Welcome to Steam and Refrigeration rooms.
As always, follow the Manufacturers recommendations for all the products you plan to use
steam rooms or refrigeration rooms. These projects need to comply with federal, state, and
local building codes.
Steam rooms and refrigeration rooms are similar, in construction, to shower room construction. They are similar, as they will generally include tiled walls, ceilings, and tiled floors. The floors, for example, will generally include a shower type drain.
They differ greatly from normal shower construction in several areas. The first difference is the requirement for a continuous waterproof membrane on all sides of the construction. They sometimes require that insulation be a part of the wall construction. They also require the addition of a sealed open slip joint at the point where the walls meet the ceiling.
Additionally in steam rooms, the ceiling should be sloped 2” per foot to keep hot water from dripping on the occupants. The slope can be directed to one wall or toward the center.
Let’s examine each of these additional requirements. The continuous waterproof membrane is required due to the water vapor transmission inherent to steam rooms. The steam can penetrate the tiled surfaces and flow into adjoining areas.
Insulation is required in stream rooms where a type of waterproofing is desired that will not withstand the heat generated. In refrigeration rooms the necessity for the insulation is obvious. Speaking of insulation, the tie wires and pencil rod is an additional feature not found in traditional shower construction.
The tie wire and pencil rod is the fastening device used to secure the metal lath or reinforcement since nails and staples cannot be used. The tie wires and pencil rod are used only when a scratch coat and mortar bed are used. When the tie wire and pencil rod system is used, the penetration of the membrane must be sealed satisfactorily to keep the membrane continuous and waterproof.
The sealed open slip joint refers to a detail that isolates the ceiling from the walls to compensate for excessive expansion and contraction from extremes in temperature.
Note that for mortar bed steam rooms, a sealed open slip joint is required in walls that exceed 16 feet in length.
In Figure A we see a cement mortar or thick bed installation. This project would start by applying the waterproof membrane over the framing members per the Manufacturers instructions for the desired membrane. The waterproof membrane is to be continuous throughout the installation and should be applied over a pre-sloped floor terminating into a two-piece type shower drain. The pre-slope of the floor, like the finished floor, should slope ¼ per foot to the drain.
If insulation is required for the membrane, the insulation should be applied over the membrane. The tie wires are then fastened through the insulation and membrane. The holes created by the fastening of the tie wires should then be sealed.
Next, ¼ pencil rod is attached vertically using the pencil rod. The 2.5 min. metal lath is then attached to the pencil rod using tie wires. The lath should be applied to the walls and ceiling cut at all corners and slip joints including any slip joints in wall areas exceeding 16 feet in length.
Caution should be exercised to not puncture the membrane during each step of the construction
process while the membrane is exposed.
The scratch coat of wall mortar is then applied to the walls and ceiling being sure to terminate the mortar at any required joints. Following the curing of the scratch coat, the brown or final coat of wall mortar covers the scratch coat on walls and ceiling. This final thickness of the wall and ceiling mortar should be ¾ to 1.
The floor mortar can be installed at this point and should be reinforced with 2” X 2” 16/16 wire or its equivalent. Be sure to keep the weep holes open at the drain with crushed tile or stone.
Tile can be installed with Portland cement paste on a mortar bed that is still workable or using dry set/latex Portland cement mortar on a cured bed. This is eventually followed by Portland cement grout.
Note: The slip joint should be constructed to allow rounded back-up filler made of compressible closed cell polyethylene or its equivalent that will not bond to the sealant used to cover it. The Manufacturers recommendations should be followed for the products and joint construction that are desired for use.
Figure B has been temporarily deleted as the drawing represented the thin bed steam room detail. Steam Rooms and Steam Showers can be constructed with cement backerboard. The installer must look on the backerboard layer as simply the replacement for the mortar bed in Figure A.
In constructing this system, there will be no need for the tie wires and pencil rod seen in Figure A. Corrosion resistant screws will replace the tie wires and pencil rod. A waterproof membrane continuously applied behind the insulation is still required. The reason for the waterproof membrane is to prevent steam vapor from reaching outside un-involved areas that can be damaged from the presence of accumulated moisture. The most popular insulation consists of 1 inch rigid insulation.
Since the insulation, membrane, and backerboard layer will mean at least a 1-1/2” thickness, longer corrosion resistant fasteners will be necessary. For wood stud construction, the fasteners will need to penetrate the studs at least ¾ inches. Since the normal coated backerboard fasteners are only manufactured in 1-5/8 inch length, a stainless deck screw in 2-1/2 inches should be used. For steel studs, the fastener need only self tap into the stud and hold the layers securely to the framing.
The question will arise concerning the penetrations of the membrane through the system. The threads and head should be coated during application in an effort to reduce the amount of water vapor penetration into the system.
Many manufacturers’ recommend the application of a topically applied membrane over the backer board layer that is continuous throughout the Steam Room including the floor (to drain), walls, and ceiling. I personally agree with this recommendation as the topical membrane further restricts water from entering the system through the tile grout joints. The topical membrane should never be used as the primary waterproofing in Steam Rooms and Steam Showers.
In Figure C, we see a refrigeration room. This is a mortar bed or thick bed installation very similar to the mortar bed steam room. The framing members and concrete substrate are behind the insulation and are not shown in the drawing.
The key differences here are that the insulation is an integral part of the design.
Frost proof tile must be selected for this project.
Also note that the reinforced concrete floor must be installed over the insulation. For floors subject to forklifts, a 4” thick slab should be used.
(The Tile Doctor)