For Architects & Designers

Specify woodbuilt to last.

Thermally modified Canadian hardwood for cladding, decking and interiors. Made in Bathurst, New Brunswick.

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60 yr

Siding warrantyAgainst rot and decay

25 yr

Decking warrantyAgainst rot and decay

Thermo-D

ITWA certifiedAudited every year

Chemicals addedHeat, steam and water only

Why Ironbark

A natural material
that behaves.

Ironbark is ash, thermally modified to the International ThermoWood Association’s Thermo-D class for exterior use. Heat and steam permanently change the wood’s structure, removing what fungi feed on and what draws moisture in. The change runs all the way through the board, and nothing is added.

We specialize in hardwoods: ash, maple, birch and oak. Our kilns, process and finished boards are audited every year by an outside inspector, and our President and CEO, Bob Lennon, sits on the ITWA Board.

Exterior work needs Thermo-D. Specify the class by name.

Dimensional stability

Shipped at 4–6% moisture, with an equilibrium moisture content well below 20%. Swelling and shrinkage are up to 40–50% less than untreated wood.

Decay resistance

Rated for Use Class 3.2: exterior, above ground and fully exposed to the weather.

Colour through the board

A rich brown from face to core. Clear CUTEK protects the wood and lets it grey naturally; pigmented CUTEK holds the colour.

Responsibly sourced

From well-managed forests, bought from sawmills across Canada. Modified in Bathurst, New Brunswick.

Hidden fastening

Our Snap-To-It siding and decking are milled for GRAD® hidden clips, which ThermalWood Canada holds the exclusive rights to produce outside of France. A clean face, with no visible screws.

Specifier essentials

Ironbark at a glance.

The key details for your drawings and specifications. Dimensioned profile sheets are linked below.

Material: Thermally modified ash, Thermo-D class (ITWA)
Grade: FAS Select & Better
Siding: Snap-To-It siding in single, double and triple rabbet, for exterior or interior. 5⅛–5¼” (131–133 mm) wide; 13⁄16″ (21 mm) thick
Decking: Snap-To-It back-groove decking, 4⅝” (118 mm) wide: 4/4 at ⅞” (22 mm) and 5/4 at 1″ (25 mm) thick. Side-groove decking 4¾–5½” (120–140 mm) wide. Lengths 6–12 ft (1.8–3.7 m), cut on 16″ (406 mm) intervals
Fastening: GRAD® hidden clips. Where face-fixing is required, stainless steel: 304 (A2) minimum, 316 (A4) near salt water
Finish: CUTEK Extreme recommended on all exterior applications, clear or pigmented. Factory pre-coating available
Custom: Custom profiles milled to your drawings; custom lengths for a 10% surcharge
Lead time: About 4–6 weeks from purchase order

Ironbark siding fastened with hidden clips

Not a structural material. Thermal modification lowers bending strength by about 10%, and the wood is not strength-graded. Specify it on a rated structural frame, above ground and out of standing water.

Technical resources