The science of stability: timber slat facades that stay in line 

But there’s a catch. Wood is a living material, and in its untreated form, it reacts to the environment. Over time, timber slats may twist, cup, or warp, creating uneven lines and gaps that compromise the facade’s clean aesthetic. What started as a precise architectural vision can become a maintenance challenge. 

At Thermory, we believe beauty should last. That’s why we focus on one property above all: dimensional stability. 

The problem with conventional timber slat facades

All wood absorbs and releases moisture depending on the environment. This constant exchange means that in humid or rainy climates, boards expand — while in dry or hot conditions, they shrink. The result is movement in every direction: 

• Warping and twisting, creating uneven planes. 

• Cupping, where the board curves across its width. 

• Visible gaps, disrupting the rhythm of the facade. 

For architects, these changes undermine the visual integrity of their design. For contractors, they mean callbacks, adjustments, and disappointed clients. And for building owners, they mean higher maintenance costs over the building’s lifetime. 

Excellent dimensional stability: how thermal modification transforms wood 

The solution lies in Thermory’s thermal modification process. Using only heat and steam — no chemicals — we permanently change the wood at a cellular level. 

• Reduced equilibrium moisture content: Wood’s physical and chemical properties change during thermal modification. When it’s heated, the wood releases moisture and its chemical composition is transformed.

• Minimized swelling and shrinkage: Thermal modification lowers the wood’s absorbency, meaning that exposure to moisture no longer causes it to swell as much.

• Improved dimensional stability across climates: From damp northern Europe to hot, arid deserts, the wood remains stable. 

Think of it as training the wood to resist the natural impulses that cause movement. The cell walls are altered so they no longer react to humidity in the same way. The result? Timber slats that stay straight, aligned, and true to the architect’s vision. 

Read more about thermally modified wood.

Why this matters for slatted facades 

When it comes to timber slat facades, dimensional stability isn’t just a technical benefit — it’s the foundation of design excellence. 

• Straight lines that last: Architects can be confident that their carefully planned geometry won’t drift over time. 

• Even gaps, perfect rhythm: Timber slat facades rely on precision spacing; stability guarantees that rhythm endures. 

• Reduced maintenance: No need to constantly adjust, replace, or refinish slats that have moved out of place. 

• Climate resilience: Whether installed on the coast of Northern Europe or in the middle of a hot desert, Thermory slats hold their shape. Read more about thermowood’s durability in different climates.

Project Spotlight: Powerhouse Telemark, Norway

One of the most striking examples of timber slat facades in Europe is Powerhouse Telemark in Porsgrunn, Norway, designed by internationally renowned architects Snøhetta. This 11-story office building is celebrated as one of the world’s most energy-positive commercial structures, producing more energy over its lifespan than it consumes. 

At the heart of its bold design is a facade clad in Thermory Benchmark thermo-pine slats. The dimensional stability of the thermally modified wood was a crucial factor in ensuring the precision of the building’s sharp lines and uniform rhythm. In Norway’s challenging climate — with its dramatic seasonal shifts in temperature and humidity — untreated timber would have risked warping or misaligning over time. Thermory’s chemical-free modification process delivered the necessary stability, while also providing the natural warmth and sustainability credentials aligned with the project’s net-zero ambitions. 

The result is a facade that not only enhances the iconic geometric form of Powerhouse Telemark but also demonstrates how dimensionally stable, sustainable timber slats can perform at the highest level of architecture. 

Read more

Design Integrity, Delivered 

A timber slat facade is often an architectural statement. With conventional wood, that statement fades as the material shifts over time. With Thermory, dimensional stability ensures that your design looks as good in ten years as it does on day one. 

Explore our facade profiles or connect with our team to specify Thermory for your next project.