Ambara® Thermally Modified Wood Siding

Ambara® is thermally modified Ayous — Triplochiton scleroxylon, also sold as Obeche, Abachi or Wawa — a lightweight West African hardwood transformed by heat and steam into a premium exterior cladding. It is the answer to the clear Western Red Cedar shortage: knot-free, more dimensionally stable than vertical-grain cedar, and considerably less expensive than A&Btr VG.

Raw Ayous is a cream-colored, Class 5 durability wood that has no business outdoors. Run to a Thermo-D schedule it comes out an even caramel brown right through the board and jumps to Class 1 durability — comparable to clear all-heart Western Red Cedar, with none of cedar’s knots, price or supply anxiety.

One thing to be plain about: Ambara is a siding and paneling wood. At 285 lbf on the Janka scale it is soft and light — perfect on a wall or a ceiling, wrong underfoot. It is not a decking board, a stair tread or a structural member. If you want thermally modified decking, that is Korina.

Ambara exists because clear cedar got scarce and expensive. On the specifications that matter for cladding it holds up well against the wood it replaces.

Ambara is real wood changed with heat and steam alone — no chemicals, no preservatives, nothing added. The wood is heated to 180–230°C (356–446°F) in a controlled, oxygen-free chamber over 24 to 72 hours.

At those temperatures the hemicellulose breaks down and the cell structure permanently reorganizes. The sugars and starches that feed insects and decay fungi are converted, and the wood turns hydrophobic — it absorbs up to 50% less moisture than untreated stock. That single change is what kills the swelling, shrinking, warping and cupping that ruins ordinary siding, and it is why raw Ayous goes from strictly-indoors to a Class 1 exterior material.

The caramel color is a byproduct of the same process rather than a stain, which is why it runs through the board. Steam is reintroduced during cooling to bring moisture content back to a stable 6–8%, ready to mill.

We stock Ambara as 1x6 tongue-and-groove with a flush back, in two reveals:

• 1x6 T&G Edge-Vee — the classic V-joint line, 5″ of coverage per board.
• 1x6 T&G Nickel Gap — the tighter, more contemporary shadow line, also 5″ coverage.

Both are FAS grade, thermally modified and kiln-dried, priced by the lineal foot. Ambara is also produced in bevel siding, rough-sawn boards from 1x4 through 5/4x12, and S4S in 2x stock — if your drawing calls for a profile we do not have on the floor, ask us and we will source or mill it through our custom millwork shop.

• Ordinary tooling. Mild steel is fine; Ambara is easy to cut and easy to install, and it does not blunt blades the way a tropical hardwood does.
• Nail, screw or clip. It takes fasteners readily, and clip systems give a fully concealed face — see the ExoDek and ExoClad clip systems.
• Detail it as a rainscreen where you can. Ambara is stable, but a vented cavity behind the cladding is what makes any wood wall last.
• Finish the cut ends if you are staining, so the caramel does not read differently at the joints.
• Not underfoot. 285 lbf will mark under furniture and heels. Walls and ceilings only.