What Is a Nordic Wooden Spa? – Complete Guide | Storvatt

Nordic Wooden Spa: How It Works, Ideal Temperature, and How to Choose the Right One

Are you considering installing a wooden spa at home but aren’t sure where to start? Wood or electric heating? What temperature should you aim for? Above-ground or built-in? This guide answers all these questions in the logical order of a purchasing project—without unnecessary jargon.

How Does a Nordic Wooden Spa Work?

A Nordic wooden spa, also known as a Scandinavian spa or Nordic hot tub, is an outdoor bath designed for relaxation. It consists of a wooden tub filled with heated water, where you immerse yourself to enjoy a moment of relaxation in the open air.

The main difference between models lies in how the water is heated, with each system having its own specific features.

Wood-Fired Nordic Spa

This is the most traditional format. A stove is either immersed directly in the tub or positioned outside and connected via pipes, fueled by firewood. The water heats up through natural circulation (thermal convection) without an electric pump. This system, called a thermosiphon, requires no electrical connection: hot water rises, and cold water descends, creating automatic circulation.

However, you need to plan for heating time in advance—typically 1.5 to 3 hours, depending on the tub size, outdoor temperature, and wood quality.

Electric Nordic Spa

An electric heater (usually 3 kW) maintains the water at a constant temperature, coupled with a filtration pump and hydromassage jets. The spa is always ready to use, without any prior preparation. This is the most convenient option for daily or semi-daily use.

Hybrid Nordic Spa

Some models combine both systems: a wood-burning stove for the ritual and rapid heating, plus an electric heater to maintain warmth between uses. This is often the best compromise between authenticity and comfort.

How Does the Jet System Work?

In models with hydromassage, a pump circulates water through integrated nozzles in the tub. The jets are adjustable in power and direction, targeting specific areas of the body. Depending on the model, you’ll find 12 to 16 jets, interior LED lighting, and control via keypad or smartphone. Purely wood-fired models do not have jets, as relaxation comes from the warmth of the water rather than massage.

What Temperature Should a Wooden Spa Be?

This is one of the most frequently asked questions, and the answer is quite simple.

The ideal temperature for a wooden spa is between 37°C and 40°C. This range allows muscles to relax, improves blood circulation, and ensures you fully enjoy the immersion without risking overheating for a healthy adult.

Beyond 40°C, prolonged immersion becomes uncomfortable and is not recommended, especially for vulnerable individuals.

In electric or hybrid models, the temperature is automatically managed by a thermostat. In wood-burning stove models, you control it by adjusting the fire intensity and, if necessary, adding a little cold water.

How Long Does a Session Last?

Most users stay between 15 and 30 minutes per session. Beyond that, the heat can become overwhelming. If you practice hot/cold alternation, a session consists of cycles of 10 to 20 minutes in hot water, followed by 1 to 3 minutes in cold water or fresh air, repeated 2 to 3 times.

How to Choose an Outdoor WoodenSpa: 6 Key Criteria

1. Heating Method

This is the first decision to make. Ask yourself about your actual usage:

If you enjoy the ritual and spontaneity isn’t a priority, and you have space to store wood, the wood-burning stove is the most authentic option.

If you want the spa to be available at all times without preparation, the electric model is the way to go. Heating is automated, but you should factor in electricity costs in your operating budget.

If you want both, the hybrid model is often a relevant option, especially for families.

2. Size and Capacity

Wooden spas range from 2-person models (150 cm in diameter) to 10-person models (240 cm). For a family of 4 to 5 people, a 180 cm diameter is usually the right balance. For regular use among adults, a 150 cm model may suffice.

Beyond capacity, consider the total weight: a filled tub with users can weigh over a ton. You’ll need a stable surface (concrete slab or reinforced deck) to support it safely.

3. Installation Type

Three formats are available on the market:

• Above-ground spa: Placed directly on a deck or slab, this is the simplest and most flexible option. It requires no construction work and can be moved if you redesign your outdoor space. The wooden exterior cladding can be integrated or added.

• Built-in spa: Integrated flush with your deck or patio floor, this option offers a nearly invisible, elegant look that preserves the visual continuity of the space. The machinery is hidden beneath the floor.

