Leil Saunas Black Cube Premium - 4 Person Outdoor Traditional Sauna Kit
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An Important Note on Pricing and Returns:
We believe in upfront pricing and fair policies—no hidden fees, no surprises, and easy,
transparent returns. If you're comparing options, we encourage you to review
competitors’ fine print carefully.
We've helped countless customers who had issues elsewhere, and we’re here to make sure
that never happens to you.
Starts at: $2,497.50/mo Learn More
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Monthly payments start at: $2,497.50/mo Learn More
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LEIL BLACK CUBE PREMIUM
4-Person Outdoor Sauna Kit
Compact footprint. Elevated interior experience.
The Black Cube Premium is a refined 4-person outdoor sauna designed for those who want modern Nordic architecture paired with a more elevated interior finish. Its compact footprint makes it ideal for residential backyards while still delivering a full, immersive sauna experience for small groups.
Built from 40mm thermo-treated pine and finished in a bold black exterior, it combines durability with striking design. Inside, the Premium model introduces a signature hexagon decorative wall and opposing alder wood benches for a more social, face-to-face layout. The full glass front enhances openness while maintaining strong heat retention for electric heater setups only.
A compact sauna, elevated into a design statement.
Minimal footprint. Maximum refinement inside.
The Black Cube Premium was designed around a simple idea: a smaller sauna should still feel like a premium architectural space. Instead of scaling down the experience, it refines it—bringing together bold exterior geometry and a more curated interior layout built for comfort, conversation, and daily use.
From the outside, it carries the signature Black Cube identity with its dark thermowood shell, full-circle arches, and expansive glass front. But stepping inside reveals a different intention: a more intimate, design-focused environment featuring a hexagon decorative wall and opposing alder wood benches that naturally encourage shared sessions without crowding the space.
Every detail is tuned for modern outdoor living—efficient electric heating, controlled airflow through integrated ventilation, and durable 40mm construction built to withstand year-round exposure. It’s not just a sauna you place in your backyard—it’s one you design your space around.
- Premium hexagon interior wall design exclusive to this model
- Opposing alder bench layout for a more social 4-person experience
- 40mm thermo-treated pine exterior for year-round outdoor durability
- Full glass front with electric heater compatibility for clean modern use
Technical Specifications
Every measurement, every material, every rating — in full detail.
Which heater fits the Black Cube — Harvia or HUUM?
HUUM DROP 6 kW
Included in Select Packages- Best for: Standard back wall construction (no panoramic window)
- Output: 6 kW — ideal for the Black Cube's 5 m³ volume
- Control: UKU Classic Wi-Fi controller included
- Style: Minimalist drop-shaped design with large stone capacity
- Why it works: The DROP's stone basket holds more rocks than comparably sized heaters, producing a softer, more even löyly (steam). Wi-Fi control via the HUUM app lets you preheat remotely.
HUUM DROP 9 kW
Recommended — Half-Panoramic Window- Best for: Black Cube with optional half-panoramic back wall window
- Output: 9 kW, accounts for additional heat loss from the panoramic glass
- Control: UKU Classic Wi-Fi controller included
- Style: Same drop design, larger capacity
- Why it works: The panoramic window adds significant glass area. The 9 kW ensures the sauna reaches and holds target temperature even in colder climates without overworking the heater.
Harvia KIP80W (8 kW)
Reliable Alternative- Best for: Buyers who want a simple, proven electric heater
- Output: 8 kW — balanced performance for this sauna size
- Control: Built-in controls (wall-mounted optional upgrade)
- Style: Traditional wall-mounted steel heater design
- Why it works: A dependable, no-frills option from a long-standing Finnish brand. Heats consistently, installs easily, and is ideal if you prefer straightforward operation over app-based control.
Will it fit your space? We’ll help you plan it right.
Share your patio, deck, or backyard measurements and we’ll map out exactly how the Black Cube Premium fits— including clearance zones, door swing, and ideal placement for ventilation and electric heater safety. No guesswork before delivery.
Two people. Weekend build.
