A Guide for Selecting the Wood for A Hot Tub or Outdoor Sauna

Have you ever wondered how hot tubs differ from one another depending on wood type?

Many decisions must be made to choose the perfect wooden hot tub. Starting with model, size, color, wood and ending with accessories. If your decision is to have a completely natural product – a handmade wooden hot tub, you should consider which timber suits your expectations the best. There are five types of timber that are most common among our customers. Siberian spruce, larch, thermo wood, oak and red cedar. All of them are different in color and texture as well as in wood characteristics. Wooden hot tubs require more maintenance in general, but it depends on the wood type too. So which type of timber is the perfect choice for you? Find out below!

Siberian spruce

Wood for hot tub surround

There are 5 main wood types available and commonly used: spruce, larch, thermowood, oak and red cedar

are cedar hot tubs good

Red Cedar is the best thermal insulator among the commonly available softwood species and is far superior to brick, concrete, and steel. Properly finished and maintained, cedar will deliver decades of trouble-free service.

Siberian spruce hot tubs are the most popular selection. It is white, light, and soft, very versatile, easy to work with and maintain. Even though spruce has a very light color. Spruce timber can be stained virtually in any color you wish to suit your garden landscaping, which is not the case with Thermo wood or Larch. Spruce is one of the sturdiest types of wood, strong, stiff and tough. However, it is not naturally resistant to the rot thus it must be regularly treated and sealed, but with the correct maintenance, Siberian spruce is a perfect selection in most climates. It is highly recommended to treat the wood on the outside 1 or 2 times a year, by using linseed oil.

Spruce Pros And Cons


Larch wood belongs to the heaviest and most resilient conifer wood available on the market. It is valued for its tough, waterproof and durable qualities. Larch is a highly eco- and people-friendly and is considered a warm building material. Moreover, larch is much more resistant to insects and decay compared to spruce. The timber is resistant to rot when in contact with the ground and is suitable for indoor and outdoor building. Larch grows more slowly and therefore has a higher wood density, and contains a higher resin substance. Over time its resilience and density will only grow. It is very decorative and light. This wood has a much warmer brown color, with beautifully visible grain.

Larch Pros And Cons

Thermo wood

Thermo-processed wood is darker than natural wood, more weatherproof and more resistant to rot. Thermo wood is made through a chemical-free process using heat vapour and steam. The qualities are set at high temperatures (170 up to 230 °C) without the application of any excipients. Therefore, the process of killing the timber is environmentally friendly. The timber is much lighter than before and deformation through clamminess is reduced up to 90 %. The resin is removed from the wood during the thermal modification process. As a result, the wood does not secrete resin even in high temperatures. All of all thermo wood insulation qualities are better, it suffers from less moisture deformation and is more stable, perfect for use in outdoor conditions.

Thermo Wood Pros And Cons

Siberian Oak

Oakwood is exceedingly strong, heavy and durable. It is resistant to mould and fungal attack. Hard and heavy wood, with low stiffness and medium crushing. It also has extremely good steam bending properties. It is easy to machine, nail, glue, and screw. It stains easily and can take a wide variety of colors. However, due to the high capacity of water absorption, it tends to shrink or expand. Oak requires much more maintenance.

Oak Pros And Cons

Red cedar

Opposite to Oak, Red cedar hot tubs has very low shrinkage. Red Cedar is the best thermal insulator among the commonly available softwood species and is far superior to brick, concrete, and steel. Properly finished and maintained, cedar will deliver decades of trouble-free service. Because it is free of pitch and resin, Red Cedar has excellent glueing properties and with its high degree of dimensional stability, it perfectly accepts paints, stains, oils and other coatings, however, its rough texture may require extra work. Canadian Red Cedar is often regarded as the most sustainable building material available.

Red Cedar Pros And Cons

Maintenance of exterior wooden parts of the tub

We do recommend to perform oiling of exterior wooden parts twice per year. The most suitable time is prior and after the winter. It must be noted that only outside of a wooden hot tub should be covered with oil.  We recommend using linseed oil, however other solutions for wood maintenance are also acceptable. The normal lifespan is more than 10 years if the tub is well maintained.

2 Replies to “A Guide for Selecting the Wood for A Hot Tub or Outdoor Sauna”

  1. I live in the Virginia United States. I have been playing with the idea of building my own hot tub out of wood but Red Wood and Cedar is VERY expensive. Barrels are made from oak so my question is how often should I treat it if I go the oak route?

    1. Hi, thanks for the email. Well, non of the products (saunas or wooden hot tubs) is recommended to produce from oak. This type of wood will absorb much humidity, will expand, deform and in the end you won’t be happy, that is our experience.

      I would recommend spruce or thermowood.

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