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How to Assemble Our Indoor Modular Sauna Kit

Our Indoor Modular Sauna Kit Video Series

This article and multi-part video series applies to all indoor modular sauna kits

In this video series, we built a 4'x6' modular sauna with upper and lower benches. Modular refers to some degree that certain parts of the sauna can be reconfigured and disassembled for relocation elsewhere. Click here to view our outdoor prefab modular sauna kit sizes, and indoor prefab sauna kit sizes in the store. If we can be of more help, please email us or call us at 1.800.426.3929 or read on. Thanks!

3 Part Video Series | Complete Sauna Structure | Our Indoor Modular Sauna Kit

Video Shows: PART I: Placing Wall Panels on the Base Plate + the Ceiling Panels


For example, our 5'x7' prefab sauna measures 5'x7' INSIDE. The OUTSIDE (exterior measurement) is 8 inches larger: 5'8' x 7'8"

Thus, our 5'x7' sauna, is 8 square feet larger than our competitors — more room to relax and stretch your legs out!


Video Shows: PART II: Placing the Benches Inside the Sauna

NOTE: Our sauna benches have NO VISIBLE screws or nails. The leg supports show only vertical grain cedar on the proper side.

Jump below to view each segment of the Bench Assembly Videos.


Video Shows: PART III: Fastening Trim to the Sauna

NOTE: All trim pieces are labeled, but some are left slightly longer so you can cut them to exact length on site.

Jump below to view each segment of the Trim and Vent Videos.


Segments for All Parts are Shown Below in Detail

Setting the Sauna Base Plate | Sauna Tray Option

For this video, we used one of our wooden sauna trays as the base. Other options for an indoor sauna base are a cement slab or existing flooring.

IMPORTANT: The supporting sauna structure should be:

  • Home Floor
  • Cement Slab
  • Deck
  • Pressure Treated Lumber

We also offer a wooden sauna tray (optional). The tray is not a substitute for a strong structural base. Our saunas are never assembled directly on the wet earth.

Introduction: Assembling Our Indoor Modular Sauna Video Series

Set the Base Plate Squarely

Set the Base Plate Squarely

Our modular sauna packages sit on a base plate which acts as a slot interlocking with the bottom of our pre-made wall panels. The base should be leveled with shims. Note, to check if your base plate is perfectly square: Diagonals will measure exactly the same length.


Setting Your Sauna Wall Panels | Bottom and Top Plates Secure the Structure

NOTE: Our sauna packages are ALL 100% western red cedar. We use NO plywoods and NO glues what so ever; nothing but cedar!

Our base plate frame acts as a slot for the pre-made panel bottoms to slide into place

After leveling the base plate, we're ready to set our first wall panel in place in the slot. All wall panels come labeled. The sauna panels come together at the first corner and the top plate is added to steady the joint. The top plate fits into a slot along the top of the wall panels, similar to the bottom of the panel. The sauna structure takes shape as the first corner is secured. We point out that modular wall panels optionally include conduit ready for your electrician to run wiring for the heater, switches, lights, outlets, etc.


Start with a Side Wall Panel

Set Wall Panel Onto the Base Plate Slot

Securing the Corner Top Plate


Adjacent Sauna Wall Corner Assembly

Flush the Sauna Wall Panel to the Base

Front Wall Sauna Panels

Ceiling Panel and Conduits

Squaring the Ceiling Panel

Notes to Your Electrician


Noteworthy: Squaring and plumbing the sauna wall panels as you go is important step ensuring the last piece fits easily and properly. Slide panels snugly together to eliminate any gaps.

Panels are 6'4" tall x 4" deep, but their width varies as needed for your project. At a minimum a panel is 2 ft wide. We understand you may need your sauna walls easy to maneuver. So, we endeavor to make your sauna walls exactly how you'd prefer them. IF you'd like one piece walls, we are quite happy to oblige you.

Once together, open the top plate package. The top plate (or board) secures the top of the wall, so they do not tip over during assembly. Two screws are enough to assist, later you can return to tighten and add more screws as necessary. After completing one wall and the start of another, you can add another top plate. The top plate will assist you in assembling the sauna walls and prevent them from tipping. The top plate also slides into place securing the corners and side walls.

Sauna Benches and Supports | All Fasteners Are Hidden

After completing 3 sides of the sauna, we switch our attention to bench supports and benches

The lighting was best for showing you how the sauna benches fit without the forward wall in place. You may elect to do this too, as it's much easier to lay your benches down with an open wall rather than maneuvering them through the door. In most configurations having three walls up and fastened together is best.

Set Upper Sauna Bench Supports

Set Upper Sauna Bench Supports

Lay Sauna Benches in Place

Position the Lower Sauna Bench Supports


Place Lower Sauna Bench


Sauna bench supports are secured to the wall. These bench supports are built to accommodate upper and lower sauna benches for this customer's sauna size and design. By the way, we help design everything to your specs. Every sauna is customized to your needs at NO EXTRA COST. Review these videos for more tips when placing the sauna bench supports.

The sauna benches come precut and pre-built. In this video, we fasten the low bench to the wall. A couple of deck screws per bench leg is enough. The legs will sit flush with the edge of the bench face. The high benches can also be attached with screws, so no sliding occurs.

Typically, we put the ceiling panels before installing our sauna benches, but the lighting was much better to film bench installation with the ceiling off. After your benches are in, you can cover the sauna interior wall panel seams. We provide a duckboard flooring kit which comes a panel they will simply lay in the door.

Trim and Vents | Covering the Seams

With the wall and ceiling structure now fully set, we focus on some of the sauna kit's other decorative but useful aspects, trimming and vents.

Exterior Top Border Trim

Exterior Bottom Border Trim

Exterior Corner Trim

Sauna Exterior Door Trim

Sauna Slider Covers the Vents

Interior Sauna Ceiling Trim

Sauna Interior Corner Trim

Interior Sauna Floor Trim

Sauna Interior Trim For Seams


After setting your trim pieces in place, you'll notice they don't quite reach the top. This is intentional. Later, a facia board will cover the top rim transitioning into the celing panel.

When attaching your trim, use finish nails or brads. The deck screws are unneccessary, somewhat unsightly and can split wood. The 1x2 covers the seams. Go around the sauna attaching the corner trim pieces and covering the seams.

In many case, the sauna kits we build do not have a seam. We call our customers to see if they prefer a one piece wall and if you can handle it at your site. These saunas kits can built indoors or outdoors, so while no seams are great. It's not if you can't manuever the wall panels down stairs into a basement, etc.

Duckboard, Door Handle and Test! | Enjoy!

The sauna is complete, the sauna heater is on and our sauna expert drizzles water on the rocks. You should try this at home!

Sauna Duckboard Flooring

Sauna Door Handle & Setting the Self-closing Hinges

Sauna is Ready to Test!

Sauna is Ready to Test!


We call our cedar sauna flooring "duckboard", probably cause we tend to walk like a duck when our feet are wet. It comes pre-cut and ready to assemble. You can cover the walking area only or the entire area, as you prefer. We mount the cedar sauna door handle and describe how to wound the self-closing sauna door hinges.


Cedarbrook Sauna + Steam

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