Thermo Ash

Novawood Thermo Ash


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.


Technical Information

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.


Additional services

Laminated sections available for bespoke large dimension requirements.

Surface treatments including oiling and charring are available to order.