The best part of owning an indoor spa is that you can always enjoy a relaxing soak no matter what the weather is doing outside. Plus, you can place your spa in a sunroom or solarium, helping to create the illusion of being outside. And depending on the type of installation you’re doing, you still have the option of having the spa sit on the floor or rest below grade.
However, don’t assume that an indoor spa is simply a hot tub in a room with four walls and a roof. Indoor spas present a litany of problems never encountered with an outside installation. The biggest challenge will be making sure there’s adequate heating and ventilation to prevent excessive humidity, which can cause structural damage to the home. A hot tub gives off a lot of steam, which can damage unprotected woodwork
Recessing Your Hot Tub into a Wooden Deck
A spa that is recessed into a wooden deck can be easier to enter and exit, and it doesn’t block backyard views like a spa that is placed atop a deck. When building this type of installation, you need to create a 4-inch (10 cm) steel-reinforced concrete pad to support the weight of the spa. You’ll also need to make sure that the spa equipment is accessible for repairs and maintenance.
A Expansive windows bring the outdoors into this hot tub solarium. Tile flooring is an ideal surface for any indoor spa installation.
and may produce dry rot, mildew, mold, and other problems.
Check with an architect and HVAC (heating, ventilation, and air-conditioning) specialist to ensure that the spa room has enough ventilation and is equipped to prevent moisture damage. Of course, every situation is different, and several factors contribute to how quickly water evaporates from an indoor spa:
• The relative humidity of the room
• The surface area of the water
• The temperature of the water
• The temperature of the air
• How long the cover stays off the spa
• How much splashing occurs from
bathers, jets, and water features
The larger the spa, the greater the evaporation. Evaporation also increases when the
water is warmer than the air and there’s lots of water being splashed out of the tub. Briefly stated, when water evaporates, it causes the water temperature to drop, the air temperature to increase, and the room’s humidity level to rise. The resulting warm, moist conditions are a veritable paradise for mold and mildew. If there’s any aspect of your spa installation that you’re trying to cut corners on in order to reduce costs, you don’t want it to be in the area of air quality. In fact, health research has shown that poorly ventilated indoor pool and spa environments can cause respiratory problems when aerosolized water particles carrying bacteria are allowed to enter the lungs. The medical term for this is hypersensitivity pn&hmonitis. Fortunately, this needn’t be a concern if you have adequate dehumidification and air exchange, and if you cover your spa whenever it’s not in use. For more information on preventing hypersensitivity pneumonitis with indoor spas, see page 52.