What is azobé wood?

Tropical hardwood · Wood guide

What is azobé wood?

Azobé (Lophira alata) is a West African tropical hardwood so dense it sinks in water — and it has been the backbone of Dutch and Belgian waterworks for over a century. It is the wood engineers reach for when nothing else will do.

  • Lophira alata
  • 940–1,100 kg/m³
  • Durability class 1 — even in water
  • West Africa
In brief

The heaviest timber in the register

Azobé weighs up to 1,100 kg/m³ when dry — and up to 1,300 kg/m³ fresh-sawn. That is heavier than water, heavier than most tropical species, and heavy enough that two people can barely lift a single beam.

That mass is exactly why azobé ends up in lock gates, sheet piling and bridge decks. It does not rot, does not creep, and does not deform under the endless cycle of wet and dry that destroys lesser timbers. Durability class 1 under the European standard means it performs even in permanent ground and water contact — a bar that almost no other timber clears.

It grows across West Africa and goes by several names depending on where it is traded: bongossi in Cameroon and Germany, ekki in Nigeria and Britain, aba in Nigeria, and hendui in Liberia and Sierra Leone. The variety of names is itself a clue: this timber is prized and traded everywhere it grows.

Four names, one tree

Bongossi · Ekki · Aba · Hendui — all the same Lophira alata, all the same extraordinary density. The name you encounter depends on where in the supply chain you are standing.

Botanical nameLophira alata
OriginWest Africa
Density (12% MC)940–1,100 kg/m³
Density (fresh-sawn)1,100–1,300 kg/m³
Durability classClass 1 — also in water
ColourDark purple-brown to red-brown
Trade namesBongossi, ekki, aba, hendui
Honest limitation Azobé checks extremely at end grain, deforms strongly during drying, and produces irritating dust when machined. End grain must be sealed; pre-drilling is mandatory; and tight dimensional tolerances are not realistic.

Looking for durable hardwood products for your garden? Browse our selection:

Properties

Why azobé makes it into civil engineering

Four properties explain why this timber dominates water-contact applications — and why nothing cheaper has replaced it.

Extreme density

940 to 1,100 kg/m³ at 12% moisture content. Water barely penetrates, and without moisture penetration there is no decay.

Exceptional wear resistance

An azobé bridge deck withstands heavy vehicle traffic for decades without measurable surface loss. Few timbers come close.

Durability class 1

The highest European rating — valid even in permanent contact with water and soil, where nearly every other timber species fails.

High bending strength

Long spans without deflection. That is why azobé appears in bridge structures, not just cladding or decking.

Salt-water resistance

Port structures and lock gates have relied on azobé in tidal and salt-water environments for generations.

No chemical treatment needed

Unlike softwoods used in water contact, azobé needs no preservative treatment to achieve class 1 durability. The density does the work.

How azobé compares to other hardwoods

Teak is the classic garden hardwood — beautiful, stable, well-mannered. Azobé is an entirely different animal: a structural timber engineered by nature for extreme conditions. The comparison below shows why they serve very different purposes.

For garden furniture and terraces, teak and acacia hardwood remain the first choices — lighter, easier to work, and far more pleasant to sit on.

PropertyAzobéTeak
Density940–1,100 kg/m³630–720 kg/m³
Durability classClass 1Class 1
MachinabilityDifficult — very hardModerate
Stability (drying)High movementStable
Garden furnitureNot suitableExcellent
Civil engineeringExcellentLimited
Applications

Where azobé is used — and where it is not

Azobé is a civil engineering timber. Understanding where it belongs — and where it does not — saves costly mistakes.

ApplicationWhy azobéAlternative
Sheet piling & bank protectionDurability class 1 in permanent ground and water contactBilinga, or steel
Lock gates & fender systemsMass and wear resistanceBilinga
Bridge decksBending strength and surface durabilityIpé, steel-timber composites
Harbour works & jettiesResistance to salt water and marine borersBilinga
Railway sleepersLoad-bearing capacity and service lifeConcrete
Garden furnitureNot suitable — too heavy, too coarseTeak, acacia, impregnated pine
Garden terrace deckingPossible but impracticalIpé, hardwood
Not for the garden Azobé is a civil engineering material. It is too heavy to move, too coarse for furniture work, and checks aggressively at the end grain. For garden furniture, look at teak or acacia; for a terrace, ipé is the better tropical option.

