Thermal modification enhances the natural characteristics of American ash to create a product which is extremely durable and stable with an attractive appearance.
The kiln dried timber is heated to 212°C at which point the timber’s natural properties change and it turns a rich walnut brown colour.
The process uses only heat and water and is completely chemical free with the energy for the kilns generated from wood waste.
All the timber used to produce Thermo Ash is FSC certified, achieving the highest environmental standard.
Durability – Class 1 – Suitable for Exterior use, in ground contact without protection (in accordance with En prCENT/TS 15679)
Stability – As a result of the Thermowood process the stability is vastly improved in comparison to un-modified wood.
Thermo Ash is available in two grades: FAS and Extra.
FAS – graded in accordance with the NHLA grading rules
Extra grade is 3 sides clear and is only available in a skipped / dressed finish. Extra grade is selected after the modification process to provide the highest quality product.
Rough lumber size / invoicing size Skipped / Dressed Size Maximum achievable finish size
26mm x 102mm 23.5mm x 95mm 21mm x 90mm
26mm x 127mm 23.5mm x 120mm 21mm x 115mm
26mm x 152mm 23.5mm x 136mm 21mm x 132mm
26mm x 178mm 23.5mm x 165mm 21mm x 160mm
26mm x 204mm 23.5mm x 180mm 21mm x 170mm
26mm x 228mm 23.5mm x 195mm 21mm x 185mm
26mm x 254mm 23.5mm x 220mm 21mm x 210mm
32mm x 102mm 29mm x 95mm 25mm x 90mm
32mm x 127mm 29mm x 120mm 25mm x 115mm
32mm x 152mm 29mm x 136mm 25mm x 130mm
32mm x 178mm 29mm x 155mm 25mm x 150mm
38mm x 152mm 34mm x 136mm 30mm x 132mm
38mm x 178mm 34mm x 158mm 30mm x 150mm
52mm x 152mm 45mm x 136mm 42mm x 132mm
52mm x 228mm 45mm x 195mm 42mm x 185mm
Lengths 1800mm / 2100mm / 2400mm / 2700mm / 3000mm / 3300mm / 3600mm
Machined profiles are available to order on a forward basis.
Laminated sections available for bespoke large dimension requirements.
Surface treatments including oiling and charring are available to order.