A customer once asked me to price the same deck twice — once in Burma teak, once in thermally modified pine. The teak quote was nearly four times higher. He stared at the two numbers for a long moment and asked the only question that matters: "What am I actually paying for?" Fair question. Here's the honest answer.
What teak gives you
Teak earned its reputation. The natural oils inside it repel water and insects without any treatment at all. Ships were decked with it for centuries for a reason. Good teak is durability class 1 — the highest — and it's a genuinely beautiful, dense, golden wood that machines cleanly and ages with dignity.
It's also strong. Unlike thermally modified timber, teak keeps its full structural strength, so you can use it for load-bearing work, boat parts, heavy outdoor furniture that gets dragged around.
The problems are supply and price. Real Burma teak is scarce, plantation teak varies a lot in quality, and the paperwork on origin matters more every year. Prices have gone one direction my whole career: up.
What thermally modified timber gives you
ThermoWood gets to roughly the same destination — wood that survives outdoors — by a different road. Heat treatment instead of natural oils. Thermo-D grade reaches durability class 2, one step below teak, which in practice means a deck that lasts 25-plus years instead of 40-plus.
Where it quietly beats teak is movement. Heat-treated wood swells and shrinks about half as much as untreated timber, and in my experience a thermally modified deck stays flatter through Indian seasons than many hardwood ones. It's also consistent — every board from a batch behaves the same, because it came off the same controlled process. Nature doesn't offer that consistency; kilns do.
And the price: typically a quarter to a third of decent teak for the same coverage.
The side-by-side
| Factor | Teak | ThermoWood (Thermo-D) |
|---|---|---|
| Durability class (EN 350) | 1 — excellent | 2 — very good |
| Realistic outdoor life | 40+ years | 25–30 years |
| Structural strength | Full | Reduced — not for load-bearing |
| Movement in service | Low | Very low |
| Price | High and rising | Moderate |
| Supply and origin paperwork | Complicated | Straightforward |
How I'd decide
Ask yourself three questions.
Will it carry load? If yes — pergola beams, boat work, anything structural — teak or another full-strength hardwood. ThermoWood is out.
How long must it last? If the answer is "longer than I'll own this house," teak justifies itself. If 25 years is enough — and for most decks and cladding it honestly is — thermally modified timber does the job for a fraction of the money.
Does the money matter? If the budget difference between the two would decide whether the project happens at all, that's your answer right there.
What about the other options?
People usually shortlist these two, but three others come up in the same conversation.
Ipe and other dense tropicals sit near teak on durability at a somewhat lower price, but they're brutally hard on tools and the supply-chain paperwork carries the same headaches as teak.
WPC (wood-plastic composite) needs no maintenance at all, which is genuinely attractive — but it gets hot underfoot in the sun, looks like what it is, and can't be sanded back to new the way real wood can.
Chemically treated pine is the cheapest way onto a deck, and you get what you pay for: shorter life, more movement, and chemicals some clients now refuse outright.
Accoya deserves a mention too — acetylated radiata pine that actually beats teak on durability class, with almost no movement, at a price to match. For painted joinery it is superb; for a deck it is usually more wood than the job needs. Full figures on our Accoya data page.
ThermoWood took market share from all three of these for a reason. It sits in the gap they leave.
My verdict
For decking and cladding on a normal budget, thermally modified timber wins on value and nobody who chose it has come back to me unhappy. For heirloom furniture, marine work, or when only that golden teak look will do — pay for teak and don't look back. Both are good materials. They're just good at different jobs.
You can check any species' rating with our free durability class checker, and compare hardness numbers in the Janka database.