• Semi-built-in spa: A compromise where the tub is partially recessed, with visible cladding above the floor. It requires less work than a fully built-in spa but offers more integration than a purely above-ground model.

4. Wood: Solid or Cladding?

This is a point often poorly explained in product descriptions. Two realities coexist under the term "wooden spa":

• A spa with wooden cladding has a tub made of acrylic or composite, with wooden slats on the exterior for aesthetics. This is the most common configuration in mass retail.

• A solid wood spa has a tub whose entire structure is made of wood, with thick staves (often 38 mm) in direct contact with the water. The wood provides thermal insulation, releases natural aromas, and forms the structure itself.

Durability, insulation, and sensory experience are significantly superior in the latter case. Among the most commonly used woods are Red Cedar (naturally rot-resistant and highly aromatic), larch (robust and European), and thermally treated wood (heat-treated without chemicals).

At Storvatt, we work exclusively with Clear 2 Red Cedar for our entire range of outdoor wooden spas, manufactured in the French Alps since 1997.

5. Origin and Manufacturing

The question of French or European manufacturing is increasingly relevant, and for good reason. It has practical implications: quality of the wood used, manufacturing control, availability of after-sales service, and lead times for spare parts.

A spa manufactured in France or in a country with a strong woodworking tradition (Scandinavian or Baltic countries) generally offers better long-term guarantees than an imported model with no traceability. Check the origin of the wood and the accessibility of customer service.

6. Equipment and Options

Beyond the basic model, several options can make a real difference:

• The insulated cover is essential: it limits heat loss between sessions and significantly reduces electricity consumption or wood requirements.

• The filtration system (cartridge or sand) determines how often you need to drain the water and its quality. With effective filtration, water can last 2 to 3 months before needing to be changed.

• LED lighting with color changes is often included in hydromassage models, enhancing evening comfort.

• Remote control via smartphone, available on some models, allows you to start heating before you arrive home.

Wooden Spa: What Budget Should You Plan For?

The price of a wooden spa varies significantly depending on the criteria mentioned above. Here’s a realistic range for the French market in 2025–2026:

These prices do not include installation. Plan for an additional budget for ground preparation, electrical connection (which must be done by a qualified electrician with a 30 mA differential circuit breaker), and delivery, which can vary depending on site accessibility.

The annual operating budget (maintenance products, filtration, energy) is generally between €200 and €500 for regular use in an electric model and significantly less for a wood-burning stove model.

Wooden Spa Maintenance: Practical Tips

Maintaining a well-designed wooden spa is less demanding than you might think.

Weekly: Check the water’s pH (ideally between 7.2 and 7.6), add bromine or chlorine tablets as needed, and rinse the filter cartridge.

Every 2 to 3 months: For regular private use, drain the tub, rinse the interior (a simple sponge wipe is sufficient for a solid wood tub), and refill.

For wood-burning stove models: Empty the ash drawer before each use and only use dry wood (moisture content below 20%) for rapid heating without excessive smoke.

Exterior wood (tub and cladding) requires no treatment for naturally rot-resistant woods like Red Cedar. It will gradually weather to a silvery-gray hue without losing its properties. If you wish to preserve the initial golden tone, a protective oil can be applied once or twice a year to the exterior only—never inside, to avoid blocking the wood’s natural interaction with water.

Frequently Asked Questions

Do you need a building permit?
Generally, no. A spa placed on a deck or on the ground does not require a building permit. Specific rules may apply if you build a shelter around it or depending on your local urban planning regulations.

Is a rigid wooden spa more durable than an inflatable model?
Yes, without comparison. An inflatable spa is a temporary piece of equipment with poor insulation and a lifespan of 3 to 5 years under the best conditions. A well-maintained rigid wooden spa can last several decades.

What’s the difference between a wooden spa and a Nordic bath?
A wooden spa with hydromassage is equipped with massage jets and electric filtration. The water is always available at temperature, without preparation. A traditional Nordic bath is heated by a wood fire, without jets, and the preparation ritual is part of the experience. Both can be made of solid Red Cedar and are used outdoors year-round. The choice depends on what you’re looking for: immediate comfort or a sensory experience.