Quick Answer: Thermory and Redwood Outdoors both sell backyard barrel saunas built from thermally modified wood instead of cedar, but they’re sized for different buyers. Thermory keeps it simple — two series, $5,066-$7,492, all thermally modified Nordic spruce, shipped from a Buffalo, NY-area warehouse. Redwood Outdoors spreads across at least seven shapes, from a $4,999 Mini Cube to an $11,974 glass-walled Panorama, with a warranty that changes depending on which heater you configure. The honesty-hook: Thermory is the company that actually developed the thermal-modification process the whole industry uses, while Redwood Outdoors is a downstream buyer of that same category of treated lumber under its own brand name, “Thermowood.”
Both brands already show up individually on this site — our Thermory sauna review and Redwood Outdoors sauna review each note the other brand in passing as a competitor in the non-cedar barrel-sauna space. Neither page puts the two side by side, which is the obvious next question for anyone comparing barrel saunas that explicitly aren’t cedar.
Thermory vs. Redwood Outdoors, side by side
| Model | Capacity | Wood | Price |
|---|---|---|---|
| Thermory 50 Series | 4-6 person (3 lengths) | Thermally modified Nordic spruce | $5,066-$6,935 |
| Thermory 60 Series | Larger, 7+ ft headroom | Thermally modified Nordic spruce | $6,797-$7,492 |
| Redwood Mini Cube | 1-2 person | Thermowood | From $4,999 |
| Redwood Thermowood Cabin | 4 person | Thermowood | From $7,299 |
| Redwood Panorama | 6 person | Thermowood, panoramic glass | $6,599-$11,974 |
Thermory — the wood-treatment source, kept to two sizes
Thermory 50 Series Barrel Sauna
- Thermory AS is the Estonian company that developed the thermal-modification process now used across much of the sauna-lumber industry — per our Thermory sauna review, it's also the parent company behind Auroom, the glass-walled cabin brand.
- Just two series (50 and 60), both built from thermally modified Nordic spruce, both shipping flat-floor kit and rain jacket included from a US warehouse near Buffalo, NY.
- No glass-wall option, no heater-dependent warranty split to track — the simplicity is itself the differentiator against Redwood's sprawling catalog.
Redwood Outdoors — more shapes, a warranty that depends on your heater
Redwood Outdoors Thermowood Cabin (4-Person)
- Garage Gym Reviews measured this specific model reaching 190°F in 35 minutes and scored it 5-out-of-5 for heating performance, per our Redwood Outdoors review — one of the few models in this comparison with independently published, measured results rather than a spec sheet alone.
- At least seven shapes across the current catalog (Mini Cube, Duo, Cove, Thermowood Cabin, Barrel, Extra-Wide Barrel, Panorama, Garden), spanning $4,999 to $11,974 — a far wider spread than Thermory's two-series lineup.
- Warranty length actually changes with heater choice on at least one model (the Duo): the standard Harvia heater nets 5 years on the cabin but only 1 year on heating elements, while a Homecraft heater upgrade swaps that for a flat 2-year limited warranty.
The wood: source technology vs. a downstream buyer of the same category
Both brands reject cedar for the same underlying reason — thermal modification swaps cedar’s natural rot-resistant oils for a heat-treatment process that doesn’t rely on chemicals, and as a side effect strips out the compounds behind “cedar sensitivity” some users react to. But the two brands sit at different points in that supply chain. Thermory is the company that actually developed and still supplies the thermal-modification technology to much of the sauna-lumber market, per its own materials. Redwood Outdoors calls its material “Thermowood” and, on at least one model (the Duo), uses heat-treated hemlock instead — Redwood is a brand buying into the same category of treated wood, not the source of the process itself. Neither is a downgrade from the other; it’s the difference between a manufacturer and a brand sourcing from that manufacturer’s category of product.
Catalog size: two sizes vs. a fast-expanding seven-plus
Thermory’s restraint is deliberate — the 50 and 60 Series cover the barrel-sauna use case without a glass-wall tier, a porch tier, or a garden tier to choose between. Redwood Outdoors has gone the opposite direction: per our Redwood Outdoors review, the brand has kept adding full-glass-back-wall models (Vista, Horizon) on top of an already seven-model catalog, and that catalog was still expanding as of this writing. More choice isn’t automatically better — a buyer who wants a straightforward decision will move faster with Thermory’s two sizes than with Redwood’s seven-plus shapes and heater-dependent warranty terms to compare.
Which one fits you
- You want the simplest decision: Thermory’s two-series lineup (50 or 60) gets you to a purchase faster, with no heater-dependent warranty fine print to track down.
- You want the independently-tested option: Redwood’s Thermowood Cabin is the only model in this comparison with a published, measured heat-performance test (190°F in 35 minutes, Garage Gym Reviews).
- You want a glass-wall view: only Redwood offers it, in the Panorama tier ($6,599-$11,974) — Thermory’s own lineup has no glass-wall option.
- You’re deciding between thermally modified wood and cedar at all: read our best barrel sauna roundup first, which covers both this pair and the cedar competitors (Dundalk, Almost Heaven, ALEKO) side by side.
The bottom line
Thermory and Redwood Outdoors both avoid cedar in favor of thermally modified wood, but that’s close to where the similarity ends. Thermory is the simpler, source-technology brand: two sizes, $5,066-$7,492, no catalog sprawl. Redwood Outdoors is the wider, faster-growing catalog: at least seven shapes from $4,999 to $11,974, with a warranty that can change depending on which heater you configure at checkout. Pick Thermory for a fast, simple decision; pick Redwood if you want more shape options or the only independently-tested model in this comparison — just confirm the warranty terms for your specific configuration before ordering either one.