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An 8-person sauna is a large installation — the biggest pre-built units available or, more commonly, a custom-built sauna room designed for a specific space and use case. At this capacity, the sauna is either a centerpiece residential feature (a dedicated backyard building, a converted garage, a pool house addition) or a commercial installation for a gym, spa, wellness center, Airbnb, or vacation rental. Eight seats means upper and lower bench tiers on multiple walls, a generous heater with substantial stone capacity, and enough room for groups to socialize, rotate between tiers, and pour löyly without crowding. Pre-built barrel and cabin saunas exist at this size, but the majority of 8-person installations are custom — built to fit the space, the budget, and the intended use.
The largest barrel saunas from SaunaLife and other manufacturers reach 8-person capacity at their maximum lengths (9–10+ feet with a 6–7 foot diameter). At this size, the barrel typically includes a front changing room partitioned from the main sauna room — a practical feature for group use where people enter and exit at different times. SaunaLife's thermally treated wood construction handles year-round outdoor exposure without chemical preservatives.
Large cabin saunas from Auroom, True North, and Dundalk Leisurecraft are available in configurations that seat 8+ people. Cabin saunas offer the most interior flexibility — flat walls for multi-tier L-shaped or U-shaped bench layouts, standard door sizing, and room for a changing area, porch, or cooling space. Browse our luxury saunas collection for the premium end of this range.
For most 8-person installations, custom is the better path. A custom-built room lets you match the sauna to your exact space and requirements — dimensions tailored to the available footprint, bench layout designed for how the sauna will actually be used (a residential family sauna has different layout priorities than a commercial facility), ceiling height optimized for heat stratification, window and door placement for the site, and material selection based on durability needs and aesthetic preferences.
At 8 person, the cost advantage of building custom is significant. Pre-built units at this size carry substantial premiums for factory construction and freight shipping — a structure this large often requires specialized delivery. A custom build using the same or better materials typically costs 20–40% less when you factor in the freight savings and the ability to source materials efficiently for your specific room dimensions.
We carry all the materials for a complete 8-person custom build: sauna wood in western red cedar, Thermory thermowood (thermo-aspen, thermo-spruce, thermo-alder, thermo-radiata pine), hemlock, and natural aspen or alder. Plus glass and wood doors, benches, lighting, vents, vapor barrier, heater guard rails, and accessories. Use our sauna wood calculator to estimate material quantities, our A-Z Custom Sauna Room Guide for a complete build walkthrough, and our custom sauna design and quote service for professional design assistance including floor plans, materials lists, and heater specifications.
An 8-person sauna room is typically 450–700 cubic feet of interior volume. That requires a 12–18 kW electric heater — firmly in the territory of floor-standing heaters with large stone beds rather than compact wall-mounted units. Floor-standing heaters hold 100–200+ lbs of stones, which provides the thermal mass needed for sustained group sessions with frequent and generous löyly pours. At 12+ kW, the heater produces enough energy to recover temperature quickly after a door opening or water pour — critical when eight people are rotating in and out.
All heaters at this size require a 240V dedicated circuit — residential installations use single-phase, while commercial installations may require three-phase power depending on the heater model and local electrical standards. Budget a 50–80 amp breaker and corresponding wire gauge. Use our heater sizing calculator for exact specifications, and browse our electric heaters from Harvia, HUUM, and Saunum. WiFi-controlled heaters are essential at this size — pre-heating a 12–18 kW heater from your phone means the sauna is at temperature when the group is ready, without running it unnecessarily.
Wood-burning stoves are the other option. A large wood-fired stove (18+ kW) with a heavy stone bed delivers the most intense traditional heat and handles rooms this size without any electrical infrastructure — just a chimney and firewood. For off-grid installations, remote properties, or sauna purists, wood-fired is unmatched. Stoves at this size require professional chimney installation and local fire code compliance.
An 8-person sauna is the sweet spot for many commercial applications — large enough for group sessions or back-to-back individual use with high throughput, but not so large that it requires commercial-building-scale mechanical systems. Common commercial use cases include gym and fitness center saunas (member amenity or paid service), spa and wellness center treatment rooms, hotel and resort amenities, Airbnb and vacation rental premium features, and corporate wellness facilities.
Commercial installations require considerations beyond residential: heaters rated for continuous or high-duty-cycle operation, wood species that resist moisture absorption, odor retention, and cleaning chemicals (western red cedar and thermally treated wood are the standards), bench surfaces designed for easy cleaning between users, ADA compliance (32-inch minimum clear door width, low threshold, wheelchair maneuvering space, accessible bench heights, controls within reach), adequate ventilation for high-occupancy sessions, and potentially three-phase power and health department permitting.
For comprehensive commercial planning, read our guides: Saunas for Gyms, Spas & Wellness Centers, Capacity Planning Guide, ADA Compliance for Commercial Saunas, and How to Make Money with a Sauna Business. If you're evaluating the business case for adding a sauna to a commercial space, that last guide covers pricing models, ROI calculations, and revenue projections in detail.
For most buyers, custom is the better value at this size. Pre-built 8-person barrels and cabins are excellent products, but the freight shipping cost for a structure this large can add $1,000–$3,000+ to the total, and you're limited to the manufacturer's dimensions and bench layout. A custom build costs 20–40% less for comparable or better materials and gives you full control over every detail. The exception: if you want a barrel shape specifically (difficult to build custom) or if you don't have the time or labor for a construction project, a pre-built unit is the simpler path. Our custom design service can help you evaluate both options for your specific situation.
Plan for approximately 8×8 to 8×10 feet of interior room dimensions (64–80 square feet of floor area) with a 7-foot ceiling. This provides enough space for upper and lower benches on two or three walls, a floor-standing heater with a safety railing, and adequate clearance for people to move comfortably. If you're including a changing room or anteroom, add 4–6 feet of length. The total footprint of the structure (including walls and exterior) will be roughly 2 feet larger in each dimension than the interior measurements.
A 12–18 kW electric heater running for a 1-hour session (including heat-up) costs approximately $1.80–$3.00 at typical US electricity rates ($0.12–$0.15/kWh). For daily residential use, that's $55–$90 per month. For commercial operations running multiple sessions per day, monthly costs scale accordingly — but so does revenue. Wood-fired stoves offer lower per-session operating costs when firewood is affordable, and the operating cost is fixed regardless of electricity rates. The per-person cost of an 8-person sauna used at capacity is actually very low — $0.25–$0.40 per person per session.
Usually yes, at least for the electrical installation. An 8-person sauna with a 12–18 kW heater requires a 240V dedicated circuit that needs an electrical permit and inspection in virtually all municipalities. The structure itself may require a building permit if it exceeds local square footage thresholds for accessory buildings (often 100–120 sq ft — an 8-person sauna is typically at or above this). Commercial installations have additional requirements: health department review, fire code compliance, occupancy permits, and ADA certification. Start by checking with your local building department — most requirements are predictable and straightforward to meet with proper planning.
Shop more: All Outdoor Saunas · 7-Person Saunas · 6-Person Saunas · Barrel Saunas · Cabin Saunas · Luxury Saunas · Electric Heaters · Wood-Burning Stoves · Custom Sauna Design · Sauna Learning Center
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