Thermally Modified Siberian Larch VS Thermally Modified Larch
- Harder wear surface (Janka 1100 vs 530 lbf)
- Easier to machine and fasten
- Lighter (0.55 vs 0.59 g/cm³)
- Solid choice where its profile fits the project
Visual comparison
Winner by category
There isn't one universally best wood — there's a best wood for each purpose.
| Category | Winner |
|---|---|
| Durability | Tie |
| Stability | Tie |
| Hardness | Thermally Modified Siberian Larch |
| Strength (MOR) | Thermally Modified Siberian Larch |
| Stiffness (MOE) | Thermally Modified Siberian Larch |
| Flame spread | Tie |
| Machining ease | Thermally Modified Larch |
| Lightness | Thermally Modified Larch |
Engineering data
| Property | Thermally Modified Siberian Larch | Thermally Modified Larch |
|---|---|---|
| Janka Hardness | 1100UNV lbf | 530UNV lbf |
| Density | 0.59ITWA g/cm³ | 0.55ITWA g/cm³ |
| MOE | 11.5ITWA GPa | 11.0ITWA GPa |
| MOR | 78.0ITWA MPa | 75.0ITWA MPa |
| Durability | Class 2 Durable (treated) | Class 2 Durable (treated) |
| Stability | Moderate | Moderate |
| Fire (E84) | Not classified | Not classified |
| Radial Shrink | 1.4ITWA % | 1.3ITWA % |
| Tangential Shrink | 2.9ITWA % | 2.8ITWA % |
| T/R Ratio | 2.07 | 2.15 |
Figures carry the same source status as the species pages they come from — verified where cited, indicative where marked.
Best for
| Application | Recommended | Suitability |
|---|---|---|
| Outdoor decking / pergola | 🥇 Thermally Modified Siberian Larch | ★★★☆☆ |
| Exterior cladding | 🥇 Thermally Modified Larch | ★★★☆☆ |
| Flooring / wear surfaces | 🥇 Thermally Modified Siberian Larch | ★★☆☆☆ |
| Furniture / interior joinery | 🥇 Thermally Modified Larch | ★★★☆☆ |
| Structural / load-bearing | 🥇 Thermally Modified Siberian Larch | ★★☆☆☆ |
Advantages & limitations
Thermally Modified Siberian Larch
Advantages relative to Thermally Modified Larch
- Janka is 1,100 lbf vs 530 lbf, about 2.1× harder
Limitations relative to Thermally Modified Larch
Thermally Modified Larch
Advantages relative to Thermally Modified Siberian Larch
Limitations relative to Thermally Modified Siberian Larch
- Janka is 530 lbf vs 1,100 lbf, about 52% lower
Recommendation
Choose Thermally Modified Siberian Larch if…
- Exterior cladding, rain screens, decking and flooring where the higher dent resistance is what the piece must deliver and the shared Class 2 thermally modified profile is the baseline
- Garden structures and interior panelling where hardness is the deciding property between the two closely related Larix species
Choose Thermally Modified Larch if…
- Exterior cladding and rain screens where the working softer profile is acceptable and either Larix species performs comparably on bending strength and stiffness
- Decking and interior panelling where cost or availability is the deciding factor and the shared thermally modified profile is the specification
Frequently asked questions
Which is more durable, Thermally Modified Siberian Larch or Thermally Modified Larch?
Neither — both carry the same EN 350 rating (Class 2, Durable (treated)). Outdoors, movement will not separate them either — 2.9% against 2.8% tangential. The practical difference is weight: Thermally Modified Siberian Larch runs 0.59 g/cm³ against 0.55, so Thermally Modified Larch is the easier fix overhead and the cheaper one to freight.
Which wood is better for outdoor use?
Both are EN 350 Class 2, and tangential movement runs 2.9% for Thermally Modified Siberian Larch against 2.8% for Thermally Modified Larch — close enough that decay resistance will not choose between them, and Thermally Modified Larch holds its dimension marginally better. Thermally Modified Siberian Larch gives the harder wearing surface at 1,100 lbf; Thermally Modified Larch is the lighter section at 0.55 g/cm³ — traffic favours the first, cladding and handling the second.
Is Thermally Modified Siberian Larch harder than Thermally Modified Larch?
Yes — Janka 1100 lbf vs 530 lbf.