Home › Comparison › Forge vs Redwood Outdoors Duo SaunaBox Forge vs Redwood Outdoors Duo (2026): which outdoor traditional sauna is worth it?
By SaunaBox · Published July 27, 2026 · 8 min read
Short answer
The SaunaBox Forge 1-Person is $4,990 and the Redwood Outdoors Duo is $5,899 — but the Forge seats one and the Duo seats two. That is the trade, and it is the first thing to settle. The Forge is $909 less, takes roughly half the ground area, weighs 471.8 lb against 910 lb, and publishes a named heater model, a 220 °F maximum and a 25-minute heat-up time. Redwood publishes none of those three. Buy the Duo if you need two seats. Buy the Forge if you sauna alone, your yard is tight, or you want to know exactly what you are getting before it ships.
These are both outdoor traditional Finnish saunas — real rocks, real steam, 200 °F-plus heat. Not infrared. The question is not which heats better. It is how many seats you actually need, and how much either company will tell you.
The SaunaBox Forge 1-Person. 43.31 x 41.34 x 80.71 in, 471.8 lb, Harvia Vega Compact 3.5 kW heater.
Price gap $909 Forge costs less
Footprint 44% Less ground area
To 170 °F 25 min Forge, from cold
Where these numbers come from. SaunaBox Forge figures are taken from the Forge product page on saunabox.com. Redwood Outdoors Duo figures are taken from the Duo product page on redwoodoutdoors.com, both retrieved on July 27, 2026. Prices and heater options change. Confirm current figures with each manufacturer before ordering.
How do the Forge and the Redwood Duo compare on published specs?
Specification comparison, retrieved July 27, 2026. "Not published" means the manufacturer does not state the figure on its product page.
Specification
Redwood Outdoors Duo
SaunaBox Forge 1-Person
Notes
Price
$5,899
$4,990
Forge is $909 less
Capacity
2 people
1 person
The Duo's clearest advantage
Heater
Choice of Harvia KIP or Spirit 6–8 kW, or Homecraft 9 kW
Harvia Vega Compact BU 3.5 kW model HCBU352401
Forge names one unit; Duo is selected at purchase
Max temperature
Not published
220 °F
Redwood states no figure for the Duo
Heat-up time
Not published
~25 min to 170 °F
From a cold start
Exterior size
62.75 x 50.75 x 82.75 in
43.31 x 41.34 x 80.71 in
~22.1 sq ft vs ~12.4 sq ft of ground
Interior size
Not published
39.37 x 37.80 x 72.83 in
Forge publishes bench and door dimensions too
Weight
910 lb
471.8 lb
Forge is 438 lb lighter
Material
Canadian Thermowood
Canadian hemlock interior, cedar frame, matte black aluminium cladding
Different finishes, both built for outdoors
Electrical
240 V hardwired + 120 V lighting, electrician required
240 V hardwired, 14.4 A, double-pole breaker
Neither plugs in. Both need an electrician
Ventilation
Not published
Active: 1 fan + intake and exhaust vents
Forge publishes fan and vent counts
Warranty
1-year limited heater terms vary
Not published
Confirm with SaunaBox before ordering
Included
Rocks, light fixture, shingles, glass door, felt sauna hat
Rocks, water bucket & ladle, wooden foot stool
Both ship complete
Settle the seat count first
Everything else on this page is secondary to one question: do you sauna alone, or with someone?
If the answer is "with someone", the Duo wins and the $909 is simply what a second seat costs. No amount of published specification makes a one-person cabin fit two people. We are not going to pretend otherwise.
If the answer is "alone" — and for a lot of people buying an outdoor sauna it genuinely is — then you are being asked to pay $909 more for a seat you will never sit in, plus 438 lb of extra weight and nearly double the ground area.
The Forge occupies about 12.4 square feet of ground. The Duo occupies about 22.1. In a large yard that is irrelevant. On a deck, a patio, a side return or a small city garden, it is the entire decision — and it is the reason a one-person outdoor sauna exists as a category at all.
Height is close: 80.71 in against 82.75 in. It is the floor area that differs, not the clearance.
The published-spec gap
Four rows above are marked "not published" for the Duo: maximum temperature, heat-up time, interior dimensions, and ventilation.
For a traditional sauna, the first two are not details. Maximum temperature and heat-up time are the product. A traditional sauna that takes 90 minutes to reach temperature is a different object from one that takes 25, and you cannot tell which you are buying from the Duo's page.
The Forge publishes a Harvia model number you can look up independently, a 14.4 A draw, a 14/2 copper conductor spec, a 70.5–175 cu ft heater capacity rating, and two heat-up figures. You can hand that sheet to an electrician before you order.
A gap on our own side, stated plainly
SaunaBox does not publish a warranty length for the Forge. Redwood publishes 1 year on the Duo. That is a real advantage to Redwood and it is marked as one in the table. If you are comparing these two, ask us for the Forge warranty in writing before you order — the same standard we are applying to Redwood applies to us.
Where the Redwood Duo genuinely wins
Two seats. The single most important difference on this page.
A published warranty. 1-year limited, where SaunaBox publishes none for the Forge.
