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.

Are fasteners required for securing the wedi Building Panel to a block wall?

It is not generally approved or endorsed. However, you may tile right over and  overlap onto seat top edges and similar exposed foam edges of wedi construction if the tile is also bonded with at least 50% or more of its surface to a wedi cement surface.

What is the building panel made of?

The wedi Building Panel is made up of three components: foam, mesh, and mortar. The blue foam is extruded polystyrene. It is inherently waterproof as it provides a closed cell matrix. This is due to the process under which the foam is created. The foam is extruded under enormous pressure, creating a dense mass of tiny, closed cells so tightly packed together that water cannot penetrate the insulation, nor can the insulating air escape from the cells. The single foam cells share the surrounding cell foam walls with the neighbor cells so that no room is left open in between the single cells in the matrix. It offers no capillary activity. The foam is then covered with a glass mesh to add strength and rigidity, which in turn is coated with a modified cement resin coating.

What is the wedi building panel?

The wedi Building Panel is a waterproof tile underlayment for walls and floors, manufactured by wedi GmbH in Emsdetten, Germany, as well as in the USA , in wedi’s factory in Batavia, Illinois. It consists of an extruded, polystyrene core and is covered in a fiberglass mesh and modified cement resin coating. The blue foam core is closed cell, extruded polystyrene that does not allow the transfer of water and retards water vapor transmission but is not a vapor barrier. The alkali resistant glass mesh adds strength and rigidity to the building panels. The cement coating allows for adhesion as a bonding surface to any standard or modified tile adhesive on cement or epoxy basis. The panel is engineered to be used in interior applications for the installation of ceramic tile, stone or glass tile and various other finishes from stucco to laminates: on walls, floors, countertops and many more applications where traditional backer boards are used. The wedi Building Panel is available in 2' x 4', 3'x5' , 2'x8', 3’x8’, 4’x8’ sheets in various thicknesses 1/8", 1/4", 1/2", 5/8", 3/4”, 1", 1 1/4”, 1 1/2" and 2"

Who produces it?

It is manufactured in by wedi GmbH in Emsdetten, Germany, as well as in the USA , in wedi’s factory in Batavia, Illinois.

Why is the wedi Building Panel waterproof as opposed to “water resistant” backer boards?

The wedi Building Panel is 100% waterproof because of the material it is made of. The foam that wedi Building Panels consist of is extruded foam; this means that the foam is created through a process of infusing a styrene resin with a blowing agent. It is a single piece of foam with air pockets within. This results in a foam matrix that is honeycomb in nature. The extrusion process creates foam that is closed cell; it lacks voids through which water could migrate. It has zero capillarity and cannot wick water.
For example, the foam used to make a standard white coffee cup is highly compressed expanded Styrofoam. However, this compressed foam will allow for liquid to move around the units of which it is made.
With this EPS foam, little balls of foam are compressed tightly together to hinder the passage of liquid through the independent pieces of foam. This is why a liquid stain can often be found beneath a Styrofoam cup sitting on a cold granite countertop after it has allowed vapor transfer created by hot coffee or tea. Commonly, EPS foam may absorb water up to 15% of its volume. EPS density will make this foam’s rigidity higher, but it will not make it waterproof. Other foams, including Polyurethanes, are rarely used for waterproofing either. Their cell structure is often inconsistent offering varying degrees of water absorption.

What sizes are available?

The wedi Building Panel is available in 2'x4', 3'x5', 2'x8', 3’x8’, 4’x8’ sheets in various thicknesses 1/8", 1/4", 1/2", 5/8", 3/4”, 1", 1 1/4”, 1 1/2" and 2".

How much do the wedi building panels weigh?

The wedi Building Panels vary in weight depending upon the thickness of the board. In the 3 x 5 ft. size 1/4" is 8.07 lb, 1/2" is 8.67 lb, 5/8" is 8.97 lb and the 1" is 11.4 lb.

Does the wedi building panel have an R-Value?

Yes. The R-value varies depending upon building panel thickness at a rate of 4.3 per one (1) inch.

Does the wedi building panel have a fire rating?

The wedi Building Panel will not provide a fire barrier. It will not add anything to a fire or fuel a fire, as the cells of the foam will collapse due to extreme temperatures above 175°F. It passed the Steiner Tunnel Test/ ASTM E84 with a flame spread of <20. Where a one-hour firewall is required, the wedi building panel should be applied over a surface that can provide such a rating (such as certain drywall systems).

Can wedi building panel be used on floors?

Minimum 1/8” thick wedi Building Panel functions as an excellent substrate for most flooring applications. wedi Building Panel  ¼” over standard EGP plywood structure 16” o.c.,  and installed with 3x4” tile using standard cement based setting materials, has been rated for heavy-duty commercial use by the Tile Council of North America (TCNA) using the industry standard known as the Robinson Floor Test (ASTM C627). It can be applied over a wooden or concrete subfloor. When applied over plywood, the recommended joist spacing is 16" on center, 23/32" or greater plywood with no deflection in the subfloor greater than L/360 as outlined by the TCNA, following local building codes or the IRC.
L / 360 equates to the length of the span between floor joists then divided by 360. If applied over a cement subfloor the slab should be fully cured and free of debris. A full cure is not necessarily reached after 28 days as is often, and falsely, claimed. Only CM / core probe measuring may reliably determine the status of a concrete slabs curing process. The board will function as a crack bridging membrane because cracks in the cement subfloor will not likely transfer through the foam as easily as through other inelastic tile backer boards.

On the floor should I leave room for expansion joints between wedi Building Panels?

