The Watsu Center

The Watsu Center

Owner: Mr. Harold Dull, Director

Location: Middletown, California USA
Date: 1992 to 1996, will be completed this year.
Cost: $4,500,000


On a majestic hillside overlooking the forested ravine and mountains of northern California sits a most unusual building. It is a special school of massage that is performed in water. Harold Dull, the inventor of this system, has built a school which features five 81/2 meter to 10 meter diameter spheres formed in wood and sheathed in stucco cement and waterproof vinyl composite. A waterfall seemingly connects two outdoor pools, with a cave behind it. The spheres contain classrooms, commercial kitchen, and offices, sleeping quarters, residential quarters and a three-story studio. Fireproofing is created by a series of outdoor sprinklers at the center roof of each sphere. In case of fire the spheres are immediately immersed in water becoming impenetrable to fire. At the base of each sphere is a water trough of moving cold water that naturally cools the air around the sphere. Small tubular openings contain solar-powered fans that draw the water-cooled air in and push hot air out the roof top openings; creating a natural, continuous air exchange system. Recycled paper pulp mixed with water-based glue is sprayed into the open structural cavities of the walls to provide excellent insulation. The spherical shape--minimizing surface area while maximizing volume covered and structural strength--has proven itself to maintain a cool interior temperature even when the outside temperature reaches beyond 42 degrees Celsius and even without the insulation put in. The spherical shapes also activate wind flow to further cool the buildings. They are also extremely durable and stable; easily able to resist earthquake forces acting upon them. In fact, it has been proven that the sphere is the strongest most efficient shape in the universe. Every detail of the building is unique including the stone retaining walls in which the rocks seem to grow straight out of the wall with brilliant glass marbles placed between the stones. The floors too are made of silver quartzite flagstone with flattened glass marbles of iridescent and transparent quality shimmering in the floors. This is a one-of-a-kind building open to public tours and visited by millions of persons from around the world.

Construction Materials: Native boulders and stone, Madrone, Birch, Douglas Fir and Redwood(dome structures), glass, Polygal, spray-on cellulose, spray-on concrete, acrylic waterproofing, galvanized steel pipe, waterproof nylon and ceramic tile.

Special Features: Five 3/4 spheres with two spacious levels in each; spheres are extremely strong and efficient--excellent for use in this earthquake and landslide area. All five spheres can be built in two weeks time and be ready for assembly prior to issuance of the building permit; the building faces predominantly north--away from the sun for insulative purposes in this very hot climate; solar-powered ceiling fans in every sphere create a continuous circulation of fresh air that is drawn in over a series of water-cooled troughs at ground floor level; Spray-on cellulose is used as both inner wall insulation and interior wall finishing providing very good acoustic insulation as well; opening windows provide natural, economical cross-ventilation for temperature control; all stair areas are simultaneously used for equipment storage; vegetation is used to control solar gain adapting to summer and winter climatic changes; an exterior sprinkler system over every sphere can be manually activated in case of fire or extreme heat rendering the building virtually fireproof; passive solar glass tubes provide hot water throughout the building; on-site boulders and rocks are used as barriers to keep large animals away.



General Background: Mr. Harold Dull is the inventor of a new form of therapeutic massage called, Watsu. It is administered in a pool or large body of water and utilizes stretching and shiatsu techniques in a weightless, aquatic environment. A pool of water is essential to the therapy. In the summer of 1991 one of our intern architects was learning the techniques of Watsu from Mr. Dull when, during the course of casual conversation, Mr. Dull mentioned that he had a vision of a school for Watsu that should be like no other building in the world. The intern suggested Mr. Dull contact us to discuss various ideas and possibilities.

When Harold Dull came for his visit he was visibly delighted with what he saw in our office and we talked further about the kinds of uses he envisioned. The nature of the site was crucial to understanding the limitations of the design. After spending three days at the site making note of the soil qualities, the sun movement, the climatic and panoramic qualities, the challenges of the project began to become clear.

