Wooden Hot Tub Maintenance – How to stop leaks and swell the Wood

Wooden hot tubs are a nod to tradition and an authentic experience. Though they require a bit more attention compared to their fiberglass or polypropylene counterparts, proper care can prolong their longevity and enhance their performance.

The Art of Swelling a Wooden Hot Tub

Swelling is an essential process for new wooden hot tubs. This process allows the wood to absorb water, expand, and seal off small gaps in the tub’s structure. It’s important to note that a certain degree of leakage is natural and expected in wooden hot tubs, unlike in fiberglass or polypropylene tubs.

However, heat-treated (Thermo) wooden hot tubs are less permeable due to their manufacturing process, which closes the water capillaries in the wood.

The typical swelling time for a new wooden hot tub ranges from 2-5 days. During this period, bathing is not recommended. To assist in the swelling process, sawdust or coffee powder can be utilized. These materials, when added to the water, fill the gaps and minimize leakage.

Preserving Your Wooden Hot Tub with Oil

Impregnating the wood is a necessary step to mitigate the effects of moisture. This process, which involves applying oil, should be carried out at least twice yearly, but only on the tub’s exterior. Linseed oil is a common choice for this application. Over-drying the hot tub should be avoided as this could increase leakage.

Maintaining constant moisture levels in the wood is vital to prevent shrinkage and the subsequent leakage. During warmer months, it is recommended to always keep water in the hot tub. If the tub needs to be emptied for cleaning or repairs, it should not be left dry for long periods. However, ensure the hot tub is not overfilled, leaving about 10-15 cm from the top to avoid spilling.

Protecting Wood-Fired Hot Tubs in Winter

The guidelines above mostly apply to warmer months. In colder seasons, while it is possible to use hot tubs, it is advisable to drain the water after each use. The belief that small electric heaters linked to filtration systems can maintain water temperature during winter is misguided, and could potentially harm the tub.

When water freezes, it expands by approximately 5% in volume, which could lead to irreparable wood damage. Interestingly, the humidity levels in winter can keep the wood moist even in the absence of water. Nevertheless, it is essential to swell the hot tub after winter. Refer to our comprehensive guide on winter maintenance and storage for your fire-heated hot tub for more detailed information.