification

Calculators

• Movement Calculator
• Quantity Calculator

Related Guides

• Fact-Check Report — Guide 10: Choosing the Right Timber for the Job