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Finnish Sauna Builders

Carbon Smart™ 3' x 4' x 8' Thermo Poplar Indoor Sauna Room Kit

From $5,190.50

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Product Information
Create a true traditional sauna in a compact footprint with the Carbon Smart™ 3' x 4' x 8' Indoor Sauna Room Kit. This pre-cut Thermo Poplar interior package is designed for homeowners, contractors, spas, and wellness spaces that want a premium custom sauna without sourcing every interior component individually.

Built for a 3' x 4' room with an 8' ceiling, this compact sauna is ideal for personal use or intimate two-person sessions. Select your preferred bench configuration, optional finishing upgrades, and heater package to create a sauna that fits your space and routine.

IMPORTANT: This is a DIY sauna interior kit, not a freestanding prebuilt sauna. You will provide the framing, insulation, electrical wiring, and exterior wall covering. Heater installation and electrical work should be completed in accordance with local codes.

WHY YOU'LL LOVE IT

•Pre-cut sauna interior components tailored for a 3' x 4' x 8' room
•Premium Thermo Poplar interior with rich natural color and improved dimensional stability
•Custom 20" deep bench configuration for a comfortable, space-efficient layout
•All-glass sauna door creates an open, modern look

Foil vapor barrier, ventilation grills, duckboard flooring, lighting, and sauna accessories included
Optional bench skirting and under-bench LED lighting upgrades available
Choose no heater or add a WiFi-enabled Harvia or HUUM heater package

THERMO POPLAR CONSTRUCTION

Thermo Poplar is thermally modified at approximately 374°F using a chemical-free process. The result is a sauna-ready wood with improved resistance to humidity and temperature changes, excellent dimensional stability, and a warm, refined appearance.

HEATER OPTIONS

•No Heater — Ideal if you already have a compatible heater or prefer to source one separately
•Harvia KIP45W 4.5kW WiFi Heater — WiFi-enabled control, heater stones included, no protective railing
•HUUM Cliff Mini 3.5kW WiFi Heater — WiFi-enabled control, heater stones and protective railing included

ACCESSORY PACKAGE OPTIONS

•No Accessories
•Bench Skirting
•LED Under-Bench Lighting
•Luxury Package — Bench Skirting + LED Under-Bench Lighting

Specifications
•Sauna room dimensions — 3' W x 4' D x 8' H

•Approximate interior volume — 96 cubic feet

•Recommended ceiling height — 8'

•Interior wood — Thermo Poplar

•Wall and ceiling boards — 1 x 4 tongue-and-groove Thermo Poplar

•Bench material — Clear 1 x 4 Thermo Poplar with supports

•Bench depth — 20"

•Door type — All-glass sauna door with wood handles and trim

•Door frame dimensions — 27.2" W x 78.7" H

•Glass dimensions — 24.4" W x 77.3" H

•Door frame thickness — 1.65" x 3.6"

•Required rough opening — 28" W x 80" H

•Wall board direction — Horizontal

•Lighting — Marine-grade, wall-mount, vapor-proof sauna light

•Ventilation — Upper and lower vent grills

What's Included
WHAT'S INCLUDED

•Foil vapor barrier
•Ergonomic backrests
•Thermo Poplar tongue-and-groove wall and ceiling boards
•Custom-built 20" deep Thermo Poplar bench boards and supports
•Thermo Poplar corner moldings for walls, ceiling, and baseboards
•All-glass sauna door with wood handles and trim
•Thermo Poplar duckboard flooring for the walk area
•Upper and lower vent grills
•Traditional sauna bucket with liner and ladle
•Sauna thermometer
•Headrest
•Marine-grade vapor-proof wall light
•Detailed installation instructions

WHAT YOU WILL NEED TO PROVIDE

•Wall framing
•Insulation
•Electrical wiring and electrical installation
•Exterior wall covering
•Heater, unless a heater option is selected
•Professional installation support when required by local code

IMPORTANT NOTES

•The shipment includes an all-glass sauna door. Some product images may show a glass wall for reference only.
•Backrests ship flat. On-site spacers can be added if you prefer an angled backrest.
•Confirm room measurements, electrical requirements, and heater installation requirements before ordering.
•This product is made for an indoor sauna-room buildout and requires site preparation before installation.

Questions Before Ordering?

Call 1-877-477-2853 Monday–Friday, 9am–6pm ET, or send us a message. We can help verify fit, compatibility, delivery requirements and warranty details.

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