Thermowood Cladding Treatment and Maintenance

Lunawood Thermowood cladding is a sustainable wood material that retains its shape throughout all seasons. With proper Thermowood treatment, the cladding retains its beautiful brown appearance and remains in good condition for many years. Although thermowood retains its technical benefits without a separate surface treatment, the surface treatment can achieve the longest possible service life for the Thermowood facade. It also reduces small cracks that are typical to wood materials. When left untreated, Thermowood turns silver-gray under the influence of UV radiation over time.

In this guide, we explain how Lunawood thermowood cladding should be maintained and surface treated.

Thermowood surface treatment retains the brown color and reduces cracks

If you wish to preserve the beautiful brown tone of Lunawood Thermowood, this can be done with the help of surface treatment agents designed for wood. Treating the cladding boards with tinted or pigmented wood oil, wax, wood-protecting stain, varnish or paint – which contains a UV-filter – can retain the brown color.

Thermowood surface treatment can be applied either before or immediately after installation using only a thin coat. Any excess should be wiped off. The surface treatment should be renewed as necessary. The need for re-treating varies depending on the climate, amount of usage and the degree of exposure to UV-light. With opaque painted untreated wood the typical interval between maintenance is approximately 5 years. With Lunawood Thermowood the maintenance interval in painting can be greatly extended, possibly three times longer than usual. By using a more stable material considerable costs can be saved in cladding taking into consideration the entire lifespan of the product.

Lunwood turns eventually gray in sunlight without a surface treatment. The speed of change is always individual depending on the project and climate conditions. Project: Skibby Børnehus Kindergarden

Natural Graying of Thermowood

Like all wood products, Lunawood turns gray when exposed to UV radiation, and over time, small cracks may appear on the surface. The silver effect begins to show in a relatively short time, 3-6 months after installation, depending on climatic conditions. Lunawood is naturally weather and rot resistant and does not require maintenance if a gray surface is desired for the cladding.

Read more about the graying here:
The natural greying of Lunawood Thermowood

Best surface coatings for Thermowood

Most good quality surface coatings for un-modified wood are suitable also for thermowood. Lunawood can be treated with tinted or pigmented wood oil, wax, wood-protecting stain, varnish or paintwhich contains a UV-filter – to help retain the original surface color. Thermowood surface treatment can be applied either before or immediately after installation. To refresh the surface completely it is possible to wash the surface of discolored timber, allow to dry thoroughly and re-coat. Care should be taken to apply only sufficient water pressure to remove the discoloured surface and not to raise the grain of the timber.

Black Spots on a wood surface

Impurities in the air such as soot or pollen, or metallic dust can cause small black spots on the surface of the cladding. Black spots can be prevented by using pigmented oil right after installing the cladding. Black spots often disappear by themselves over time from untreated Lunawood as the boards turn grey.

Black spots can be removed by following these instructions:

1.  Carefully wash the surface using a detergent intended for decking and cladding (such as Tikkurila Tehopesu).

2.  Rinse and allow the cladding dry thoroughly.

3.  If the surface has a clear film after washing, remove it before continuing.

4. Smooth the surface using a fine sandpaper if needed.

All Lunawood Thermowood claddings and battens can be treated in the same way. Picture: Luna Triple 32x140 panel.

Always install the thermowood cladding according to the official instructions

The installation should be done according the manufacturer’s guidelines to ensure the highest possible quality and beautiful outcome.

For detailed information please see the  Lunawood installation guides:


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