How to Replace Sauna Benches: A Step-by-Step Guide

How to Replace Sauna Benches: A Step-by-Step Guide

Sauna benches take more abuse than any other part of your sauna. They absorb sweat, handle the hottest temperatures, support your full body weight, and get sat on hundreds of times a year. Eventually, even the best wood shows its age - cracking, splintering, discoloration, or just feeling rough underfoot and under thigh.

The good news: replacing sauna benches is one of the most straightforward sauna maintenance projects. You don't need special skills, just decent measurements, the right wood, and a free afternoon.

When to Replace Your Sauna Benches

Not every sign of wear means replacement. Here's how to tell the difference:

Replace If:

• The wood is splintering and sanding doesn't fix it
• Boards are cracked through (not just surface checks)
• The wood feels spongy or soft when pressed - a sign of rot
• Dark staining from mold has penetrated deep into the grain
• The bench sags noticeably under weight
• The surface is so rough that it's uncomfortable even after sanding

Repair Instead If:

• Minor surface roughness - sand with 120-grit sandpaper
• Light discoloration - sand and the original color returns
• One or two loose boards - re-screw or replace just those boards
• Small surface cracks - these are cosmetic and normal in natural wood

Choosing the Right Bench Wood

Bench wood needs to be comfortable against bare skin, resistant to heat and moisture, and free of resins that bleed at high temperatures.

Avoid pressure-treated wood, plywood, or any composite materials. They off-gas toxic chemicals at sauna temperatures.

What You'll Need

• Replacement bench boards (see sizing below)
• Stainless steel screws (never use regular steel - it rusts and burns skin)
• Tape measure
• Circular saw or miter saw
• Drill/driver
• Sandpaper (80, 120, and 220 grit)
• Level
• Safety glasses

Step 1: Measure Your Existing Benches

Before ordering wood, measure everything:

• Board width and thickness. Most sauna bench boards are 1x4 (3/4" x 3.5") or 5/4x4 (1" x 3.5"). Thicker boards feel more substantial and last longer.
• Board length. Measure the full span of the bench from wall to wall or support to support.
• Number of boards. Count how many boards make up each bench tier.
• Gap spacing. Measure the gap between boards. Typically 1/4" to 1/2" for air circulation and drainage.
• Support frame. Check whether the support structure (stringers, brackets) is in good shape. If the frame is solid, you only need to replace the surface boards.

Step 2: Remove the Old Benches

1. Remove screws from the bench boards. If screws are rusted in, use a screw extractor or drill them out.
2. Lift boards off the support frame. They may be stuck from years of heat cycling - a pry bar helps.
3. Inspect the support frame underneath. Look for rot, loose connections, or sagging. Replace any damaged supports before installing new boards.
4. Clean the frame and wall area. Wipe down with a damp cloth to remove dust and debris.

Step 3: Cut and Prep New Boards

1. Cut boards to length. Measure twice, cut once. Leave about 1/8" clearance at each end for wood expansion.
2. Sand all surfaces and edges. Start with 80 grit to smooth rough spots, then 120 grit for an even surface, then 220 grit for a smooth finish.
3. Round over all edges. A router with a 1/8" or 1/4" roundover bit makes edges comfortable. If you don't have a router, heavy sanding on the edges works.
4. Pre-drill screw holes. Drilling pilot holes prevents splitting, especially near board ends.

Step 4: Install New Boards

1. Start from the front edge (the edge closest to where your legs hang). This board takes the most wear and is the most visible.
2. Use spacers between boards. A 1/4" to 1/2" gap between each board allows air circulation, water drainage, and room for wood movement.
3. Screw from underneath if possible. Countersunk stainless steel screws from below keep the bench surface completely smooth - no screw heads to sit on. If you must screw from the top, countersink deeply and consider wooden plugs over the screw heads.
4. Check for level as you go. Shim under supports if needed.
5. Leave a small gap (1/4") between the last board and the wall. This allows air to circulate behind the bench and prevents moisture trapping.

Step 5: Finishing Touches

• Do not apply any finish to the bench surface. No stain, no sealant, no oil. Sauna bench wood must remain completely natural. Finishes will off-gas at sauna temperatures and can burn skin on contact.
• Give the entire bench a final sanding with 220-grit after installation to smooth any rough spots from handling.
• Blow or wipe off all sawdust.
• Run the sauna at full temperature for 30-60 minutes before your first session. This "burns off" any residual wood dust and acclimates the new wood.

Maintaining Your New Benches

To maximize the life of your new benches:

• Sit on a towel. This is the single most effective way to protect bench wood from sweat absorption.
• Leave the sauna door cracked after each session for airflow and drying.
• Wipe up any standing water on benches after use.
• Sand lightly once a year with 220-grit to refresh the surface and remove any embedded grime.
• If mildew appears, scrub with a diluted oxygen bleach solution, rinse, and dry thoroughly.

Quality bench wood on well-maintained supports should last 10-15 years with regular use.

Need new bench material? Our saunas use FSC-certified heat-treated Canadian hemlock for benches - stable, comfortable, and built to last. Browse our outdoor sauna and indoor sauna collections. For overall sauna upkeep, check our sauna maintenance guide.