WI-INDEX · version 1.0.0 · released 2026-08-01 · CC BY 4.0
The Wood Intelligence Index
Modelled service life for exposed timber, zone by zone. 288 calibrated model predictions covering 12 species across 6 climate zones, each one a 1200-iteration Monte Carlo run with published uncertainty. These are model estimates, not field measurements — every input, equation and validation result is published below. Open data, free to cite, free to reproduce.
Headline findings
What the model says
- Global median (modelled)
- 21 yr
- Untreated, south-facing, fully exposed cladding — model P50
- Harshest zone
- Singapore
- 14 yr modelled mean across all species
- Kindest zone
- Pacific North-West, USA
- 32.9 yr modelled mean across all species
- Maintenance gain
- +6.9 yr
- Mean modelled gain from a maintained protective system
01
Climate outweighs species choice in the model
The same timber differs by 28 modelled years between the kindest and harshest zone in this index. Acetylated Radiata Pine runs 48 years in Coastal Scotland and 20 years in Singapore. The zone term dominates the species term across every case in the dataset.
02
Warm, humid zones compress every advantage
In Singapore, the best-performing species in the index reaches a modelled 21 years untreated. EN 350 assigns durability classes from defined test conditions and does not itself express service life in years for a given climate — the conversion to years here is this model's, and is calibrated against 24 field cases.
03
Orientation is a design variable, not a detail
Across the indexed zones, switching a façade from south to north changes modelled service life by up to 4.9 years — comparable in magnitude to changing species within the same zone.
Provenance
What this index is built on
Every number above is model output, not observation. It can be reproduced from the published method and the downloadable dataset.
Limits worth stating plainly: the validation set is small (24 cases), correlation under blind testing is moderate (r = 0.56), and zones with no field case behind them are extrapolations. Treat single-figure medians as indicative and use the P10–P90 range for decisions. See the full validation record.
Climate severity ranking
Where wood ages fastest
| Rank | Climate zone | Köppen | Mean service life | Best species | Maintenance gain | North vs south |
|---|---|---|---|---|---|---|
| 01 | Singapore | Af — tropical rainforest | 14 yr | Robinia (Black Locust) · 21 yr | +4.2 yr | +0.4 yr |
| 02 | Riyadh, Saudi Arabia | BWh — hot desert | 17.1 yr | Iroko (FSC certified) · 25 yr | +6.6 yr | +4.9 yr |
| 03 | Dubai, UAE | BWh — hot desert, coastal | 18.5 yr | Iroko (FSC certified) · 27 yr | +5.6 yr | +2.3 yr |
| 04 | Stockholm, Sweden | Dfb — humid continental | 31.8 yr | Robinia (Black Locust) · 45 yr | +8.3 yr | -1.4 yr |
| 05 | Coastal Scotland | Cfb — temperate oceanic | 32.3 yr | Acetylated Radiata Pine · 48 yr | +8.3 yr | -2 yr |
| 06 | Pacific North-West, USA | Csb — warm-summer mediterranean | 32.9 yr | Acetylated Radiata Pine · 47 yr | +8.4 yr | -1.2 yr |
Ranked from harshest to kindest by mean modelled service life across every species in the index, for untreated, south-facing, fully exposed cladding.
