Afzelia Wooden windows – Class 1 Durability, the Hardest in our Range

We manufacture bespoke Afzelia wooden windows at SM WOOD, with a longer lead time compared to European species. Afzelia originates from tropical Africa and delivers 835 kg/m³ density, 8230 N Janka hardness, and pure Natural Durability Class 1 – the hardest and heaviest species in our range. It is a step above merbau in durability and hardness, with the same thermal penalty: λ ~0.19 W/m·K.

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Density 835 kg/m³

Heavy & solid

Janka 8230 N

Hardest in our range

Durability Class 1

Pure – no restrictions

Pure Class 1 Durability, Maximum Hardness

Afzelia (Afzelia africana, Afzelia bipindensis, Afzelia quanzensis) reaches 835 kg/m³ and 8230 N Janka, with Natural Durability Class 1 – the hardest and heaviest species in our range. It is a step above merbau in durability and hardness, with the same thermal penalty: λ ~0.19 W/m·K.

Two things to know from the start: the interlocked grain makes processing more difficult and expensive. The IUCN has listed Afzelia africana as Vulnerable and Afzelia bipindensis as Near Threatened – FSC availability and provenance should be discussed at the time of ordering. Not in stock; available to order with a longer lead time and premium pricing.

Technical Data

Property	Value
Density	835 kg/m³
Janka Hardness	8230 N
Bending Strength	109 MPa
Modulus of Elasticity	11.75 GPa
Compressive Strength	66 MPa
Radial Shrinkage	3.3 %
Tangential Shrinkage	4.8 %
Volumetric Shrinkage	8.2 %
Thermal Conductivity (λ)	~0.19 W/m·K
Natural Durability Class	1 (very durable)

What these figures mean for joinery: The density of 835 kg/m³ is the highest in our range – hardware and hinges must be dimensioned accordingly. Janka 8230 N means Afzelia does not show visible marks even after decades of heavy use. Radial shrinkage 3.3% and tangential 4.8% are better than oak. λ ~0.19 W/m·K is among the highest in the compared range; for strict nZEB projects, Afzelia is not the optimal thermal choice. Class 1 durability with resistance to rot, termites, and marine borers – plus documented resistance to acids and bases.

Performance in Windows

Afzelia brings maximum hardness and full Class 1 durability to demanding exposures.

1

Thermal

λ ~0.19 W/m·K – among the highest in the compared range. The Uf-value of an Afzelia frame is higher than spruce or meranti. For nZEB projects with Uw <=1.0 W/m²K, Afzelia on IV92/D92 meets the requirement – but at the upper limit. Exact Uf/Uw values are calculated on request.

2

Hardness

8230 N Janka – the highest in our range. For high-traffic entrance doors or windows with sills subjected to repeated mechanical wear, Afzelia offers the maximum resistance available.

3

Durability

Pure Class 1. No other species in our standard range (excluding Accoya) reaches this level. In extreme exposures – marine climates, high UV, chemicals – Afzelia shows the best possible natural behaviour.

Performance Over Time

Afzelia’s natural durability gives decades of stable performance, even in aggressive environments.

Longevity

Untreated Afzelia withstands tropical outdoor conditions for decades. In the Romanian climate, with a correct industrial finish, Long-term performance depends on correct finishing and maintenance.

Maintenance

With at least 4 layers of Remmers Aqua Stopp applied in the factory: maintenance inspection at 10 years, with a superior tolerance margin for delayed maintenance compared to any European species.

Chemical Resistance

Afzelia resists acids and bases – a rare property relevant for industrial spaces, laboratories, or buildings with corrosive vapours. No other species in our range offers this documentation.

Processing allergies: the Afzelia genus can cause skin, eye, and respiratory irritation during processing. Our team works with protective equipment. The client is not exposed to the finished, coated product.

Advantages of Afzelia

Advantages

Janka 8230 N – the hardest in our range, exceeding merbau and ash
Pure Natural Durability Class 1 – without the Class 1-2 restrictions of merbau
Good dimensional stability: tangential shrinkage 4.8% vs 8.4% for oak
Resistance to acids and bases – documented advantage in chemically exposed environments
Reddish-gold appearance with elegant ageing under translucent stains

Disadvantages

λ ~0.19 W/m·K – among the highest in the compared range, a thermal penalty
Density 835 kg/m³ – hardware must be specifically dimensioned
Interlocked grain – more difficult and expensive to process
IUCN Vulnerable/Near Threatened – FSC mandatory for responsible orders
High cost, longer lead time compared to European species

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Comparison with Other Essences

How Afzelia compares with the main alternatives in our joinery range.

