Steam room requires careful planning
Question: I have wanted a steam room in my house for a long time. Are there certain things you must do to ensure a home steam room will work well? Can you tell me exactly how to build a steam room so that I don’t have any water or water-vapor issues? Will I need a special steam-room door, or will an ordinary shower door suffice?
Nate B., Lexington, Ky.
Answer: Your questions sure brought back a flood of memories from my childhood. When I was a kid, my friends and I would go swimming and play basketball at a traditional indoor health facility called the Friars Club. It had a steam room that was wonderful to sit in after swimming in the cool water of the pool. Although I have built a home steam room for more than one client, I have never indulged myself. My aching bones and muscles have complained about this oversight on more than one occasion.
As you get ready to build a steam room, don’t let the benefits of a steam room distract you. Construction details must be followed to make sure this room doesn’t become a haven for mold, mildew and wood rot. Steam and wood do not play well together. If possible, all wood framing for your new steam room should be treated lumber, including the subfloor.
Steam is simply water in the vapor form. This water vapor will readily return to the liquid state by condensing on cooler surfaces. Because the steam is so hot, the vapor will readily condense on surfaces that are warm to the touch. That’s what is happening when you get out of a hot shower and see a fogged mirror. Don’t think for a moment that the fog just picked the mirror; it’s on the walls, ceiling and even the wood cabinets in your bathroom.
To build a great steam room, you need to keep the water vapor within the steam room, where it can condense and run down to the floor drain. Any steam that does exit the steam room must be vacuumed out of the room and vented through the roof of your home. If at all possible, try to make sure the steam room is not located where one or more of its walls will be an exterior wall. If any of the steam water vapor escapes into the exterior wall, you will have serious water issues sooner or later.
I recommend you consider ceramic tile for the entire room, including the floor. You can use a membrane shower-pan liner that connects to the floor drain to capture all of the liquid water. This is the first thing that needs to be installed after the walls are framed.
The second most important element is a high-performance vapor barrier. You will need to get one that meets the ASTM E 1745 standard. This rigid standard will protect the wood in your home if you install one giant piece on the ceiling and walls without any seams. This vapor barrier must extend over the membrane shower liner that was lapped up onto the walls about 6 inches. The vapor barrier on the ceiling and walls will capture any water, returning it to the floor drain.
Before you start any of this, I urge you to research in great detail the steam-generation machine. The manufacturer of these heaters have very specific installation instructions that ensure the units will generate the amount of steam needed for the room. The steam room must be sized correctly for the steam unit you purchase.
The ceiling height in the steam room should not exceed 8 feet. It is a good idea to slope the ceiling so that condensation drops do not fall on you as you sit and enjoy the soothing steam. A slope of 2 inches per foot should suffice. Cover all surfaces in the steam room with ceramic tile or other similar product that is virtually waterproof. The tile must be applied to cement board or other substrate that is approved for use in a steam room. Use thinset mortar to apply the tile to the cement board.