The SaunaLife Model S4 is a luxury wood-burning hot tub built for the way people actually use a backyard. Up to 6 bathers, 304 gallons of water, no electricity required, and one of the fastest heat-up times in the wood-fired category. It arrives fully assembled in your choice of finish, S4N (Natural Thermo-Spruce) or S4B (Black-stained Thermo-Spruce), and starts working the moment you fill it and light the stove.
Premium Thermo-Spruce, twice the lifespan of cedar
The exterior is built from durable Thermo-Spruce wood with a 1.65" thick surround, a thermally treated Northern European softwood that lasts up to 2X longer than cedar. Choose the warm natural Thermo-Spruce finish (S4N) for a classic Scandinavian look, or the sophisticated black-stained finish (S4B) for a modern, architectural feel. Both versions deliver identical thermal performance and durability outdoors.
304 stainless steel stove, fast heat-up
At the core of the system is a self-cleaning corrugated wood-burning stove with a secondary heat chamber that transfers heat from the smoke. The result is real efficiency: heat transfer is improved, wood consumption drops by up to 50%, and 304 gallons of water heat from 40°F to 95°F in just 1.5 to 2 hours, the fastest-heating wood-burning hot tub available. The stove also draws cooler water through a lower channel and redistributes it through an upper channel to equalize temperature throughout the tub.
304 gallons, ergonomic for 6 bathers
The interior uses a thick contoured fiberglass insert in dark grey that contours to the body for genuine soaking comfort. With 304 gallons of water capacity and seating for 6, the S4 works equally well for family soaks, evenings with friends, or solo recovery sessions. Ergonomic seating means no awkward shifting to find a comfortable position.
No electricity, ready out of the box
The S4 needs no electrical connection, no plumbing connection, and no contractor for the cabin itself. It ships fully assembled with matching Thermo-Spruce stairs, a polished stainless steel chimney, an insulated folding cover with marine-grade vinyl exterior, and a built-in drainage tap. Position the tub, install the chimney, fill the tub, light the stove, and you're soaking.
Luxury wood-burning hot tub for up to 6 bathers, in your choice of finish (S4N Natural or S4B Black). Premium Thermo-Spruce construction lasting 2X longer than cedar, 304-gallon ergonomic fiberglass interior, self-cleaning corrugated stove that heats from 40°F to 95°F in 1.5 to 2 hours, and zero electricity required. Ships fully assembled with stairs, chimney, insulated cover, and drainage all included.
Wood-burning hot tub Up to 6 persons Natural or Black finish Premium Thermo-Spruce No electricity required 304 gallon capacity Heats in 1.5–2 hours Authorized SaunaLife dealer
Specifications
Dimensions & capacity
| Capacity |
Up to 6 persons |
| Water capacity |
304 gallons |
| Heat-up time |
40°F to 95°F in 1.5 to 2 hours |
| Surround thickness |
1.65" Thermo-Spruce |
Construction & materials
| Exterior |
Thermally enhanced spruce (1.65" thick) |
| Interior |
Contoured fiberglass (dark grey) |
| Stairs |
Matching Thermo-Spruce, included |
| Cover |
Steel-reinforced foam, marine-grade vinyl wrap |
| Drainage |
Built-in tap |
| Origin |
Handcrafted in Northern Europe |
| Wood lifespan |
Up to 2X longer than cedar |
Wood-burning stove
| Design |
Self-cleaning corrugated, secondary heat chamber |
| Water heating |
Super-heated air between fiberglass & wood exterior |
| Water circulation |
Lower-channel intake, upper-channel redistribution |
| Heat-up time |
1.5 to 2 hours (40°F to 95°F) |
| Wood efficiency |
Up to 50% less wood consumption |
| Chimney |
Polished stainless steel |
| Cover |
Steel-reinforced foam, marine-grade vinyl wrap |
Available finishes
| Natural finish |
Model S4N (Thermo-Spruce natural) |
| Black finish |
Model S4B (Thermo-Spruce black) |
| Construction |
Identical between both finishes |
Shipping & installation
| Configuration |
Fully assembled |
| Installation type |
Outdoor |
| Electrical requirements |
None |
| Setup |
Position tub, install stove & chimney, fill, light |
| Model / SKU |
S4N (Natural) or S4B (Black) |
What's included
SaunaLife Model S4 hot tub (fully assembled)
Premium Thermo-Spruce surround (1.65" thick)
Contoured dark grey fiberglass interior
304 stainless steel wood-burning stove
Polished stainless steel chimney
Chimney protective cap
Matching Thermo-Spruce stairs
Insulated folding cover
Marine-grade vinyl cover exterior
Built-in drainage tap
Installation manual
Warranty documentation
Why the SaunaLife S4 stands out
Choose your finish
Same premium tub, two distinct looks. S4N delivers the warm natural Thermo-Spruce grain. S4B offers a sophisticated black-stained finish for modern outdoor spaces.
