Hot Tub Supply Spa Depot
Wood Hot Tubs
What you need to know.
 SpaCyclopedia Index   History of the Hot Tub  Find the Best Portable Spa  Hot Tub Prices

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player


Round wood hot tubs enjoyed popularity in the 1970s, but had largely disappeared by the late eighties. Although a handful are still made to this day, modern self-contained portable spas have for the most part replaced them in the evolution of hot water bathing.

We're often asked to explain the difference between a hot tub and a spa. Spas, typically rectangular in shape, are larger and made of acrylic or a similar durable, lower maintenance material, with advanced water features, jetting, and purification systems. It's really a matter of semantics: all spas are hot tubs, but wooden hot tubs are not normally referred to as spas.

  Old wood hot tub

Construction of Wooden Tubs

Wood hot tubs, often made of redwood or cedar, are assembled from many vertical boards called staves .The edges of the staves, which look like a standard 2 x 4, are angled so that when the staves are assembled edge to edge, the result is a round vessel. The bottom of each stave is carved with a groove called the croze which fits to the width of the floorboards.

wooden hot tub construction The flooring is constructed of horizontal planks. One edge of each floorboard has two or more holes drilled in it and the other edge has corresponding pegs. The pegs make assembly easier by keeping the floorboards properly aligned. The ends of each floorboard are curved slightly, with the center floorboard being the longest and with each of the succeeding floorboards on either side being slightly shorter. The final result is a round, flat floor surface.

The entire structure is held together in the same manner as round wooden barrels. The staves are strapped in place by several round metal bands, tightened with nuts.

Our forests Wooden tubs use a lot of lumber to manufacture. As the noble forests of North America have dwindled over the years, supplies of quality redwood and cedar have fallen, and the suitable grades of wood for hot tubs has been on a steep decline. This has forced prices up, as the quality of available lumber has gone down.


Seating Considerations
A major disadvantage of wood hot tubs is lack of comfortable seating. Lounge and bucket seats obviously cannot be molded into wood as they can in an acrylic spa.

Standing upright in the water, or sitting on wood plank benches are the main seating options in these tubs.


Jets & Hydromassage
Just soaking in hot water can have therapeutic benefits, but the vigorous jet action of modern contemporary spas, which mix air and water for stimulating hydro-massage of the entire body, is at least half of the experience. By comparison, the water circulation of wood hot tubs might seem primitive to you, although jets can be added.

external plumbing Since wooden tubs do hot have a protective, insulated cabinet like portable spas, any jet plumbing and water circulation pipes must be mounted on the outside of the barrel. Aside from the lack of aesthetic appeal, external pipes can freeze and break in cold weather.  Since the tubing cannot be properly insulated, a huge amount of energy is lost as well.


Prepare for Higher Maintenance
Like wooden boats, wood hot tubs can be esthetically pleasing. The other factor that they have in common with wood boats is high maintenance.  Unlike acrylic spas, wood tubs require a break-in period. Wood tubs leak when first put into service, and during break-in time must be allowed for the wood to absorb water, swell, and seal the cracks between the staves.

maintenance of vessel Two of the common woods used in hot tubs are redwood and cedar. These woods contain naturally-occurring toxins which to a limited extent help prevent the wood from rotting. These compounds leach out into the water, especially in a new wood hot tub.

Bathing is not recommended until the tub has been drained and refilled with fresh water, perhaps several times during the break-in period.

< Well broken-in wooden tub

Owners of wood hot tubs should be prepared for a lot more periodic maintenance than acrylic spas require. We believe this is the primary reason that their popularity dwindled so dramatically after modern spas were introduced.

Leaks are the Norm
Wood hot tubs are much more prone to leaks than spas, in part because there are so many more places for water to leak from. The planks must never be allowed to dry out (and shrink) from low water level, or leaking problems will definitely develop.

Leaky wooden tub Freezing weather can cause moisture in the wood's cell structure to expand, microscopically breaking the fibers apart, eventually resulting in cracks as shown here. Exposure of one side of the hot tub to direct sunlight in the hot summer sun, while the other side is shaded and cooler, can sometimes cause warping, which is another cause of leaks.
Termites & Carpenter Ant Infestation wood-devouring carpenter ants

Over time, even durable woods like heart redwood will rot and disintegrate as a result of both microorganisms and vermin.  A wood hot tub is an appetizing target for carpenter ants which are attracted by the moisture, and termites too, especially if there is ground contact. These pests can devour the structure.

  wood plank damage

Sanitation Issues
Wood is a naturally porous material, and
microorganisms love to hide and multiply in the microscopic nooks and crannies.  Unfortunately the conventional disinfectants, bromine and chlorine, not only oxidize bacteria, they also break down the wood itself. For this reason, most local health codes prohibit wood hot tubs for public or commercial use. The risk of disease being spread to the public is considered too great because bacteria held in the wood can easily be transmitted to others.

Alternative sanitizer system If you already own a wooden hot tub or are getting one, consider a friendlier alternative sanitizer such as Cleanwater Blue sanitizer. It's an EPA registered copper ion based bactericide & algicide-- a technology which does not rely on harsh bromine or chlorine to purify the water.

Wood Decomposition Problems
The effects of chlorine and bromine can strip lignin out of wood. Lignin is a pulpy white cellulose substance which binds the organic structure of wood together. Over time, the tub will look as if to be growing a milky fur on its interior surfaces which can clog filters and cause a lot of other messy sanitation problems.

maintenance The only solution to this recurring maintenance issue is to drain the tub, allow the wood to dry out, and then sand all of the interior surfaces by hand using coarse, then finer sandpaper until it has been removed down to hard, sound wood. Then the tub must be refilled, allowing time for the water to re-swell the dry wood to reduce leaking.

Algae Contamination in Porous Wood
Algae blooms can also be a serious problem in wooden hot tubs. The common method to deal with this issue is to superchlorinate the water and hand brush all of the affected interior wood surfaces with a stiff brush. This forces the chlorine below the surface where the algae is rooted.  The process often has to be repeated several times, completely draining the water each time, until the algae is eradicated and the tub disinfected. Proper
sanitizing is essential.

Energy Consumption

Heat Loss

Although wood itself has some insulating properties, it loses most of its R-value when it becomes saturated with water. Because heat retention is such a major shortfall, a properly fitted insulated cover is essential and will help to mitigate some of the expense of this wasted energy.

Overall, wood hot tubs use a lot more energy to maintain their temperature than today's super-insulated, low-maintenance portable spas such as our quality Belize spa line (pictured right).

  Energy-saving spas

Beautifully durable LifeCast Spas are now more affordable than ever before!


Spa Depot, The, Spas & Hot Tubs - Dealers, Olympia, WA

BizRate Customer Certified (GOLD) Site - The Spa Depot Reviews at Bizrate
BizRate Circle of 
Excellence Site – The Spa Depot Reviews at Bizrate