Naturally Weathered vs. Instant Grey Cladding: Achieving low-maintenance grey wood cladding with Lunawood ThermoWood®

Grey wood cladding is increasingly becoming the go-to choice for facade design in urban environments. It’s not surprising, given that the grey hue of the wood offers an appealing and timeless look for grey cladding on a house, and it also can reduce the maintenance typically required for the exterior of a building. In this article, we present two distinct approaches to achieving a stunning grey wood cladding in a sustainable manner using Lunawood ThermoWood®.

Initially, all Lunawood products have a uniform, rich golden-brown color due to the thermal modification process. However, when left untreated and exposed to enough sunlight and rain, this color will naturally transition to grey, which is often the preferred aesthetic for exterior cladding. This grey tone is sought after for its elegant and sophisticated appearance on cladding.

In some instances, the process of natural weathering and the time it takes for the wood to achieve this desirable silver-grey can be a concern, especially for projects that are situated in areas with less sunlight. For such scenarios, Lunawood’s pre-surface treated Luna Arctic Layer is the perfect solution, offering an immediate grey finish that is perfect for grey wood cladding, without the wait.

The Luna Arctic Layer features a brushed surface and silver grey color

Mastering Grey Cladding with Luna Arctic Layer

When a project demands the sophisticated look of grey wood cladding without the wait, pre-surface treated grey cladding becomes the ideal choice.

Lunawood’s shiplap Luna Arctic Layer is a thermally modified grey cladding suitable for buildings in any climate. Crafted from Nordic Spruce, the Luna Arctic Layer cladding features a brushed surface that is enhanced with a stunning silver-grey coating. The magic of this coating lies in its ability to gradually fade on weather-exposed parts while persisting on shadier and more protected areas. The outcome is a natural, uniform appearance that, best of all, requires only little maintenance.

The Luna Arctic Layer showcases the beauty and authenticity of natural wood with its brushed surface that elegantly highlights the wood grain. This grey wood cladding’s modern, straight edges create subtle shadows between panels, adding depth and character to the facade. Available in two widths, 142 mm and 188 mm, Luna Arctic Layer enhances outdoor aesthetics and is also perfectly suited for indoor applications. This allows for the use of the exact same grey product from the outside to the inside, ensuring a uniform flow.

Learn more about Luna Layer cladding at the Luna Layer product page.

Naturally Weathered Grey Cladding

As a result of the thermal modification process, Lunawood products exhibit a uniform “baked” golden brown color when new. This brown color gradually turns grey when left untreated outdoors, influenced by UV radiation and rain. It is good to remember that even after turning grey, Lunawood ThermoWood® maintains its excellent technical properties. For exterior applications, this naturally weathered grey cladding does not necessarily require additional surface treatment, which simplifies maintenance and is cost-effective.

To comprehend why thermally modified wood, like other wood materials, turns grey over time, it’s essential to delve into the environmental factors contributing to wood’s deterioration and aging. These factors include both biotic and abiotic elements that induce changes in wood.  It’s an important consideration for those selecting grey wood cladding as each of these factors can affect different species and environmental conditions differently.


Factors causing the greying of wood include:

  • Sunlight: UV radiation has the most significant effect on wood color, breaking down the lignin and causing greying.
  • Moisture: Air moisture accelerates greying. The most pronounced greying occurs in environments where the wood is cyclically exposed to UV radiation and rain.
  • Soil Properties: The chemical composition of soil, such as calcium content, can change the acidity of the cell fluid and thus affect wood color.
  • Fungi: Chromocenic fungi can alter the wood color.
  • Air Impurities: Metal ions and other impurities in the air can lead to wood discoloration.

It’s important to note that these factors can affect different tree species and environmental conditions in various ways.

As mentioned, both untreated and thermally modified wood turn grey due to natural phenomena such as the sun’s UV rays and rainfall, which discolour the surface layer of the wood, creating a unique shade not achievable through painting. However, greying is a gradual process, and not all wood species grey uniformly. Additionally, the same wood species may grey differently on different parts of the same building and under different climatic conditions. For instance in European countries, solar radiation can cause a south-facing façade to degrade more than twice as quickly as other sides of the building.

Learn more about the natural greying process from our article
The Natural Greying of Lunawood Thermowood”


The Casa A's diagonal exterior cladding is made of Lunawood battens and allowed to grey naturally. Architect: REM'A arquitectos

The Benefits of Opting for Grey Wood Cladding

Choosing grey wood cladding, such as Lunawood’s solutions, offers a versatile and aesthetically pleasing option for building exteriors. The decision to use grey cladding on a house is influenced by several factors, including aesthetic preferences, cultural influences, material compatibility, and environmental conditions.

Reasons for opting for grey wood cladding are numerous:

  • Aesthetic reasons: The grey tone can complement the architectural design, enhancing the facade’s features.
  • Durability: Naturally weathered Lunawood Thermowood Cladding as well as pre-treated Luna Arctic Layer cladding are durable in all climates and easy to maintain. As a result of the thermal modification process, these solutions are also dimensionally stable and don’t necessarily require surface treatments.
  • Sustainability: Lunawood Thermowood cladding is free from toxins and is produced in Finland from PEFC-certified Finnish forests, ensuring a small carbon footprint (Lunawood EPD). The surface treatment of Luna Arctic Layer is not harmful at all, so it is also suitable for indoor use.
  • Other material choices: Grey is a neutral color that pairs well with other materials, such as concrete, glass and steel, allowing for a harmonious design scheme.
  • Environmental suitability: Grey can blend well into the urban surroundings as well as natural environments.

The use of colour in architecture can vary greatly between buildings, designers, and cultures. Overall, both the colours and the materials chosen have a significant impact on the appearance and atmosphere of a building and can also influence people’s experiences and reactions to the space.


In the B Home project, the cladding under the roof eve is still brown after 5 years of installation. Architect: [baragaño] arquitectos

Tailored support to achieve the desired grey cladding

In summary, whether you are drawn to the elegance of naturally weathered grey cladding or the instant charm of the pre-treated Luna Arctic Layer, Lunawood Thermowood offers sustainable, durable, and aesthetically pleasing options for any project. Understanding the nuances of the greying processes and the benefits of each approach allows architects and builders to make informed decisions tailored to their specific needs.

Our professional design support is at your disposal to navigate these choices, ensuring you find the perfect solution for your project. Discover the timeless appeal of grey cladding with Lunawood and reach out to us for further support.



lescouleurs.ch, archdaily.com

Read also

All projects
Sign up for our newsletter
Privacy Policy