Choosing exterior cladding is one of those decisions that affects both the look of a building and how much maintenance you will face for years to come. Two of the most popular timber options in the UK right now are Western Red Cedar and Thermowood. Both deliver a modern, high-quality finish, both work extremely well in shadow gap profiles, and both are widely used on houses, extensions, garden rooms and commercial projects.
They are not the same material, though. They differ in origin, natural durability, appearance, price and how they age. This guide compares them clearly so you can decide which is the better fit for your project.
At Harrogate Flooring we supply both: Western Red Cedar shadow gap cladding and Thermowood pine shadow gap cladding (plus Ayous Thermowood for an even cleaner look). Everything below is based on how these products actually perform in real UK conditions.
What Is Western Red Cedar Cladding?
Western Red Cedar is a naturally durable softwood, mainly sourced from Canada and the north-western United States. It has been used for exterior cladding for decades because of its inherent resistance to decay, insects and moisture.
Key characteristics:
- Attractive natural colour ranging from pinky-red and light brown through to deeper chocolate tones
- Relatively lightweight and easy to work
- Excellent natural durability (typically Class 2)
- Weathers to a soft silver-grey if left unfinished
- Low movement compared with many other softwoods
- PEFC-certified sustainable options widely available
Because the durability is built into the timber itself, Western Red Cedar does not need chemical preservatives. When detailed correctly (good ventilation, correct fixings, proper ground clearance), it can last for many decades with minimal intervention.
It is generally considered a premium cladding choice — both in appearance and in price.
What Is Thermowood Cladding?
Thermowood is timber that has been thermally modified. The process involves heating the wood to high temperatures in controlled conditions with reduced oxygen. This changes the cell structure of the timber, improving dimensional stability and resistance to decay without the use of chemical preservatives.
Most Thermowood cladding sold in the UK is made from pine (often Scandinavian redwood). The heat treatment:
- Reduces the timber’s ability to absorb and release moisture
- Improves stability (less expansion, contraction, cupping and twisting)
- Raises durability, typically to Class 2
- Darkens the colour, giving a richer brown tone
- Makes the wood less attractive to insects and fungi
The result is a more predictable, stable exterior cladding material that performs well in the UK climate and sits at a more accessible price point than Western Red Cedar.
We also supply Ayous Thermowood, which is a lightweight hardwood with a very clean, largely knot-free appearance — ideal when you want a smooth, contemporary look.
Side-by-Side Comparison
| Feature | Western Red Cedar | Thermowood (Pine) |
|---|---|---|
| Origin | North America | Usually Scandinavia / Europe (heat-treated) |
| Natural durability | Excellent | Good to very good (after treatment) |
| Stability | Very good | Excellent |
| Appearance | Rich, varied natural tones | More uniform, warmer brown after treatment |
| Weathering | Attractive silver-grey if left untreated | Also weathers; can be oiled to retain colour |
| Maintenance | Low if left to silver | Low to moderate |
| Cost | Higher | More affordable |
| Weight | Lightweight | Lightweight |
| Knot content | Varies by grade | Depends on grade; clear options available |
| Best for | Premium projects, longevity, classic weathering | Value, modern projects, budget-conscious schemes |
Both materials are suitable for shadow gap, V-groove and other contemporary profiles. Both can look outstanding when installed well.
Appearance and How They Age
Western Red Cedar starts with warm, varied tones. Left unfinished and exposed to the weather, it gradually weathers to a soft, even silver-grey. Many architects and homeowners specifically choose cedar because of this natural ageing process — it looks intentional and high-end rather than neglected.
If you prefer to keep the richer colour, cedar can be treated with oils or UV-protective finishes, though these will need periodic reapplication.
Thermowood emerges from the heat treatment with a deeper, more consistent brown colour. It also weathers if left unfinished, but many people oil it to maintain the richer tone for longer. Because the modification process makes the timber less absorbent, finishes often perform more consistently than on untreated softwoods.
Ayous Thermowood stands out for its clean, even grain and very low knot content. It gives a smoother, more minimal appearance that suits modern architecture particularly well.
Durability and Lifespan
Western Red Cedar has a long track record as an exterior cladding timber. Correctly installed, it routinely delivers decades of service. Its natural oils and extractives contribute to its resistance to rot and insects.
