Larch vs Pine vs Thermowood Decking: Which to Choose?
When choosing decking boards, buyers usually compare three materials: Siberian larch, pressure-treated pine and thermowood. All three can work outdoors, but they differ in price, moisture resistance, maintenance and appearance.
We sell Siberian larch only. Pine and thermowood are included for comparison.
Quick comparison
| Criteria | Siberian larch | Treated pine | Thermowood |
|---|---|---|---|
| Price | Mid-range | Usually lowest | Often highest |
| Moisture resistance | Natural (heartwood) | Only after treatment | After heat treatment |
| Hardness | Hard | Softer | Medium, but more brittle |
| Maintenance | Periodic oiling or natural grey | Usually the most demanding | Periodic oiling or natural grey |
| Appearance | Warm, strong grain | Lighter | Even, dark |
| Stability | Good | Most prone to cracking if poorly dried | Most stable |
Siberian larch
Siberian larch heartwood is dense and naturally resistant to moisture and rot. For ventilated, above-ground construction, chemical impregnation is not required. The colour is warm reddish-brown and turns silver-grey outdoors if left untreated. The wood is hard and resists mechanical wear.
Downsides: it costs more than pine, moisture movement can cause small surface checks, and resin pockets may bleed. BC grade has more knots and colour variation.
Pressure-treated pine
Pine is the cheapest of the three. Its moisture resistance comes from treatment, so check the treatment class (usually UC3 for decking, UC4 for ground contact) and the product used. Pine is softer than larch and scratches more easily.
If poorly dried or installed, it can crack and warp more. It usually needs more frequent oiling or staining.
Thermowood
Thermowood is modified with high heat. This makes it more moisture-resistant and more dimensionally stable, with an even, dark brown colour. Its resin content is significantly reduced; it machines cleanly but is more brittle.
Choose fixing distances carefully and do not over-tighten screws. It is usually more expensive, and without protection its colour gradually fades to grey.
Which to choose for your situation
- Tight budget and a large area: treated pine, if you are willing to maintain it regularly.
- Heavy use and less chemical treatment: Siberian larch.
- A modern, even dark look and stability: thermowood, with attention to fixing distances.
- A terrace near water or in a damp spot: ventilation under the boards and the correct slope matter more than the material.
Important
Lifespan depends not only on the material but on installation, ventilation, slope and maintenance. No wood can guarantee a specific service life.
Frequently asked questions
Is larch better than pine for decking?
Larch is naturally more moisture-resistant and harder, so it usually keeps its appearance longer, but it costs more. Treated pine is an economical choice if you accept regular maintenance.
Is thermowood suitable for outdoor decking?
Yes, provided the fixing distances and protection are right. It is stable and evenly coloured, but can be more brittle than larch.
Does larch need oiling?
Not necessarily. Untreated larch turns grey. Oiling helps keep the colour and can reduce surface checking, but it is not required.
Which material is best near water?
Ventilation under the boards and the slope matter more than the material. Even resistant wood suffers when water stands.
What do you sell?
We sell Siberian larch decking boards, kiln-dried (KD) to 16% ±2% moisture.
Links
Decking boards (catalogue) · Installation guide · 24×140×4000 mm larch board