Tile/Stone Talk: Successful Steam Showers and Steam Rooms

Visual trowel lines, not 95% coverage and contact
Visual trowel lines, not 95% coverage and contact

By Greg Mowat, Forensic Tile Consultants

Steam showers and steam rooms are popular and common in exercise facilities, spas, hotels, resorts, and homes. Steam room and steam showers assemblies should be properly specified, detailed and installed by qualified tile contractors. They must be built correctly to contain all the emitted steam and moisture.

  1. For steam showers and steam rooms where the substrate is concrete or masonry, review detail SR613.
  2. For steam showers and steam rooms where the substrate is framed with wood or metal studs, review detail SR614-19, located in the 2019 Tile Council of North America Handbook for Ceramic Tile, Glass Tile and Stone Tile Installation.
  3. The assemblies SR613 and SR 614 are standard requirements for successful steam room and steam showers.

Contact your selected membrane manufacturer or mortar manufacturer for any assembly not conforming to SR613 or SR614 or for additional details and recommended installation materials.

Moisture, Condensation Concerns

Walls and ceilings should be adequately insulated to reduce condensation from forming in adjoining materials. Improperly installed tile and waterproofing assemblies in steam rooms or steam showers can result in tile falling off walls and ceilings, which can shut down steam rooms and steam showers.

Slippery tile specified causing plumbing official to close the steam room
Slippery tile specified causing plumbing official to close the steam room.

The presence of mold or bacteria growth can create detrimental health effects to users. The cost to repair improperly installed tile and waterproofing assemblies in these areas may cost two to three times more than the original installation cost.

The entire steam shower or steam room should be completely waterproofed within (underneath) the tile assembly and should be continuous for all tile assemblies – with excess moisture behind the tile routed to drains.

Waterproofing

The adjacent area outside the steam shower door is a wet area and should include waterproofing under the tile assembly, with both the waterproof membrane and tile sloped to the drain.

Wrong tile on bench seat
Wrong tile on bench seat.

Waterproofing in steam rooms and steam showers must adequately limit water or vapor transmission into adjacent spaces and building materials, according to the intended duration of use.

  1. All horizontal tile surfaces and underlying waterproof membranes in steam showers and steam rooms must slope towards drains.
  2. The waterproof membrane manufacturer may require using a vapor retarder membrane in addition to the installation of the waterproof membrane.
  3. Do not use polyethylene sheeting as a vapor retarder as condensation will occur on the warm/hot side of the polyethylene sheeting.
  4. For tile with direct bond to a waterproof membrane, the membrane must meet ANSI A118.10 minimum requirements and with a water vapor permeance rating of less than 0.5 perms.
  5. Follow waterproof membrane manufacturer’s direction for interface between the waterproof membrane and all drains.
  6. Follow waterproofing manufacturer’s directions for sealing all penetrations with recommended sealant and verify the fixtures in the steam room or steam shower are stainless steel to reduce corrosion of the fixtures.

Moreover:

  1. The shower pan membrane must slope a minimum ¼” per foot to weep holes in the drain or weep holes in the linear drain or overlap into linear drains. It must also wrap up onto the walls at least 3″ and at least 6″ above floors in showers without curbs.
  2. The waterproof membrane installed on the steam room or steam shower wall must overlap the shower pan membrane and make a watertight intersection.
  3. The minimum slope on ceilings is 2″ per foot toward perimeter walls(s) to reduce hot water dripping onto the occupants.
No weep holes on linear drain
No weep holes on linear drain.

Movement/expansion joints are mandatory at all changes in plane and where abutting all restricting surfaces. Slip joint type of movement joints are installed at wall to ceiling locations in steam rooms and steam showers.

  1. Maximum spacing of movement joints in the field of tile is 12’.
  2. See EJ171 Movement Joint Guidelines for Ceramic, Glass and Stone in the Handbook for Ceramic Tile, Glass Tile and Stone Tile Installation.
  3. Failure to accommodate the moisture and thermal expansion and contraction of the tile assembly has led to many tile ceilings falling into the steam room.