Thermowood achieves comparable durability through thermal modification rather than natural chemistry. The process significantly improves resistance to fungal decay and reduces the timber’s equilibrium moisture content, which helps limit movement and surface checking. In practice, good-quality Thermowood cladding performs very well in UK conditions when detailing is correct (ventilation behind the boards, appropriate fixings, and sensible design at ground level and openings).
Neither material is maintenance-free forever, but both are low-maintenance compared with many painted softwood claddings.
Stability and Movement
This is one area where Thermowood often has an advantage. The heat treatment reduces the timber’s tendency to swell and shrink with changes in humidity. That means less risk of cupping, twisting or large seasonal gaps opening up between boards.
Western Red Cedar is already a relatively stable softwood, which is one reason it has been popular for cladding for so long. Thermowood simply takes that stability further.
For large elevations, south-facing walls, or projects where minimal movement is a priority, Thermowood is frequently the more predictable choice.
Cost and Value
Western Red Cedar is the more expensive option. You are paying for a naturally durable, characterful timber with a strong aesthetic reputation.
Thermowood (especially pine-based) offers a high-quality exterior cladding solution at a lower cost per square metre. For many projects — particularly larger elevations or budget-sensitive schemes — the performance-to-price ratio of Thermowood is very attractive.
Ayous Thermowood usually sits between the two on price, reflecting its cleaner appearance and hardwood classification.
When comparing quotes, always look at the full installed cost and expected lifespan, not just the board price. A slightly more expensive material that needs less maintenance or lasts longer can be better value over time.
Installation Considerations
Both materials are typically supplied in tongue-and-groove form with a shadow gap profile. This allows secret fixing and creates the crisp, contemporary lines that many modern projects want.
Key points for either timber:
- Ensure a ventilated cavity behind the cladding
- Use appropriate stainless or high-quality coated fixings
- Follow manufacturer guidance on expansion gaps and fixing centres
- Detail carefully at windows, doors, corners and ground level
- Consider the orientation of the building and local exposure
Because both Western Red Cedar and Thermowood are relatively lightweight, they are straightforward to handle on site compared with denser hardwoods.
Which Should You Choose?
Choose Western Red Cedar if:
- You want a premium, naturally durable timber
- You like the idea of the boards weathering to silver-grey
- Budget allows for a higher-specification material
- You want a classic, widely recognised high-end cladding look
Choose Thermowood pine if:
- You want excellent stability at a more accessible price
- You prefer a consistent modern appearance
- The project involves larger areas where cost matters
- You value thermal modification over natural durability chemistry
Consider Ayous Thermowood if:
- You want a very clean, largely knot-free surface
- A smooth, minimal contemporary look is the priority
- You still want the stability benefits of thermal modification
There is no single “best” answer — only the best answer for your particular project, budget and aesthetic goals.
Our Exterior Cladding Range
At Harrogate Flooring we supply:
- Western Red Cedar Shadow Gap Cladding – naturally durable, beautiful colour variation, long lifespan
- Pine Thermowood Shadow Gap Cladding – heat-treated for stability and durability, excellent value
- Ayous Thermowood Shadow Gap Cladding – lightweight, clean grade, contemporary appearance
All are available with nationwide delivery from our Yorkshire workshop. Face widths are typically offered in popular sizes (including 78mm and 124mm options depending on the product), with tongue-and-groove shadow gap profiles designed for a smart, modern finish.
Final Thoughts
Western Red Cedar and Thermowood are both strong choices for exterior cladding in the UK. Cedar brings natural durability and a distinctive weathering character. Thermowood brings enhanced stability, consistent appearance and better value for many projects.
The most reliable way to decide is to see and feel the boards. Order samples of both, view them in the actual light of your building, and consider how you want the elevation to look in five or ten years’ time as well as on day one.
If you would like help choosing between Western Red Cedar, Thermowood pine or Ayous Thermowood for a specific project, get in touch. We are happy to advise on suitability, quantities and detailing.
Related products:
Western Red Cedar Shadow Gap Cladding
Pine Thermowood Shadow Gap Cladding
Ayous Thermowood Shadow Gap Cladding
Full Exterior Cladding Collection
Harrogate Flooring – Quality timber flooring and exterior cladding, supplied from Yorkshire, delivered nationwide.