Heater choice. Harvia KIP, Harvia Spirit with Wi-Fi, or a 9 kW Homecraft, chosen at purchase. The Forge ships with one 3.5 kW unit.
More heater power available. Up to 9 kW against the Forge's 3.5 kW, which matters for a larger cabin volume.
A published assembly estimate , roughly a few hours.
Where the Forge wins
$909 less , at $4,990 against $5,899.
44% less ground area , about 12.4 sq ft against 22.1.
438 lb lighter , 471.8 lb against 910 lb.
220 °F published maximum , where the Duo publishes none.
Published heat-up times , ~25 min to 170 °F and ~40 min to 220 °F from cold.
A named heater , Harvia Vega Compact BU 3.5 kW, model HCBU352401 — Finnish commercial-grade, the same unit used in professional spa installations.
Full interior, bench and door dimensions published , not just the exterior.
Complete electrical spec — 14.4 A, breaker size, wire gauge — so your electrician can quote before it arrives.
A 120 V / 1.9 kW configuration is available on request if a 240 V run is impractical.
Who should buy which?
You sauna with a partner, a friend or a family member, and two seats is non-negotiable. You want to choose your own heater, or you want more than 3.5 kW. A published warranty is a requirement rather than a preference. You have the yard space for a 22 sq ft footprint and the access to move 910 lb into position.
You sauna alone, and a second seat is $909 you would rather keep. Your deck, patio or garden makes 12.4 sq ft the practical limit. You want to know the maximum temperature and the heat-up time before you buy, not after. You want a named heater model you can research independently, and a full electrical spec you can hand to an electrician for a quote.
A note on how we compare
SaunaBox publishes these comparisons and sells one of the two products in them, so treat the framing accordingly. What we can commit to is the method: every competitor figure here is quoted from Redwood Outdoors' own live product page rather than paraphrased, every gap is marked "not published" rather than guessed at, the five places the Duo beats the Forge are listed as plainly as the places it does not, and the one specification SaunaBox fails to publish is flagged against us. If a figure on this page is wrong or out of date, tell us and we will correct it.
Frequently asked questions
Is the SaunaBox Forge an infrared sauna?
No. The Forge is a traditional Finnish sauna. It uses a Harvia Vega Compact 3.5 kW electric heater with sauna rocks and reaches 220 °F, where infrared cabins typically run between 130 and 160 °F. It is built for outdoor installation.
What is the price difference between the Forge and the Redwood Outdoors Duo?
The Forge 1-Person is $4,990. The Redwood Outdoors Duo is $5,899. The Forge is $909 less, but it seats one person where the Duo seats two.
How hot does each sauna get and how fast?
The Forge reaches 220 °F, hitting 170 °F in about 25 minutes and 220 °F in about 40 minutes from a cold start. Redwood Outdoors does not publish a maximum temperature or a heat-up time for the Duo on its product page.
Do both saunas need an electrician?
Yes. Both are hardwired 240 V installations requiring a licensed electrician. The Forge draws 14.4 A on a dedicated double-pole breaker with 14/2 copper conductor. The Duo uses 240 V for the heater and 120 V for lighting. Neither plugs into a standard outlet.
Is the heater included with each sauna?
The Forge includes a specified Harvia Vega Compact BU 3.5 kW heater, model HCBU352401. Redwood offers the Duo with a choice of heater, including Harvia KIP and Spirit at 6 or 8 kW and a Homecraft H-Series at 9 kW, selected at purchase.
How much space does each sauna need?
The Forge measures 43.31 in wide by 41.34 in deep by 80.71 in high, a footprint of about 12.4 square feet. The Duo measures 62.75 in long by 50.75 in wide by 82.75 in high, about 22.1 square feet. The Forge takes roughly half the ground area.
How much do they weigh?
The Forge weighs 471.8 lb assembled and ships as one crate on LTL freight. The Duo weighs 910 lb, roughly 93 percent heavier.
What warranty does each carry?
Redwood publishes a 1-year limited warranty on the Duo, with separate heater terms from Harvia or Homecraft. SaunaBox does not publish a warranty length for the Forge on its product page, so confirm it directly before ordering.
If you need two seats, buy the Duo and stop reading. That is what the extra $909 buys and it is a fair price for it.
If you sauna alone, the Forge is $909 less, takes 44% less ground, weighs 438 lb less, and tells you its maximum temperature, its heat-up time, its heater model number and its amp draw before you spend anything.
One of those two companies is willing to be held to its numbers.
See the Forge
Sources and references
SaunaBox, Forge 1-Person Traditional Finnish Sauna product page . Retrieved July 27, 2026.
Redwood Outdoors, Duo Outdoor Sauna 2-Person product page . Retrieved July 27, 2026.
Harvia, Vega Compact BU electric sauna heater technical documentation, model HCBU352401.
This page is published by SaunaBox, which sells the SaunaBox Forge. Competitor specifications are quoted from the manufacturer's own published product pages and were accurate as of the retrieval date. Nothing here is medical advice. Sauna use may help support recovery and relaxation; it is not a treatment for any condition. Consult a licensed practitioner about your own circumstances.
