For centuries wood has been used in the making of barrels. These barrels or tubs are watertight and are often used for ageing alcohol. Wood that is properly treated and cured can be watertight in the inside whilst leaving the outside porous enough to breathe. Wooden hot tubs are becoming more popular because they leave a low carbon footprint and they are arguably more attractive than acrylic hot tubs.
The best quality wooden hot tubs are built from hard wood taken from the heart of the tree, known as the heart wood. The wood must be properly cured and treated to prevent it from warping or cracking and to protect it from the weather. Wooden hot tubs can made from a variety of woods including cedar, cypress, teak, oak, mahogany, spruce and pine.
The tub is typically constructed of wooden side slats or staves with a wooden base. The staves are attached to the floor and then to each other so that they form circle. The watertight seal is made naturally by the expansion of the wood as it swells.
Contrary to popular belief, wooden hot tubs are easier to look after and keep clean than acrylic spas. Recent evidence has shown that wooden surfaces harbour fewer bacteria and that wood is naturally self cleansing (of course you still need the correct chemical balance in the water). The most important point is to ensure air can circulate around the hot tub base and that it is not placed directly onto soil. A cedar wood hot tub will largely look after itself, silvering over the years. However, if you want to keep the natural colour of the wood, you can oil the outside with cedar oil.