Thermally Modified Wood Siding

Adapting the Process for Hardwoods

The thermally modified wood siding process began with softwood lumber. When Bob Lennon and Jean-François Friolet wanted to use hardwoods like maple, ash, birch, and oak from Quebec, Ontario, New York, Indiana, and Pennsylvania, they had to adapt the equipment. They developed and tested more than 200 treatment recipes to ensure each hardwood species performed at its best.

Workers carefully stack the lumber with two-inch gaps between layers so heat and steam can circulate clockwise. They load the wood into a propane-heated kiln, adjusting temperature and duration for each species to achieve the ideal transformation.

The Science of Transformation

The process physically alters the wood at a molecular level. By changing the sugars, the wood becomes hydrophobic and naturally resists insects and decay. This prevents moisture absorption and gives thermally modified wood sidingremarkable protection against water damage, warping, swelling, and rot. The heat treatment also creates a deep, even coloration that intensifies the longer the wood stays in the kiln.

Expanding the Market for Hardwoods

“Treating hardwood to create a stable, insect- and mold-resistant product has allowed these species to play in markets they couldn’t have entered before,” says Lennon. “They would normally be designated for furniture or interior use, but because of our process, we can take them outside.”

This innovation opened new opportunities. ThermalWood Canada now produces thermally modified wood siding, decking, and outdoor furniture components, along with interior products like flooring, wall and door paneling, furniture, and butcher block countertops.

A Global Reach

ThermalWood Canada ships finished hardwood products, including thermally modified wood siding, across Canada through distributors in Alberta and British Columbia. The company also exports to the United States, several European countries, and the Caribbean.

European builders, already familiar with thermally treated softwood, welcome the expanded range of durable hardwood options. In the Caribbean, termite resistance makes the product especially valuable. In fact, architects in Barbados tested it by placing a piece inside a termite mound for six months. The termites ignored it completely—proof of its superior durability.months,” Lennon says.

Profiles

Our thermally modified hardwood siding can use the same technology as our Snap-To-It decking. Machined grooves on the backside of the siding allow these boards to be fastened to the wall using our GRAD clips. Simply screw the clip onto your strapping and snap the siding in place.

Save up to 30% on your installation time! If that does not work for you, we have other fastening options. Siding comes with a 60-year warranty against rot, In addition you still get that superior structural stability in high humidity and an increase in insulation properties.