Species resilience
Which timbers travel best
| Rank | Species | EN 350 class | Mean across zones | Best zone | Worst zone | Zone sensitivity |
|---|---|---|---|---|---|---|
| 01 | Acetylated Radiata PinePinus radiata (acetylated) | DC 1 (very durable) | 35 yr | Coastal Scotland · 48 yr | Singapore · 20 yr | ±28 yr |
| 02 | Iroko (FSC certified)Milicia excelsa | DC 1–2 (very durable) | 35 yr | Pacific North-West, USA · 47 yr | Singapore · 20 yr | ±27 yr |
| 03 | Robinia (Black Locust)Robinia pseudoacacia | DC 1–2 (very durable) | 34.5 yr | Pacific North-West, USA · 46 yr | Singapore · 21 yr | ±25 yr |
| 04 | Thermally Modified AshFraxinus excelsior (TMT) | DC 1–2 after modification | 33.7 yr | Coastal Scotland · 46 yr | Singapore · 20 yr | ±26 yr |
| 05 | European OakQuercus robur | DC 2 (durable) | 25.5 yr | Pacific North-West, USA · 35 yr | Singapore · 14 yr | ±21 yr |
| 06 | Thermally Modified PinePinus sylvestris (TMT) | DC 2–3 after modification (process dependent) | 25 yr | Coastal Scotland · 34 yr | Singapore · 15 yr | ±19 yr |
| 07 | Sweet ChestnutCastanea sativa | DC 2 (durable) | 25 yr | Pacific North-West, USA · 35 yr | Singapore · 14 yr | ±21 yr |
| 08 | Western Red CedarThuja plicata | DC 2 (durable) | 24.5 yr | Stockholm, Sweden · 33 yr | Singapore · 14 yr | ±19 yr |
| 09 | Siberian LarchLarix sibirica | DC 3 (moderately durable) | 17 yr | Stockholm, Sweden · 23 yr | Singapore · 9 yr | ±14 yr |
| 10 | Douglas FirPseudotsuga menziesii | DC 3–4 (moderately to slightly durable) | 15.2 yr | Pacific North-West, USA · 21 yr | Singapore · 8 yr | ±13 yr |
| 11 | Scots Pine (heartwood)Pinus sylvestris | DC 3–4 heartwood; sapwood DC 5 but treatable | 14.5 yr | Stockholm, Sweden · 20 yr | Singapore · 8 yr | ±12 yr |
| 12 | Norway SprucePicea abies | DC 4 (slightly durable) | 8.2 yr | Stockholm, Sweden · 11 yr | Singapore · 5 yr | ±6 yr |
Full index
Every species, every zone, with uncertainty
| Climate zone | Species | P10 | P50 | P90 | Spread | Maintenance | Confidence |
|---|---|---|---|---|---|---|---|
| Coastal Scotland | Acetylated Radiata Pine | 16 | 48 | 80 | ±135% | 7 yr | 76% |
| Pacific North-West, USA | Acetylated Radiata Pine | 14 | 47 | 80 | ±141% | 7 yr | 77% |
| Pacific North-West, USA | Iroko (FSC certified) | 14 | 47 | 80 | ±141% | 7 yr | 79% |
| Coastal Scotland | Thermally Modified Ash | 13 | 46 | 79 | ±145% | 6 yr | 68% |
| Coastal Scotland | Iroko (FSC certified) | 14 | 46 | 80 | ±145% | 6 yr | 72% |
| Pacific North-West, USA | Robinia (Black Locust) | 13 | 46 | 80 | ±146% | 7 yr | 75% |
| Coastal Scotland | Robinia (Black Locust) | 15 | 45 | 79 | ±143% | 6 yr | 67% |
| Stockholm, Sweden | Robinia (Black Locust) | 15 | 45 | 78 | ±140% | 6 yr | 68% |
| Stockholm, Sweden | Acetylated Radiata Pine | 14 | 45 | 80 | ±148% | 7 yr | 76% |
| Stockholm, Sweden | Iroko (FSC certified) | 14 | 45 | 80 | ±147% | 6 yr | 65% |
| Pacific North-West, USA | Thermally Modified Ash | 13 | 45 | 80 | ±149% | 7 yr | 71% |