Afzelia vs Merbau

Afzelia (835 kg/m³, 8230 N) is slightly heavier, harder, and has purer durability than merbau (815 kg/m³, 7620 N, Class 1-2). λ is identical (~0.19). Afzelia does not bleed red tannin onto adjacent surfaces. The practical difference is small – the choice depends on availability and aesthetic preference.

Afzelia vs Oak

Afzelia wins decisively on hardness (8230 vs 4980 N) and durability (Class 1 vs Class 2). Oak wins on thermal performance (λ 0.18 vs 0.19 – a small difference), availability and cost. For standard projects, oak is sufficient; for extreme traffic or difficult exposures, Afzelia makes sense.

Afzelia vs Accoya

Accoya (512 kg/m³, λ ~0.11) wins decisively on thermal performance. Afzelia wins on raw hardness (8230 vs 4100 N) and availability on more profiles. For nZEB projects with difficult exposure, Accoya is thermally more suitable; for extreme-traffic doors where maximum hardness is key, Afzelia is the choice.

Appearance and Colour

Heartwood is gold to reddish-brown, darkening to a deeper golden-brown with age. The interlocked grain produces light reflections distinct from straight-grained species. Under translucent stains: a warm reddish-gold tone with a depth of colour that intensifies over time. Under opaque RAL paint: visually identical to any other wood – choosing Afzelia for an opaque finish is purely technical.

Availability & SM WOOD Execution

Key Details

Available to order – longer lead time compared to European species. Origin from tropical Africa (Mozambique, East and Central Africa).
Premium pricing – lead times and availability confirmed at the quoting stage.
FSC mandatory – Afzelia africana listed as IUCN Vulnerable; Afzelia bipindensis IUCN Near Threatened. Responsible orders require FSC certification.
Standard 5-year SM WOOD warranty; maintenance inspection at 10 years.

Contact us for Afzelia availability

Price varies with profile, opening size and configuration – request a free quotation. For B2B projects we provide Ud, Uf, Ug and PHPP data on request. FSC certification is discussed at the quoting stage.

When Afzelia is NOT the right choice

Afzelia is the right choice when

The entrance door or window has extreme exposure and the client desires Natural Durability Class 1 without chemical modification
Heavy traffic on thresholds and sills requires the highest hardness in the range
The environment has specific chemical exposure (vapours, weak acids) - resistance to acids and bases is a real property
The client accepts the higher cost compared to European species and the longer lead time
The reddish-gold aesthetic with natural ageing is part of the project requirement

Afzelia is not recommended when

The project has strict PHPP requirements or is nZEB aiming for the lowest possible Uw – λ 0.19 W/m·K is a thermal penalty.
Budget is the main factor – European species meet requirements at a much lower cost.
Short execution time – Afzelia is available to order with an extended lead time.
The project does not justify Class 1 durability – oak or larch meet the requirement at a lower cost.

Frequently Asked Questions

Doussie is the French commercial name for Afzelia bipindensis, one of the Afzelia species. At SM WOOD we use the generic term Afzelia, which covers A. africana, A. bipindensis and A. quanzensis – species with similar properties, African origin and the same Durability Class 1.

It depends on the criteria. In terms of hardness: Afzelia wins – 8230 vs 7620 N Janka. In terms of natural durability: Afzelia wins – pure Class 1 compared to Class 1-2 for merbau. Regarding tannin issues: Afzelia wins – it does not have the red staining issue specific to merbau. Thermally: it's a tie – λ ~0.19 for both. In practice: Afzelia is a step above merbau in durability and hardness, though more difficult to process due to the interlocked grain.

Recommended and ethically necessary. Afzelia africana is listed as IUCN Vulnerable and Afzelia bipindensis as IUCN Near Threatened. FSC provision is discussed at the quoting stage. For Afzelia orders we discuss FSC provision at the quoting stage.

λ ~0.19 W/m·K – among the highest in the compared range. The Uf-value of an Afzelia frame is higher than spruce or meranti. Exact Uf, Uw, Ug, g-value, psi-spacer and dB values for PHPP are provided on request for the specific configuration.

Yes – Wood Database specifies resistance to acids and bases. For buildings with specific chemical exposure (laboratories, workshops with corrosive vapours, humid environments with chemicals), Afzelia offers this documented property.

Contact and Quote

SC SM WOOD PRODCOM SRL – manufacturer of laminated wooden windows and doors, including bespoke Afzelia joinery. Florești, Ferma 9, Hala 8A, 407280, Cluj.

www.smwoodprodcom.ro

+40 740 647 877

+40 745 512 371

sm.wood.prodcom@gmail.com

Bespoke Afzelia windows and doors – made to order
Laminated wood IV92/D92 windows – complementary series
FSC-certified tropical wood on request

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Afzelia Windows - Hardest Wood, Janka 8230 N