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Ash Thermowood decking

Product code: ter-jas-the-20x132

Thermowood ash decking,
size: 20x132x1200-4200 mm,
profile: both side smooth

Availability: In stock
119.57 €  / m² Price without VAT:
144.67 €  / m²
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Detailed Description

Ash ThermoWood decking Masterdeck

Specie: ash in original thermal teat modification ThermoWood
Botanical name: Fraxinus
Size: 20x132x1500-3600 mm
Density: approx 590 kg/1m3
Durability class EN350: 1
Modification: original ThermoWood, heat modification D, for exterior
Usage: exterior decking
Packing: loose on pallets
Profile: S4S, E4E ( both side smooth)

Specification points

ThermoWood - original heat treatment of wood with improved properties

It has been known for centuries that tanning a wood surface in an open fire increases its durability when used outdoors. Heat treatment of wood as such is a very old technology, known and used in ancient times by Native American tribes, who noticed that fire-tanned wood has a much longer life, resistance to rot and weather. The wood treated in this way was used, for example, for the construction of Tepee Indian dwellings. Archaeological finds have confirmed that the Vikings used this method of wood treatment for their buildings and fortifications. Heat treatment of wood was scientifically studied in the 1930s in Germany and then in the 1940s in the United States. This research was followed up in Germany in the 1950s and in Finland, France and the Netherlands in the 1990s. The most intensive and comprehensive research work was carried out by VTT in Finland. Significant practical research is also carried out by YTI - Institute of Environmental Technology. The current ThermoWood modification is produced by a method developed by VTT. Wood material exposed to high temperatures is protected by steam. In addition to protecting steam, it also affects the chemical changes that take place in the wood. The result of the treatment is the creation of an environmentally friendly ThermoWood product. Due to this treatment, the wood darkens, is more stable than normal wood in conditions of changing humidity and its thermal insulation properties improve. If carried out at a sufficiently high temperature, the treatment also makes the wood resistant to rot. Our company only imports certified ThermoWood wood.

Beware of imitations! What is the difference between ThermoWood and Thermo ash, for example?

Only wood produced by the original Finnish method developed by VTT and approved by ITWA can use the ThermoWood label. It is a registered trademark of the international association ThermoWood. However, in the market we can find non-original products, often of unknown origin, which are not produced by the original method and must not be called ThermoWood. They are therefore most often referred to as Thermo-pine, thermo-wood or other similar nomenclature. If these products are produced at a lower temperature, for example 180 ° C, they are not intended for outdoor use and have a lower resistance than wood modified at a temperature of 212 ° C. The thermal modification of 212 ° C and more is intended for outdoor use.

ThermoWood with Thermo-D modification, temperature 212°C with increased resistance to the exterior

The original ThermoWood has two standard treatment classes, Thermo-S and Thermo-D depending on the treatment temperature. As soon as the processing temperature exceeds 200 ° C, the properties of the wood change rapidly. The letter "S" in "Thermo-S" means "stability". The production takes place at a temperature of 185 ° C and together with the appearance, stability is a key feature for the end use. The Thermo-S class is generally intended for indoor use. According to the EN 113 classification, the thermal modification meets the requirements of class 3. The letter "D" in "Thermo-D" means "durability". Along with appearance, biological durability is a key property. Thermo-D class according to EN 113 meets the requirements of class 2. ThermoWood type D is processed at a temperature of 212 ° C, it is designed due to its increased durability for outdoor use and exposure to weather conditions. We import the ThermoWood we supply only in thermal modification D.


Heat treatment gives wood new useful properties, such as long durability, excellent resistance to rot, decay and weather.

Color and weathering

The surface of Thermowood turns gray easily and weathering causes the weathering of the wood surface. Thermowood easily accepts the same types of surface coatings as other woods. Thermowood easily accepts and absorbs oil-based coatings. When using water-based coatings, the absorption into the wood is slower, so it is recommended to use substances with a longer drying time in order to achieve sufficient saturation of the wood. If you want to restore the original color of the wood, use a professional Saicos dehumidifier (new window) according to the technical sheet. Then treat with a suitable protective coating.


Observe two important factors when processing ThermoWood:
Use sharp tools for the best results. Thermowood is slightly more fragile and drier than conventional wood, so cutting should be done at a slower speed than cutting normal wood. Lack of resin makes cutting and grinding easier. The dust that comes from sawdust during processing is really dry and fine, so it is recommended to use respirators. Work areas should be equipped with their own ventilation system to remove dust. Thermowood's heat treatment process can increase the susceptibility of wood to cracking. There may be slight differences in the width of the wood, due to the different expansion of the wood during moisture compensation, between the radial and tangential growth of the wood. In wood that is exposed to external climatic influences, cracks, deflection of the so-called troughs, torsion and rotation, cracks and fissures, especially at the ends of the boards due to drying, changing depending on relative humidity or changes in climatic conditions, small holes after wood damage insects. The above-mentioned characteristics of wood cannot be considered a defect.
Always pre-drill the screw holes to prevent the material from cracking. The use of self-tapping screws without pre-drilling is not recommended. It is recommended to use low threaded screws. It is very important to use countersunk stainless steel screws and fasteners, for outdoor or outdoor use.

Knots and other natural features of wood

Knots and eyelets, healthy or partially fused, cracks around the knots, marrow run-in, resin channels, marbling and other natural features are an integral part of the wood.


When storing wood before and during installation, make sure that the wood is not exposed to direct sunlight, rain, snow or other external influences. It was well covered or best stored in roofed unheated areas, with relative humidity values ​​equal to outdoor humidity. At the same time, sufficient interleaving of the wood was ensured, enabling air ventilation and the prevention of the formation of mold. Failure to follow these instructions may result in twisting, deformation or other changes to the wood during storage.


Regularly clean the terrace from dirt, soil, sediment and pollen. This will prevent macroporous dirt from penetrating the wood. Under objects such as parasol stands, flower pots, bowls, mats, under which water and moisture settle, there is no possibility of fast and natural drying of the wood. Long-term moisture and dirt stains can form under these objects. Therefore, carry these objects standing on the terrace from time to time or ensure that there is natural drying and ventilation of the air under them. This will prevent the formation of dark spots on the wood. More information about the care of wooden terraces.


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We will be happy to advise you on the choice suitable accessories.

We will show you our products before purchase in our warehouse. Wood is a natural material, each piece is a unique original. The supplied wood will be different from the displayed photos and samples.

Call us on +420 220 879 443

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  • Cash on delivery (you pay when picking up the goods to the courier in the Czech area only )
  • By bank transfer (we will send the goods immediately after the amount has been credited to our account)