| Stockholm, Sweden | Thermally Modified Ash | 11 | 42 | 79 | ±160% | 6 yr | 62% |
| Pacific North-West, USA | Sweet Chestnut | 11 | 35 | 62 | ±147% | 6 yr | 71% |
| Pacific North-West, USA | European Oak | 10 | 35 | 63 | ±151% | 6 yr | 72% |
| Coastal Scotland | Thermally Modified Pine | 10 | 34 | 61 | ±153% | 6 yr | 65% |
| Coastal Scotland | European Oak | 10 | 34 | 60 | ±146% | 6 yr | 59% |
| Stockholm, Sweden | Western Red Cedar | 10 | 33 | 60 | ±153% | 6 yr | 59% |
| Stockholm, Sweden | European Oak | 10 | 33 | 59 | ±150% | 6 yr | 64% |
| Pacific North-West, USA | Thermally Modified Pine | 11 | 33 | 59 | ±143% | 7 yr | 67% |
| Coastal Scotland | Sweet Chestnut | 9 | 32 | 60 | ±158% | 6 yr | 57% |
| Coastal Scotland | Western Red Cedar | 9 | 32 | 57 | ±148% | 6 yr | 56% |
| Stockholm, Sweden | Sweet Chestnut | 9 | 32 | 57 | ±150% | 6 yr | 62% |
| Stockholm, Sweden | Thermally Modified Pine | 9 | 32 | 58 | ±151% | 6 yr | 57% |
| Pacific North-West, USA | Western Red Cedar | 9 | 32 | 60 | ±158% | 6 yr | 67% |
| Dubai, UAE | Iroko (FSC certified) | 9 | 27 | 47 | ±143% | 6 yr | 60% |
| Dubai, UAE | Thermally Modified Ash | 8 | 26 | 47 | ±150% | 6 yr | 52% |
| Dubai, UAE | Robinia (Black Locust) | 8 | 26 | 47 | ±149% | 6 yr | 57% |
| Dubai, UAE | Acetylated Radiata Pine | 8 | 26 | 48 | ±156% | 6 yr | 59% |
| Riyadh, Saudi Arabia | Iroko (FSC certified) | 8 | 25 | 45 | ±146% | 6 yr | 60% |
| Riyadh, Saudi Arabia | Robinia (Black Locust) | 7 | 24 | 43 | ±149% | 6 yr | 57% |
| Riyadh, Saudi Arabia | Acetylated Radiata Pine | 7 | 24 | 45 | ±159% | 6 yr | 59% |
| Stockholm, Sweden | Siberian Larch | 7 | 23 | 41 | ±150% | 6 yr | 67% |
| Riyadh, Saudi Arabia | Thermally Modified Ash | 6 | 23 | 43 | ±157% | 5 yr | 52% |
| Pacific North-West, USA | Siberian Larch | 8 | 23 | 42 | ±147% | 6 yr | 74% |
| Coastal Scotland | Siberian Larch | 7 | 22 | 41 | ±153% | 6 yr | 62% |
| Singapore | Robinia (Black Locust) | 7 | 21 | 37 | ±146% | 6 yr | 57% |
| Pacific North-West, USA | Douglas Fir | 7 | 21 | 37 | ±144% | 6 yr | 63% |
| Coastal Scotland | Douglas Fir | 6 | 20 | 37 | ±157% | 6 yr | 48% |
| Stockholm, Sweden | Douglas Fir | 6 | 20 | 38 | ±154% | 6 yr | 56% |
| Stockholm, Sweden | Scots Pine (heartwood) | 6 | 20 | 36 | ±154% | 6 yr | 52% |
| Singapore | Thermally Modified Ash | 6 | 20 | 35 | ±149% | 6 yr | 52% |
| Singapore | Acetylated Radiata Pine | 5 | 20 | 36 | ±152% | 6 yr | 59% |
| Singapore | Iroko (FSC certified) | 6 | 20 | 37 | ±150% | 6 yr | 60% |
| Pacific North-West, USA | Scots Pine (heartwood) | 6 | 20 | 37 | ±153% | 6 yr | 55% |
| Dubai, UAE | Thermally Modified Pine | 5 | 19 | 34 | ±156% | 6 yr | 49% |
| Dubai, UAE | Sweet Chestnut | 6 | 19 | 33 | ±146% | 5 yr | 52% |
| Dubai, UAE | Western Red Cedar | 5 | 19 | 33 | ±148% | 5 yr | 49% |
| Dubai, UAE | European Oak | 6 | 19 | 34 | ±152% | 6 yr | 54% |
