Canadian hemlock: why sauna makers use it (and whether it beats cedar)

"Canadian hemlock" appears on almost every infrared sauna spec sheet in the UK — including ours — and almost nobody selling it explains what it is or why it's there. Which is a shame, because the reasons are genuinely good. Here's the story the spec bullet skips.

First: it's a tree, not the poison

Canadian hemlock is the timber of the hemlock tree — Tsuga, a tall conifer from the pine family that grows across Canada and the northern US. No relation whatsoever to poison hemlock, the plant of Socrates fame — that's a parsley cousin. The tree got the name because its crushed needles smell faintly similar. The wood is completely benign.

Why it suits a sauna cabin specifically

It's low-resin. This is the big one. Pines and spruces are full of sticky resin that heat draws to the surface — sap bleed — leaving tacky patches exactly where your bare skin goes. Hemlock has very little resin to bleed, which is why it can face heater panels for years and stay smooth and dry.

It's virtually odourless. Heated hemlock smells of… almost nothing. That sounds like a loss until you sit in a 55°C cabin for 40 minutes. Strongly aromatic woods divide people — what's "spa smell" to one person is a headache to another. Neutral wood means the session smells of clean warmth, nothing else.

It's kind to skin and airways. No aromatic oils means nothing to irritate sensitive skin, allergies or asthma. Hemlock is routinely described as the hypoallergenic sauna wood, and that's a fair label: there's simply very little in it to react to.

It's dimensionally stable. A sauna cabin is a torture test for timber — hundreds of cycles from room temperature to 60°C and back. Hemlock's fine, straight, even grain moves very little through those cycles, so panels stay true, gaps don't open, and doors keep closing properly years in.

It looks the part. Pale, smooth, close-grained, with a clean Scandinavian look that suits a cabin sitting in a spare room rather than a boiler house.

The honest hemlock vs cedar comparison

Western red cedar is the other famous sauna wood, and the industry usually frames it as the "premium" option. The truth is more even-handed:

Cedar's real advantages: those celebrated aromatic oils (the classic cedar scent), naturally strong resistance to moisture and decay — which matters a lot for outdoor saunas in British weather — and a richer, darker look.

Cedar's honest downsides: the same oils that smell wonderful are irritants for a meaningful minority of people — itchy skin, streaming nose, headache at heat. It's also softer, marks more easily, and costs more.

The fair summary: for an outdoor stove sauna getting rained on in Yorkshire, cedar's weather resistance earns its premium. For an indoor infrared cabin — dry heat, no rain, bare skin close to the walls, whole family using it — hemlock's neutrality is a genuine engineering choice, not a cost-cut. It's why we're comfortable that every Kajo cabin is hemlock rather than treating it as something to apologise for.

What to check on any wooden sauna, whatever the wood

Panel thickness and build quality matter more than the species badge. Look for tongue-and-groove or properly jointed panels (not veneered chipboard), a solid bench that doesn't flex, and an interior left unvarnished — sealed wood can't breathe, and coatings have no place against heat and skin.

Curious how the wood fits into the bigger buying decision? Our UK sauna buying guide covers the whole picture, and the Kajo range — full-spectrum infrared in hemlock, from £1,395 — shows where we've landed on it. Questions? WhatsApp us.