The Hot Tub is generally made of redwood in the same manner as wooden wine casks. The constant soaking of the wood keeps the tub watertight. Other woods used are cedar, cypress, oak and teak. The hot tub for assessment purposes would be considered personal property and not assessed as real estate.

Spas are usually molded fiberglass with an inner acrylic or gelcoat finish. The gelcoat type of finish is susceptible to color fading and corrosion and will require resurfacing after approximately five years. Acrylic on the other hand is resistant to scratches and maintains its finish indefinitely. Spas of concrete and Gunite (air blown concrete on a webbing of steel reinforcing rods) are less common. Spas may be located indoors or outdoors.

The majority of the spas sold today are portable, but when determined by the assessor to be real property it should be valued in accordance with the table in the Maryland Assessment Manual. The cost table reflects the cost for the unit which includes the support equipment consisting of pump, filter, heater, air blower and necessary plumbing and hardware. This value must be indexed using the appropriate multiplier. In the instance of an indoor spa it would be treated as any fixture. Any spa outdoors would be subject to additional depreciation based on observed condition at time of physical review of the property.