Earthquakes and soil slides loomed as destructive occurrences. The heat, normally around 90 to 100 degrees eight months a year was another challenge. The south-facing slope of the site overlooks a beautiful, tree-lined valley with green mountains rising beyond. Fire ever threatens the site and being uphill the air currents would potentially fan the flames of any burning object.

Taking these many hazards into account the building required structural qualities and features that effectively addressed these hazards. Thus, the character of the building must be based upon a structural system that was rigid enough to disperse earthquake shaking yet be economical in its use of materials and subsequent enclosure of space. Geodesics came into view here as they are inherently strong, lightweight, economical--using 1/3 less materials to cover the same amount of volume as a box of equal size. Because the dome shape also minimizes the amount of surface area it means less heat build-up from the intense sun. The shape also lets water fall evenly around itself creating a cooling feature consistent with its form. Geodesics also provides an aerodynamic efficiency suited to this hillside site.


The final constructed design was developed in response to Mr. Harold Dull's desire to give each functional area more privacy instead of being grouped together. To achieve this meant creating a series of structures in close proximity to each other. Again, geodesics seemed to be an intelligent choice for a structural system. Taking into account economy and structural strength we decided to use the geodesic sphere as a basis for enclosed volume. The framing struts of the spheres could be cut before the construction permits were issued saving even more time. The five 3/4 spheres can be framed and sheathed in two weeks. The bottom half of the sphere is attached to a concrete ring apron, which makes the structure itself work as an integrated unit dispersing omnidirectional stress and strain forces. An added benefit are the aerodynamic characteristics of the sphere. It is an excellent form for wind creating relatively little turbulence on its surface.

Inside insulation is provided by a honeycomb, prefabricated paneling system called Hexcel, . This paneling is cut into triangular shapes suited to the unit cells of the geodesic spheres and clipped into place. The R-values are in excess of R-24 and the panels are inflammable and do not lose strength when immersed in water and dried. They are also termite-proof. The panels provide a one-step construction process of structure, sheathing, insulation and interior wall membrane thereby eliminating three time consuming and costly steps in construction.

Interior finish is provided by a spray-on cellulose material called, Thermo-con, which is recycled paper mulch mixed with water-based glue. The material is non-toxic, slightly soft to the touch and can be sculpted by using the spray gun to build up chosen areas. One inch thickness provides approximately R-6 insulation values and it is extremely sound absorbing. Its density can be controlled upon application and a wide selection of color is available. For our uses a white color was chosen to reflect heat and to create the ambiance of expansive space.

At ground level, vertical pipe supports are placed at various angles creating a sense of dynamic movement. These columns are integral with the built-in furniture and wall systems of the spheres. Each of the five spheres are surrounded by a continuous trough of water. Above these troughs are a series of hollow tubes which draw-in fresh air that is cooled by passing over the water troughs. Once inside the air warms up and rises passing through a series of open vents at the periphery of the second floor. The warmed air continues to rise following the curving walls of the sphere until it reaches the peak of the sphere and exits through the upper vent cap opening. A solar powered fan blows air down to create a continuous flow cool and warmed air to keep the interiors cool when temperatures outside soar to beyond 90 degrees Fahrenheit. Opening windows, located mostly on the north sides for cooler air, provide cross-ventilation--a natural air conditioning system.

The design of the Watsu center also features two pool areas, one indoor and one outdoor, both connected by a waterfall. The enclosed pool is surrounded by a glass canopy with metal "spikes" pointing skyward. These spikes contain directional lighting to light the immediate grounds of the school. Heat gain from the sun is controlled by the use of planted potato vines and Bougainvillea which grow dense and lush in the summer and thin-out during the winter.

The pools are four feet deep and are warmed by passive solar tubes which face south. The water is recycled through a filtering system in the underground mechanical room. A continuous ramp leads from the pool deck level into the water and concludes at pool floor level. The pools are easily accessed by the physically impaired. Of note is how the elongated pool soars out over the hillside creating a compelling visual experience from its deck area.

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