Ceramic tiles should meet the minimum requirements in ANSI A137.1 and recommended by the tile manufacturer for use in a steam room and steam shower.

Importantly, do not install glazed wall tiles on the floors or bench seats unless recommended in writing by the tile manufacturer. These tiles do not have adequate coefficient of friction (CoF) for a wet walking surface, or where occupants may sit or stand on the bench seat.

Installing Ceramic Tile

  1. Ceramic tiles and large format tiles are installed with LHT modified dry-set cement mortar meeting ANSI A118.15.
  2. Ceramic tiles are installed following ANSI A108.5 minimum requirements of 95% contact and coverage. Work toward achieving 100% contact and coverage to the substrate.
  3. After the tile is installed, the thin-set mortar setting bed shall be nominally between 3/32″ and ¼” in thickness to the substrate.
  4. Spot-setting with mortar and tiles is not an acceptable practice in steam rooms and steam showers as this process leaves voids underneath the tiles.
  5. Vapor drive condensation will occur in the void spaces between the spots of mortar due to temperature changes and will result in water, moisture collecting in the void spaces.

Installing Stone Tile/Slabs

Use caution when installing stone tiles and stone slabs in steam rooms and steam showers. Verify with the Natural Stone Institute and/or stone distributor or fabricator prior to using any recommended stone in a steam room or steam shower. Stone and stone tiles are not recommended in wet areas and may experience discoloration, de-bonding if the stone is with a mesh backing, or decomposition with expansion of minerals in the stone.

Stone slab was spot set leaving voids under the tile
Stone slab was spot set leaving voids under the tile.

Obtain a written recommendation in writing, or a waiver in writing prior to proceeding installation of stone tile or stone slabs in steam room or steam showers.

Backerboards

Do not install drywall or water-resistant green board as solid backing in steam showers or steam rooms as these products are subject to supporting mold growth (bio-organic growth). Again, verify with the backer board manufacturer if their product is recommended for this type of installation. If so, follow the installation instructions explicitly.

Backer boards should be installed with non-corrosive and non-oxidizing hot dipped fasteners at locations required by the backer board manufacturer. Mesh tape at the seams as required by the board’s manufacturer.

Conversions

Be cautious when asked to convert an existing shower, or a shower under construction, into a steam shower. The waterproofing in the walls and ceiling of the shower to be converted may be insufficient for a steam shower. Without adequate waterproofing, steam showers will fail to keep all water within the steam shower during usage.

Maintenance

Homeowners should be instructed to use neutral soaps when maintaining or cleaning their steam rooms and steam showers. Also, caution homeowners against using bleach or acid for normal maintenance in any steam room or steam shower. Likewise, be mindful that prefabricated steam showers are subject to slip, trip and fall conditions when soap residue occurs on the shower pan.

References/Specifications

Installation references include SR613 and SR 614 and EJ171 in the Handbook for Ceramic Tile, Glass Tile and Stone Tile Installation.

References in ANSI A108, A118 and A136 American National Standard Specifications for the

Installation of Ceramic Tile include:

  1. ANSI A108.01-3.6, ANSI A118.10 Shower pan membrane and waterproof membrane
  2. ANSI A108.1A, A108.1B, and A108.1C Mortar bed, reinforcing, and waterproofing
  3. ANSI A108.5 A137.1 for Installation of tile and for tile requirements
  4. ANSI A108.10, ANSI A118.6 for Installation of grout and for grout requirements
  5. ANSI A108.6, ANSI A118.3 for Installation of epoxy grout and for epoxy grout requirements
  6. ANSI A108.13 and ANSI A118.10 for Installation of waterproof membrane and slip joints and for waterproof membrane requirements
  7. ANSI A118.9 cement backer board with non-corrosive and non-oxidizing hot dipped fasteners

As a professional tile installer or contractor, if you do not have the references readily available, then ask for them and read them prior to performing the installation.

With all the available health benefits offered by steam rooms and steam showers, a long-lasting and successful tile installation is crucial.

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