Silva ThermoWood® is a beautiful, sustainable solid wood material produced using a chemical-free natural process involving heat and steam.
Silva ThermoWood is durable, dimensionally stable and resin free. It is an ideal material for use in exposed areas such as external wall claddings. It can also be used indoors to create a sense of warmth and luxury. As it does not drastically react to changes in temperature and humidity, Silva ThermoWood can be used in any climate. It is a non-toxic natural product which is easy to machine and install.
The heat treatment process alters the colour of the wood to an attractive warm brown colour consistent throughout the section of the piece. The colour of ThermoWood is affected by the treatment temperature and time, so with quality control, it is possible to ensure that the hue stays inside certain colour values, thus achieving consistency from one batch to the next. When ThermoWood is exposed to UV-light it will turn silver grey, unless protected by a pigmented surface protection.
Silva ThermoWood has a decay resistance of durability class 2 (durable) according to the EN 113 standard. The heat treatment process improves durability, making it an excellent material for use in applications such as exterior cladding where a service life of 30+ years can be achieved, or 60+ years if a surface coating is applied at the outset and maintained periodically.
The lower equilibrium moisture content and the changes in the chemical composition of the wood during the heat treatment process make Silva ThermoWood less able to absorb and release water. This restricts the moisture movement, which significantly decreases shrinkage, swelling and distortion compared with the original untreated material.
The density of Silva ThermoWood is 350 – 480kg/m³ when its moisture content is 6% (typical for RH = 65%, t=20° conditions). The heat treatment process reduces the density by about 10 % on average. Natural variation will occur between individual boards.
The thermal conductivity of Silva ThermoWood is reduced by 20–25% compared with untreated kiln-dried European Pine. As a result of this improvement, Silva ThermoWood has advantages when used in applications such as external and internal cladding and panelling. According to VTT tests ThermoWood’s thermal conductivity λ10 is in the region of 0.099 W/(m K). The corresponding value for untreated kiln-dried European Pine is 0.12 W/(m K).
ThermoWood is available in the following profiles:
Silva also offers ThermoWood corner solutions in a range of profiles. You can view our range of corner profiles here.
To ensure Silva ThermoWood products meet the highest quality standards only specially selected sound (live) knotted wood is used in the production process. The quality of sawn timber is controlled with a general quality grading system. The quality grades are divided into three groups according to the number, quality, location and size of the knots and other features. These are A, B and C grades. The quality grade used to produce Silva ThermoWood is A/B.
Silva ThermoWood is produced from Finnish grown European Redwood (Scandinavian Pine). It is sourced from well-managed and sustainable forests which are fully certified under the Pan European Forestry Certification (PEFC) scheme. The material is bio-degradable and can be disposed of at the end of its service life by either burning or placing into the normal waste system.
According to the Finnish ThermoWood Association, the application of a coating is necessary to protect the wood from the damaging effects of moisture and UV, to help prevent the wood from turning grey and to curb the growth of fungi that produce mould or blue stains. Thermally modified wood can be finished in the same manner as normal wood.
Because ThermoWood has a lower water absorption rate than normal wood Silva uses a specially adapted formula of Sansin Enviro Stain – called SDF HT - which has been developed specifically for use on heat-treated wood.
Silva ThermoWood cladding can be factory coated, enabling it to be installed at any time of year, regardless of the weather or temperature.
Timber delivery charges vary based on the products you have ordered, the location of your delivery, the value of your order and the delivery service you require.
Silva Select delivery – Our cheapest timber delivery service with goods expertly delivered by a member of our team on our own vehicles. Priced at £45 + VAT, orders are typically fulfilled within 7 working days*. Available to selected postcodes only.
Haulier delivery – Our haulier delivery service is for areas where our Silva Select service is not available. Lead-times for this service are guaranteed between 5-7 working days, subject to stock availability. Prices start from £95 + VAT.
Saturday deliveries – please call for a quote.
Free delivery is offered on orders over £2,000 + VAT**
Please note: As with most building materials, delivery is to the kerbside only.
* Typical lead-time for our Silva Select delivery service is 5-7 days although this is not guaranteed. Please allow up to 14 days for delivery especially at peak times.
** Exclusions apply. See Delivery Information tab for further details.