The right choice of timber and insulation will determine how long your sauna lasts and how enjoyable it feels.

Best timbers for sauna interiors

• Cedar: Aromatic, naturally resistant to moisture, and stays cool to the touch.

• Spruce: Traditional choice with a light colour and calming scent.

• Aspen: Pale, knot-free, and highly resistant to bacteria and fungi.

Avoid using treated timber inside the sauna, as chemicals can be released at high temperatures.

Here’s what you need to know before you start building.

Insulation essentials

Proper insulation ensures your sauna heats quickly, retains warmth, and prevents long-term damage. Use high-temperature insulation batts between studs, then finish with a silver foil vapour barrier to reflect heat and block moisture. Seal all seams with foil tape, leaving a 25–30mm air cavity between insulation and cladding for thermal break.

We bundle our sauna barrier paper with our heaters for good reason:

• Reflects radiant heat back into the sauna
• Acts as a vapour barrier, stopping steam damage
• Ensures faster heat-up times and better efficiency
• Prevents moisture damage to framing and plasterboard

Why timber choice matters

The wrong wood can warp, crack, or release sap when exposed to high heat, leading to costly repairs. Sauna-specific timbers like SAWO are kiln-dried, resin-free, and designed to handle the unique conditions of high-heat environments.

Expert insight from Warren: “Timber and insulation are the backbone of a sauna. Do them right the first time and your sauna will last decades. Get them wrong, and you’ll be fighting mould, heat loss, and repairs from day one.”

Timber choice impacts performance, safety, and lifespan. The best sauna woods are softwoods like Western Red Cedar, Aspen, and Spruce – especially from Arctic regions. They insulate heat well, handle rapid temperature changes, and stay cool to the touch for comfortable seating.

SAWO timber goes further: it’s kiln-dried, resin-free, sustainably sourced from slow-grown Nordic forests, and specifically rated for sauna use.

Cheaper timbers may warp, crack, or release sap under heat, leading to costly repairs and safety risks. Investing in sauna-grade timber ensures beauty, durability, and a safe experience.

Your Guide to Premium SAWO Wood Types

Choosing the right wood for your sauna is about more than just appearance, it affects durability, comfort, and the overall atmosphere. SAWO carefully selects only high-quality, knot-free materials to ensure a premium finish.

Here are the top options:

Western Red Cedar Panels

Western Red Cedar is highly valued for its natural resistance to decay and is one of the most recommended timbers for saunas and interiors.

• Naturally durable and long-lasting

• Distinctive aroma and warm appearance

• Free from knots or defects for a flawless finish

• Premium wood, with red cedar used in only 2% of saunas worldwide

Nordic Spruce Panels

Spruce is a classic sauna wood, known for its clean look and reliable performance under heat.

• Durable softwood with a uniform grain texture

• Withstands heat well, commonly used in traditional saunas

• Light colour offers a clean, spacious, and contemporary feel

• Grade A quality with natural stain resistance

Aspen Panels

Aspen is a smooth, white-toned wood that stays cool and comfortable in high temperatures.

• Excellent heat insulation and low flammability

• Remains comfortable to touch, even in intense heat

• Resistant to warping under sauna conditions

• Knot-free for a refined, modern appearance

Tip: When selecting wood for your sauna, consider both functionality and aesthetics. Cedar offers warmth and aroma, spruce provides a classic bright look, and aspen ensures comfort and sleek modernity.