Garden hardwood you can actually work with

If azobé's weight and coarseness make it unsuitable for your project, these hardwood products show what well-chosen garden-grade timber looks like:

Practical guidance

Working with azobé

The same density that makes azobé indestructible in service makes it demanding to process. Anyone specifying or handling this timber needs to know these rules before the first cut.

  • Always pre-drill — nailing without pre-drilling splits the timber. Use hardened screws or bolts.
  • Seal end grain immediately — fresh-cut ends must be coated with a paraffin wax or end-grain sealer on the same day they are cut.
  • Allow slow, sheltered drying — rapid surface drying causes severe checking. Stack with spacers in a sheltered, ventilated area.
  • Wear a dust mask — azobé dust is a respiratory irritant. Use extraction and appropriate PPE when machining.
  • Use carbide tooling — HSS blades blunt within minutes on azobé. Carbide-tipped saw blades and router bits are essential.
  • Plan for movement — this is not a dimensionally stable timber during the drying phase. Allow generous tolerances in joinery.

Azobé vs. fir vs. pine

The contrast with common softwoods is striking — and explains why azobé is a specialist material rather than a general-purpose one.

AzobéFir / Pine
Density940–1,100 kg/m³420–500 kg/m³
Durability (untreated)Class 1Class 4–5
WorkabilityVery difficultEasy
Weight per m³>1 tonne~450 kg
Main useWater engineeringConstruction, garden

For most garden and construction projects, fir or pine — often pressure-impregnated — is the practical choice.

Quick answers

Frequently asked questions about azobé wood

How heavy is azobé exactly?

940 to 1,100 kg/m³ at 12% moisture content, and 1,100 to 1,300 kg/m³ fresh-sawn. For comparison: fir sits around 450 kg/m³ and teak around 650–720 kg/m³. A single azobé beam can weigh more than double the equivalent fir timber.

Can azobé be used in salt water?

Yes — that is one of its defining strengths. It has been used in harbour works, lock gates and tidal fender systems for many decades. Its density limits water infiltration so effectively that marine borers find it extremely difficult to penetrate. Bilinga is a comparable species for the same application.

Why does azobé check (crack) at the ends?

Because of the combination of high density and strong movement during drying: the end grain dries faster than the core, and the resulting tension stress causes surface checks (splits). Sealing end grain with a paraffin wax emulsion or purpose-made coating on the day of cutting is the standard remedy. It does not eliminate checking entirely, but it substantially reduces it.

Is azobé suitable for a terrace or garden decking?

It is technically possible, but it is not the logical choice. Azobé is too heavy to handle easily on site, too coarse in texture for comfortable barefoot use, and genuinely difficult to machine without specialist tooling. For a tropical hardwood terrace, ipé is the standard recommendation. For garden furniture, teak or acacia hardwood are far better suited.

Does azobé need any maintenance or treatment?

In structural water-contact applications, no preservative treatment is needed — class 1 durability is inherent to the wood itself. In above-ground uses (bridge decks, for example), a periodic surface oil can reduce checking and maintain appearance, but it is not required for the timber's survival. This contrasts sharply with pine or fir, which must be pressure-treated to achieve comparable outdoor durability.

What is the difference between azobé and teak?

Both are tropical hardwoods with durability class 1, but they serve entirely different markets. Teak (630–720 kg/m³) is dimensionally stable, smooth-textured, pleasant to work, and has been the benchmark for garden furniture and boat decking for centuries. Azobé (940–1,100 kg/m³) is nearly twice as dense, far harder to machine, and coarse in texture — but delivers unmatched performance in structural water-contact applications. Choose teak for furniture; choose azobé for civil engineering.

Further reading

Azobé in perspective

The heaviest timber in the register — and on the opposite end from balsa. If your project calls for something lighter and more workable, these guides show the alternatives.

Teak wood guide What is hardwood? Douglas fir guide
Fir wood Pine wood

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