Premium Thermo-Spruce
Thermally treated Northern European spruce that lasts up to 2X longer than cedar. The 1.65" thick surround provides exceptional insulation for outdoor use.
No electricity required
Wood-burning operation means no electrical hookup, no plumbing, no contractor for the cabin. Position it anywhere outdoors with stove clearance and you're ready.
Self-cleaning corrugated stove
Secondary heat chamber transfers heat from the smoke for up to 50% less wood consumption. Heats 304 gallons from 40°F to 95°F in just 1.5 to 2 hours.
Up to 6 bathers
304-gallon capacity with ergonomic seating means real comfort for the whole family or a group of friends, not just two people squeezed in shoulder-to-shoulder.
Fully assembled delivery
Arrives ready to use with stairs, chimney, insulated cover, and drainage built in. No carpentry, no DIY, no contractor required for the tub itself.
About SaunaLife
European craft, American design
Designed in the U.S., crafted in Northern Europe
SaunaLife was founded by sauna and wellness enthusiasts who wanted to make premium-quality home wellness more accessible. Partnering with Nordic innovators, they leverage Scandinavian design, sustainable materials, and traditional construction techniques to deliver products that actually last. The S4 brings that same philosophy to wood-burning hot tubs.
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Two finish options, S4N (Natural) or S4B (Black)
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Premium Thermo-Spruce, lasts up to 2X longer than cedar
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304 stainless steel stove, dual chambers, fast heat-up
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Ergonomic fiberglass interior, contoured for real comfort
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Limited Lifetime warranty, backed by the manufacturer
About SaunaLife
Wood-fired soaking, the way it should be
SaunaLife uses sustainably sourced, thermally treated Northern European wood across the entire product line, the same standard they apply to their flagship saunas extends to the SOAK Series tubs. Every S4 is precision-crafted before it leaves the factory and built to handle outdoor conditions for years with minimal maintenance.
The result is a wood-burning hot tub that sits naturally in a backyard, deck, or wooded property, looks intentional rather than industrial, and delivers the kind of slow, traditional soaking experience that electric hot tubs can never quite match.
Manuals & Documents
Everything you need before and after installation
Download the official SaunaLife S4 documentation below. Review the installation manual before delivery so you understand the chimney installation and stove operation. The tub itself ships pre-assembled, but the chimney requires installation onto the stove before first use.
Installation & Dimensions
Warranty
Warranty
SaunaLife Limited Lifetime Warranty
Every SaunaLife Model S4 (S4N or S4B) is backed by SaunaLife's Limited Lifetime Warranty on the tub's structural integrity and craftsmanship for residential use, the highest level of protection available in the category. The 304 stainless steel stove is covered under its own manufacturer warranty terms. All warranty claims go directly through SaunaLife with full factory support. Proof of purchase from an authorized dealer is required to start any claim, and we are an authorized SaunaLife dealer. See the official warranty document above for full terms.