The Black Cube Premium arrives as a pre-cut, pre-labeled outdoor sauna kit designed for streamlined DIY assembly. Most of the structure can be completed with standard tools, while the final electrical connection must be completed by a licensed professional.
Two people, a drill, a level, and basic hand tools. No specialized equipment required.
What’s in the Kit
Every component is pre-cut, labeled, and precision-engineered for modular assembly. All hardware and installation documentation are included to ensure a smooth build process.
- 40mm Thermowood wall panels, base frame, and roof structure
- Black shingle roof system for full weather protection
- 8mm black tempered glass front wall and door assembly
- Two-level Alder wood benches (opposing layout with backrests)
- Hexagon decorative interior wall panel (Premium-exclusive feature)
- Nerostep anti-slip plastic grid floor mats
- Full-circle front and rear arch panels (painted black)
- Integrated ventilation system (3–4 air openings)
- All fasteners, mounting hardware, and step-by-step manual
Assembly Steps
Prepare a Level Foundation
Install on a stable, level surface such as concrete, reinforced decking, or compacted gravel. Ensure proper drainage and maintain clearance on all sides for ventilation and long-term structural stability.
Unpack & Verify Components
Carefully unpack all labeled parts and cross-check them against the included inventory list before starting assembly to ensure nothing is missing or damaged during transport.
Assemble Base, Walls & Roof Structure
Build the base frame first, then mount the thermo-treated pine wall panels in sequence. Install the roof structure and secure the black shingle system for complete weather protection and insulation.
Install Glass, Interior & Benches
Fit the 8mm black tempered glass front wall and door system, then install the opposing alder wood benches, hexagon decorative wall panel, ventilation covers, and floor grid system.
Licensed Electrician Connects Heater
The electric sauna heater requires a dedicated 240V connection with correct breaker sizing based on the selected unit. This step must be completed by a licensed electrician in accordance with local electrical codes and manufacturer requirements.
Initial Heat Cycle & Break-In
Run the first heating cycle with light ventilation to allow materials to settle. A mild natural wood scent is normal and will fade after initial use cycles.
Yes, it runs on 240V —
built for modern electric heating.
The Black Cube Premium uses a standard residential 240V hardwired electric sauna heater system, similar to high-power appliances like an oven or electric dryer. Depending on your selected heater size (typically 6 kW–9 kW), the system requires a dedicated 20–40 amp circuit. A licensed electrician can usually complete installation in 1–2 hours.
From our warehouse to your driveway.
The moment you order, your concierge rep is assigned and your shipment starts moving. We monitor every stage so you don't have to. Fully insured, with a scheduled delivery appointment so nothing arrives when you're not home.
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Good luck getting
Costco on the phone.
Most $8,000 purchases come with a phone tree. Ours comes with a person. When something goes sideways — a lost shipment, a freight delay, a damaged panel, a question at 9 PM on a Wednesday — you text us. We text back. Same day, often the same hour. We call the manufacturer. We chase the freight company. We solve the problem while you go on with your life. That's what we mean by boutique concierge service. It's the difference between buying a sauna and being supported through one.
Lost in Transit
If your shipment goes missing, we're on the phone with the freight carrier before you even know there's a problem. You don't chase anyone. We do.
Shipping Delays
You hear about delays from us, before you wonder. We monitor every shipment, every day, until it's in your driveway.
Manufacturer Defect
If a panel arrives damaged or a heater malfunctions, we escalate directly to Leil, HUUM, or Harvia on your behalf. You don't make a single warranty call. We handle the back-and-forth.
A Question at 9 PM
Text us. Email us. Call us. You get a real answer from a real person — not a chatbot, not a ticket number, not a 48-hour response window.
We're not the cheapest box on the internet. We're the team that picks up the phone after the box is in your driveway. That's what we stand behind — every order, every customer, every day.
Call (605) 702-4868Yes, it's outdoor rated. Built for year-round performance.
