Cumaru: the complete guide to cumaru exotic wood

Cumaru is an exotic wood, like ayous, coming from Latin America, with characteristics that are of great interest for your construction projects, outdoors as well as indoors. Durable, dense and stable, cumaru wood is a major ally when it comes to withstanding the vagaries of the weather and heavy loads.

Would you like to know more about cumaru wood? WoodPartners explains everything:

• What is cumaru wood?
• What are the characteristics of cumaru?
• Cumaru wood: what is it used for
• How do you maintain exotic cumaru wood?
• Other questions about cumaru

What is cumaru wood?

Cumaru exotic woodcomes from Latin America and belongs to the Fabaceae family. It has various botanical names: Dipteryx Alata, Dipterix micrantha, Dipterix odorata, Coumarouna odorata and Dipteryx polyphylla.

Cumaru shows colour variations ranging from red to yellow, giving it the attractive, authentic appearance that many people look for. Thanks to its density and its stability, cumaru wood is also called "ironwood" and has stability and durability that are of great interest for building wooden decks.

Although the leading supplier of cumaru wood is Brazil, different names are used for cumaru depending on the country:

• Bolivia: Almendrillo;
• Brazil : Champanha, Cumaru, Cumaru ferro, Cumarurana;
• Colombia : Sarrapia;
• Costa Rica : Almendro;
• Guyana : Kumaru, Tonka bean;
• French Guiana :Tonka;
• Peru : Charapilla;
• Suriname : Koemaroe.

What are the characteristics of cumaru?

Cumaru has its own advantageous characteristics, such as a strong, pronounced colouring, good stability, resistance to water and moisture and a natural durability that means it does not need to be pressure treated, and which will therefore make it easier for the wood to be recovered afterwards.

Description of cumaru

• Colour : reddish brown to yellow;
• Sapwood (the soft, light-coloured part of the wood that forms each year under the bark): clearly distinct;
• Grain : medium;
• Grain direction or fibre orientation : interlocked;
• Interlocked grain or direction contrary to the axis : yes.

Description of the exotic cumaru wood log

• Diameter : between 50 and 90 cm;
• Thickness of the sapwood : between 2 and 3 cm;
• Preservation in the forest : good.

The physical properties of cumaru wood

• Density (at 12% moisture content with 1 MPa = 1 N/mm²): 1.07;
• Hardness (at 12% moisture content with 1 MPa = 1 N/mm²): 13.1;
• Volumetric shrinkage coefficient : 0.73%;
• Total tangential shrinkage (TS): 7.7%;
• Total radial shrinkage (RS): 5.5%;
• Ratio between TS and RS : 1.4;
• Fibre saturation point : 22%;

The natural durability and treatability of cumaru

• Resistance to fungi: class 1, very durable;
• Resistance to dry wood insects : class D, durable;
• Resistance to termites : class D, durable;
• Treatability : class 4, not treatable;
• Use class: wood class 4, for use in contact with the ground or with fresh water.

Drying exotic cumaru wood

• Drying speed: slow;
• Risk of distortion : low;
• Risk of case-hardening (accidental hardening): present;
• Risk of checks (splits): high;
• Risk of collapse (waviness, separation of the wood): no known risk.

Sawing and machining cumaru wood

• Blunting effect: fairly considerable;
• Sawing teeth : stellite-tipped teeth;
• Machining tools : tungsten carbide;
• Suitability for peeling : not recommended;
• Suitability for slicing : good.

Cumaru wood is a hard species with interlocked grain, which makes it difficult to saw and to machine.

Assembling cumaru

The assembly of cumaru is carried out in two steps:

• Nailing and screwing: good holding, pre-drilling required;
• Gluing : can prove difficult for this dense wood; the instructions given on the glue used must be followed.

Cumaru wood: what is it used for?

In France, cumaru wood is mainly used for making decks because of its durability and its stability. It is, however, also known for other uses in boat building, hydraulic works and the building of roof structures.

• Heavy timber framing: the high density and the good stability of exotic cumaru wood make it an ideal species for building heavy timber frames.

• Boat building: because of its natural durability and its resistance to moisture and fresh water, cumaru can easily be used in boat building.

• Hydraulic works: rated class 4 and endowed with good strength, cumaru wood is the perfect ally for various hydraulic works.

• Flooring: its pronounced, authentic colouring makes cumaru wood a must for laying flooring in your interiors.

• Sliced veneer: the characteristics of cumaru lend themselves to sliced veneer because of its fine shade, its stability and its durability.It is an asset for your various decorating ideas.

How do you maintain exotic cumaru wood?

Because of its strength and its natural durability, exotic cumaru wood needs no particular treatment. However, like many woods, the ageing of cumaru will lead it to turn grey.

If you want to keep its natural shade, you can use a special saturator before it ages. In the event that the cumaru wood has already taken on a greyish shade, you can use a wood brightener so that it recovers its original colour.

What is more, for proper maintenance, we advise you to brush and wash your cumaru decking boards at least once a year. It will last all the longer and its natural appearance will be maintained.

Other questions about cumaru