| Coastal Scotland | Scots Pine (heartwood) | 5 | 18 | 34 | ±161% | 5 yr | 46% |
| Riyadh, Saudi Arabia | Sweet Chestnut | 5 | 18 | 32 | ±153% | 5 yr | 52% |
| Riyadh, Saudi Arabia | European Oak | 6 | 18 | 31 | ±146% | 5 yr | 54% |
| Riyadh, Saudi Arabia | Thermally Modified Pine | 5 | 17 | 31 | ±153% | 5 yr | 49% |
| Riyadh, Saudi Arabia | Western Red Cedar | 5 | 17 | 31 | ±150% | 5 yr | 49% |
| Singapore | Thermally Modified Pine | 5 | 15 | 25 | ±136% | 6 yr | 49% |
| Singapore | Sweet Chestnut | 5 | 14 | 25 | ±147% | 6 yr | 52% |
| Singapore | Western Red Cedar | 5 | 14 | 26 | ±151% | 6 yr | 49% |
| Singapore | European Oak | 5 | 14 | 26 | ±149% | 6 yr | 54% |
| Dubai, UAE | Siberian Larch | 5 | 13 | 23 | ±140% | 6 yr | 56% |
| Riyadh, Saudi Arabia | Siberian Larch | 5 | 12 | 22 | ±144% | 5 yr | 56% |
| Stockholm, Sweden | Norway Spruce | 5 | 11 | 20 | ±138% | 5 yr | 48% |
| Riyadh, Saudi Arabia | Douglas Fir | 5 | 11 | 20 | ±133% | 5 yr | 46% |
| Pacific North-West, USA | Norway Spruce | 5 | 11 | 20 | ±140% | 5 yr | 47% |
| Dubai, UAE | Douglas Fir | 5 | 11 | 20 | ±134% | 5 yr | 46% |
| Dubai, UAE | Scots Pine (heartwood) | 5 | 11 | 20 | ±137% | 5 yr | 46% |
| Coastal Scotland | Norway Spruce | 5 | 10 | 19 | ±136% | 5 yr | 46% |
| Riyadh, Saudi Arabia | Scots Pine (heartwood) | 5 | 10 | 19 | ±134% | 5 yr | 46% |
| Singapore | Siberian Larch | 5 | 9 | 17 | ±129% | 6 yr | 56% |
| Singapore | Douglas Fir | 5 | 8 | 15 | ±117% | 5 yr | 46% |
| Singapore | Scots Pine (heartwood) | 5 | 8 | 14 | ±118% | 5 yr | 46% |
| Riyadh, Saudi Arabia | Norway Spruce | 5 | 6 | 11 | ±98% | 4 yr | 46% |
| Dubai, UAE | Norway Spruce | 5 | 6 | 11 | ±97% | 4 yr | 46% |
| Singapore | Norway Spruce | 5 | 5 | 8 | ±54% | 4 yr | 46% |
Specify against P10, not P50. P10 is the value that nine runs in ten exceed; P50 is the central estimate and P90 the optimistic tail. Bands are wide on purpose — the validation benchmark shows narrow bands would be fiction.
For journalists and researchers
Use this, and cite it
The index is published under CC BY 4.0. Reproduce the tables, chart the CSV, quote the findings — the only condition is attribution. Every number here is generated by the published method from published inputs; nothing is hand-edited, and there is no commercial interest in which species or which treatment wins.
Reference case: Vertical cladding, fully exposed, south orientation, untreated, calibrated WI-SL prediction (P50). Method WI-SL v1.2.0, calibration WI-CAL v1.1.0, 1200 Monte Carlo iterations per prediction. These are screening estimates, not guarantees, and should be reported as modelled ranges rather than single figures.
Need a zone, species or building type that is not indexed yet? Ask, and we will run it and publish the result rather than send it privately.
Citation
Wood Intelligence (2026-08-01). WI-INDEX v1.0.0: global timber service-life index. Method WI-SL v1.2.0, calibration WI-CAL v1.1.0. https://woodintel.io/wood-index