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When to use moisture-resistant gyp-board or cement board

QUESTION

I’m writing with a question that I hope you can either answer or point me to the best resource that would be able to provide some insight.  

We’re doing architectural work for a national chain restaurant and I’d like to confirm that we’re using the appropriate backer board for tile walls. The question is: moisture-resistant gyp-board or cement board?

We use wall tile in food prep areas and restrooms. The walls get wiped down and might get splashed with water, but they don’t get hosed down or soaked.  

Let me know if there’s a simple rule when cement board should be used, as opposed to moisture-resistant gyp, or if there’s a reference standard that would shed some light on this question (I already tried the TCNA Handbook).

ANSWER

Thank you for contacting the National Tile Contractors Association. Industry-recognized wall tile installations are found in the TCNA Handbook

Two methods that use gypsum board are method W242 and W243. In the Environmental Exposure Classification section of each method it notes that they are appropriately used in Residential 1 or Commercial 1 type installations. Commercial 1 areas are described in the Environmental Exposure Classification of the TCNA Handbook as tile surfaces that will not be exposed to moisture except for cleaning and gives examples  such as: floors in areas with no direct access to the outdoors and no wet utility functions; hallways; dry area ceilings; soffits, decorative/accent walls; and corridor walls.

Commercial 2 is described as surfaces that are subject to moisture but do not get soaked or saturated due to system design or time exposure. Examples of Commercial 2 installations are: floors in bathrooms and locker rooms; some backsplashes and other walls such as bathroom walls and wainscot where water exposure is limited and or water is removed. Commercial 3 is described as areas that are soaked, saturated, or regularly and frequently subjected to moisture or liquids. It also lists some commercial kitchen walls.

Method W244 uses cement backer board in the installation and is suitable for Commercial 1,2, and 5 installation. 

Can we install over the sheetrock using a bonding primer or would it be better to install over a cement backer?

QUESTION

We are about to install 16” x 16” terrazzo cement tile (2cm) on a 10′ x 10 wall in a doctor’s office. The wall is a painted sheetrock. Can we install over the sheetrock using a bonding primer or would it be better to install over a cement backer?

ANSWER

The NTCA Reference Manual lists paint as a questionable substrate.

It may likely be better to install over a substrate that does not have paint beneath the bond coat where the bond of the paint to the substrate must be relied on to support the installation.

Some manufacturers have mortars or primer/mortar combinations that will bond to a variety of questionable substrates including paint. Consult your tile and primer manufacturer for their recommendation for adhering this particular tile to the substrate. 

Also be certain to check with the tile manufacturer to understand the required minimum deflection criteria for this type of tile. It will be at least L/360 or higher. 

– Mark Heinlein, NTCA Training Director

Backer boards – Health and safety knowledge is key to category

The introduction of increasingly rigid OSHA guidelines have lent even more credence to the popular trend of utilizing backerboards that promote both health and safety. Those working in the industry are concerned with protecting their health during installation, as well as protecting the end user against any exposure to contaminants later on.

Many professionals now choose state-of-the-art, cement-coated foam-core backerboards, which contain very low silica while providing a high-performance cement bonding surface. Professionals are also being warned to be aware of other substrates of concern, including formaldehydes and non-polymeric flame-retardants such as HBCD.


Backer Boards

1 Progress Profiles

The company’s Profoil Panel is an extruded polystyrene panel with a density of 48 kg/m3, provided on both sides with a waterproofing membrane. Panels are
36” x 60”/106” (91.5 x 152.4/270 cm) and available with several thicknesses. They are designed and tested to have mechanical resistance and long durability, allowing work to be carried out quickly and inexpensively. They are suitable for indoor application with a thermal insulation function on floor, wall and ceiling. Profoil Panels can also be used for partitions walls, tops for kitchens, shelves and different furniture. progressprofiles.com

2 wedi

The company’s original Building Panel is constructed of a high-density, closed cell extruded polystyrene core and reinforced with an ultrathin cement resin surface coating, resulting in a lightweight yet sturdy backerboard. Internally water- and mold-proof, it is part of the wedi Shower System. wedicorp.com