Yes. The Black Cube Premium is fully engineered for permanent outdoor installation and designed to withstand all-season exposure. Rain, snow, humidity, and temperature fluctuations are accounted for in its construction. The structure is built to remain stable and weather-resistant without the need for annual sealing or seasonal refinishing, while maintaining consistent sauna performance inside the cabin.
Thermally treated pine resists moisture absorption, warping, and decay. It remains dimensionally stable in outdoor environments and requires no chemical treatment or periodic sealing.
Durable bitumen shingle roofing shields the sauna from rain, UV exposure, and snow load, ensuring long-term protection in exposed outdoor conditions.
The sauna is lifted from direct ground contact, reducing moisture exposure and allowing proper airflow beneath the structure for long-term stability.
Engineered joinery allows the structure to naturally expand and contract with seasonal temperature changes without compromising alignment or sealing.
Integrated airflow openings maintain natural circulation without fans or electronics, ensuring consistent heat distribution and long-term outdoor reliability.
Alder wood benches, tempered black glass, and heat-resistant interior architecture are designed for high temperature and humidity cycles without deterioration over time.
Engineered for durability. Refined for comfort.
The Black Cube Premium is built using a dual-wood construction system designed specifically for outdoor sauna performance. Thermowood forms the structural shell for long-term durability in harsh environments, while Alder is used for all interior contact surfaces to deliver a smooth, comfortable, and heat-safe sauna experience. Together, they balance architectural strength with interior refinement.
Thermowood — 40mm Structural Shell
The exterior walls, roof framework, and base structure are made from thermally modified pine. This process enhances dimensional stability by reducing moisture content and improving resistance to rot, warping, and fungal growth. It ensures the sauna remains structurally stable in year-round outdoor conditions without chemical treatment.
Alder — Interior Comfort Surfaces
All benches and interior seating are crafted from kiln-dried Alder, chosen for its low heat conductivity and smooth surface texture. It stays comfortable to the touch even at high sauna temperatures, making it ideal for extended use in a compact 4-person layout.
Premium Exterior Black Finish
External arches, trim elements, and base accents are finished with a durable black protective coating system. This layer protects against UV exposure, rain, and seasonal weathering while maintaining the Black Cube’s signature modern architectural look.
All-Season Structural Stability
The wood system is designed to handle temperature swings, humidity changes, and freeze-thaw cycles without losing alignment or strength. Combined with proper ventilation and an elevated base, it ensures long-term performance with minimal maintenance requirements.
Open the crate. Everything is pre-cut, pre-labeled, and premium finished.
The Black Cube Premium ships as a complete modular sauna kit designed for efficient DIY assembly. All structural components are precision-cut and labeled for straightforward installation. Heater and electrical components vary based on configuration selected at checkout.
Thermowood Structural Kit
40mm thermo-treated pine panels for walls, roof structure, base frame, and support elements — all pre-cut, labeled, and engineered for outdoor durability.
Electric Sauna Heater (Selected Model)
Compatible with 6 kW–9 kW electric heaters depending on configuration. Includes sauna stones and mounting accessories (controller included where applicable).
Alder Bench System
Premium Alder wood opposing bench layout designed for 4-person seating comfort, including backrests, skirts, and precision-fit supports.
Complete Hardware Pack
All fasteners, screws, bolts, washers, steel bands, ventilation covers, and sealing materials required for full outdoor assembly.
Black Tempered Glass System
8mm black tempered glass front wall and door assembly with premium handle set and matching black-framed architectural finish.
Installation Manual & Layout Guide
Detailed step-by-step assembly instructions including labeled diagrams, foundation guidance, ventilation setup, and electrical overview.
Premium Interior Finish Components
Exclusive hexagon decorative wall panel (Premium model only), interior trim elements, and refined finishing details for a luxury sauna interior.
Frequently Asked Questions
Everything you need to know before ordering your sauna.
Exterior: 86.2" W × 65.4" D × 86.6" H.
Wall thickness: 40mm thermowood.
Interior volume: approximately 5.0 m³.
Manuals & Resources
Everything you need for assembly, electrical, and ongoing maintenance — in one place.
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