FAQ - General Practices

These practices may be utilized with many wedi products and are not only recommended for the installation of a specific product. Please relate to specific product installation manuals to compare whether the following best practices may help you with your specific installation situation.

wedi foam products can be dented when pressure is applied, will this cause problems after the ceramic tile is adhered over these dents?

No, once the cells in the foam are compressed they will not re-inflate. When thinset mortar is spread over these indentations the voids are filled and will set as such. When dents are wide and deep, you may want to consider filling with thinset mortar and cover the area with wedi Subliner Dry waterproofing sheet membrane. This is not done to protect the integrity of your waterproof foam underlayment but it will help to have the surface under the tile in such area dry as fast as the surrounding area. This way, no darker, wet looking areas will occur which will need longer to dry out.
As long as the wedi XPS foam is not punctured all the way through the foam, the waterproof qualities of the closed cell matrix foam will remain. In situations where this is unavoidable (such as at the attachment points where fasteners are used) wedi Joint Sealant must be applied over such fastener points.

How do I make tile repairs on wedi building panel and shower base installations?

When removing tile from wedi building panel installations, please cut grout and tile carefully before you utilize a strong putty knife to take off tile and mortar chips. Please be careful when cutting, that you don’t cut all the way through the wedi panel as it would compromise your waterproofing ( a minimum of ¼” should be left intact). Please refrain from using hammers or other tools that expose the building panel assembly to vibration and impact pressure. This could cause seam sealing and reinforcement to open up and would put your waterproofed application at risk. In the event, that you tear out a full piece of wedi building panel from your wall assembly, please cut out the whole panel in the area and size of your tile. Use a utility knife with an extended blade so you are able to cut this piece out with 45 Degree mitered edges. Cut a replacement wedi panel piece with mirrored 45 Degree mitered edges and insert the piece into your cut out in the wall after a bead of wedi joint sealant has been applied all around the contact seams for this replacement panel. Carefully seal over the (typically) 4 seams with more wedi joint sealant and spread flat with a putty knife. Before applying the sealant, you might want to tape surrounding tile as not to get any sealant onto the good tile. Let the wedi joint sealant cure for 30 minutes. Now back butter a new tile and press it firmly on the repaired wedi building panel, keying the thinset in with a downward push first and move the tile up while pressing the tile firmly into position. Re-grout the area.

Do wedi foam products offer sound deadening qualities?

The wedi Building Panel is not engineered to be used as a sound deadening underlayment. Nor is the wedi shower base reducing impact sound. They will lower airborne sound but, due to firm and full surface contact bond to substrate and tile, they will not reduce impact sound. However, many tileable sound reduction floor membranes can be installed below wedi shower bases and offer a great way to install a sound proofing. This may add value, especially when installing in high-rise buildings or on upper floors.

Are any of wedi’s foam based products “green“ products?

Conventionally, “green products” are fully organic and sustainable. wedi foam based products are therefore not “green”. However, the process of manufacturing is engineered to not harm our environment. Extrusion agents used are CFC free and the product obtained a “Global Warming Potential “ rating as per UN charts of 1 . Global-warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. A GWP is calculated over a specific time interval, commonly 20, 100 or 500 years. GWP is expressed as a factor of carbon dioxide (whose GWP is standardized to 1). For example, the 20 year GWP of methane is 72, which means that if the same mass of methane and carbon dioxide were introduced into the atmosphere, that methane will trap 72 times more heat than the carbon dioxide over the next 20 years. The substances subject to restrictions under the Kyoto protocol either are rapidly increasing their concentrations in Earth's atmosphere or have a large GWP. In addition , wedi also does not contain flame retardants such as HBCD but uses polymeric fire retardants which stay bonded to the material. wedi foam based products also protect organic structural parts of buildings such as wooden parts against rotting, replacement and mold, thereby actively prolonging the lifetime of an installation, resulting in a savings of resources and energy. In addition, wedi foam based products add insulation and can eliminate heat leaks of building envelopes insulation or may dramatically improve the performance of floor heating systems when installed underneath such systems, and help conserving energy. wedi building panel can also be used actively on facades to add to the efficiency of older insulated walls or standard batts insulation. Especially also in areas often subject to insufficient insulation and heat loss such as window or door frame areas.

Are the wedi foam products toxic?

No, the foam is inert and inorganic. It will not produce carcinogens when handled or cut. It is produced utilizing a CFC-free blowing agent. All wedi foam products have a certified global warming impact of 1 (no negative impact).
wedi foam products are also manufactured in compliance with the Stockholm Convention and REACH program, both prohibiting the use of HBCD or HBCDD flame retardants. The UN subsequently outlawed their use. In the US, the EPA added these flame retardants to the list of potentially dangerous materials. Foams such as XPS are commonly treated with HBCD or HBCD in countries like China. These products may still be imported into the US, while Canada put in place a schedule to prohibit import and trade by 2018. These flame retardants are dangerous and carcinogenic as they do not chemically bond to the foam and may outgas.

Why are wedi shower base installations less expensive than traditional shower pan liner-mortar bed construction?

If done properly, the traditional method includes a pre slope, shower pan liner and mortar bed, which easily takes 8 man hours to install, compared to approximately 30 minutes for the wedi Fundo Shower Base. Depending upon the mortar bed thickness, 2-3 days drying time is often required before installing ceramic tile. The wedi Fundo Shower Base is tile ready immediately after installation.

Which ceramic tile sizes can be used with the wedi Fundo Shower Base?

2" x 2" or larger sizes can be installed with modified thinset mortar and cementitious grout. All ceramic tiles less than 2" square should be grouted with an epoxy joint filler compound. All ceramic tiles less than 1"x1” square or less should be grouted with an epoxy joint filler compound and set in epoxy based thinset. Tiles or tile formations and patterns which include larger and smaller tile are treated according to the recommendation for the smallest tile in the formation and it is always the shortest side of a tile that is used to determine the setting and grouting material under the above stated rules. For tiles larger than 2” x 2" square there is no limitation as to the setting or grouting material. Only organic, premixed tile adhesives (“Mastic”) must not be used in any wet area over wedi product. It is a particular benefit of wedi shower bases that they accommodate for the placement of large format tile. These are cut along the wedi base’s slope lines along which slope fields meet. For commercial applications or where wheelchair use is expected, please contact wedi Technical Service for the appropriate tile formats and setting material recommendations.

Why is the wedi Fundo Shower Base so much safer than a conventional concrete shower pan?

The only way to safely install a conventional concrete shower pan is to apply waterproofing on top of the pan (though liquid membranes on concrete bases often crack and can easily be penetrated by traffic inflicted forces or other (if only accidental) contact with sharp or heavy objects). However, more often topical waterproofing is not applied and instead, a pre-slope is typically installed underneath the shower pan bed and pan liner, which allows water to run towards the weep hole drain. This process is unpredictable and water may simply remain sitting in the porous concrete bed due to clogged weep holes and cause mold growth. Mortar bed shower pans often fail since the pan liner is sandwiched between the layers of concrete which can result in tears that cannot be seen or easily repaired (tears often occur especially where the pan liner is tightly installed over the curb and applied in a multi-corner fashion). Another concern is the watertight installation of the pan liner toward the drain flange. Since the pan liner is nailed directly to the studs, leaks can occur where the fasteners penetrate it. Larger pan liner assemblies have to be siliconed together, same as for corner pieces. These seams are subjects to constant water pressure and may tear apart during floor movement or simply when mortar beds initially dry out upon installation and therefore shrink. The wedi Fundo Shower Base does not absorb any water like concrete and completely protects any substrates from water exposure.

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