No, the wedi Building Panel is inert and will not shrink or expand over time. All wedi Building Panels should be butted together and laid staggered. An expansion joint around the perimeter of the floor should be considered, leaving a gap of 1/8" to the surrounding walls to better resist structural movement. Consider the use of expansion joints in your tile assembly over wedi products according to Recommendations found in the Tile Council of North America’s Handbook for Ceramic Tile Installation. Our building panels should not be installed over expansion joints in concrete slab construction.

Should I stagger my joints?

Yes, the wedi Building Panels should be staggered to minimize the length of the surfacing of potential breaks/ cracks in the substrate.

Can the wedi Building Panel be installed on walls?

The wedi Building Panel can be applied directly to wood or metal studs, over primed gypsum board (green board or drywall), masonry walls and existing ceramic tile. The recommended thickness for a stud wall application is 1/2", 5/8", 3/4”, 1”, 1 1/4”, 1 1/2” or 2”. Thinner panels may be installed over solid surface substrates. The particular thickness is dependent solely upon the desired effect that the contractor wants to achieve. If a contractor is applying wedi Building Panels over a gypsum product, the 1/2" board will most likely be used as this will allow for the trim pieces of ceramic tile to cap where the wedi Building Panels end.

Can I install the wedi Building Panel directly to the studs?

Yes, minimum 1/2" thick wedi Building Panels can be fastened directly to wood or metal studs with only a few fasteners per sheet {one (1) wedi Fastener per one (1) ft. of stud}. When the board is applied directly to studs the 5/8" material can be used if the ceramic tile to be applied will have a flush or surface finish with tiled 5/8” drywall in adjacent, dry areas. The 1" board can be applied directly to studs if a "floated" look is desired or over 19” o.c. framework. The framework itself must be designed as a loadbearing, suitable substrate. All vertical wedi Building Panel ends at framework corners must be fully supported by framing.

How do I install wedi building panel over framing which is not plumb, or not straight or not squared or show any combination of these issues?

As with any other backer board and tile underlayment, you will need to create a surface that is loadbearing, true and flat, as well as plumb and squared from floor to ceiling.

Unfortunately , many 2x4 wood framing studs are not in a perfect  condition or framed perfectly fine.

It is important to deal with the deficiencies of framing prior to installing wedi panel or any other tile backer board. If you choose not to, these deficiencies will either show later, when the corrections are done in the tile surface layer or the backer boards cannot be installed tightly fitted below the tile.

Here are safe and good ways to ensure proper framing before installation of wedi building panel:

  1. Use wood furring strips nailed to studs, either along entire studs or parts of studs
  2. Sister studs, replace studs, add cross blocking

Here are methods NOT to use, without limitation:

  1. Wet or Dry shimming with sealants, caulks, or other types of adhesives (cement thinset mortars or other types including general construction adhesives)

wedi Building panel must be mechanically affixed to framing which provides the properties needed to safely support the building panels. Only wedi fastener systems are used.

Can I install the wedi Building Panel over green board/drywall?

Because the wedi Building Panel is 100% waterproof, it is not necessary to use green board/drywall behind the installation. However, it is common for this material to be applied in wet areas and it has no detrimental effects on the installation if waterproofed with the wedi Building Panel. Before installing wedi Building Panel over any gypsum containing product, a primer must be applied prior to application of thinset mortar which is used to attach the wedi to such drywall assembly. Fasteners may be set in some areas to temporarily attach the two boards and compress the thinset adhesive. Do not forget to seal such fastener points with wedi joint sealant.

Can I use the wedi Building Panel in an exterior application?

The wedi Building Panel is not recommended for use in a horizontal exterior application. On a vertical surface, the wedi Building Panel can be used in certain instances. Please contact wedi Technical Service when planning this type of installation.

Can I install wedi Building Panel in a steam shower or steam room?

Yes, wedi is the preferred choice of backer board worldwide for more than 30 years when it comes to steam rooms. wedi panels are not only waterproof but also function as a vapor retarder. However, wedi does not support the current industry standards as per the TCNAS, nor does wedi support the suitability of the Test method applied (ASTM E96 E). Even products that meet the industry standard for continuously used steam rooms of .5 PERM are not proven by any substantial research to be effective retarders in all steam room – and shower installation situations. In addition, wedi realizes that only an entire interior vapor retarding concept and installation will be effective. In other words, all protrusions, seams, fastener points must be designed and installed to retard water vapor successfully. This is why wedi favors over and in addition to its closed cell foam products (a) extra safe strength vapor retarders and (b) full surface vapor retarders installed on the entire interior wedi surface prior to tiling.   

wedi therefore recommends the application of the wedi epoxy based vapor barrier (= effective retarder) or wedi Subliner Dry (= effective retarder)  over its closed cell and cement resin coated foam product in steam room/shower applications. Using thicker wedi panels than the common ½” wall/ceiling backer boards over framing will offer some added value: increase of insulation value which will dramatically add to the energy efficiency of steam generators which are operated by temperature feelers. As well as that intersections and transitions to sloped ceiling panels can be installed in a safer (interlocking) method.

Adding wedi’s vapor barriers will ensure decades of safe functionality of a steam room application- no matter whether commercial or residential steam room/shower. wedi diligently works in technical committees of NTCA and TCNA to change the industry standards to increase the required strength of a vapor retarder and/or barrier in steam room installations. wedi building panels also provide a thermal insulation value , minimizing the water vapor pressure differential to the outside area behind the wall and ceiling substrate and adds to energy efficiency through insulating the warmth in steam rooms. Please see wedi’s full guidelines for residential and commercial steam rooms on this website in the technical data sheet “wedi Building Panel”.

Can I install wedi Building Panel in a Dry Heat Sauna?

No, wedi Building Panels should not be installed in areas subject to temperatures above 175*F. The foam could deform in such installations and applied tile could heat up to a point, where users could get hurt.

Can I install wedi Building Panel in and around Fireplace applications?

This would depend on how close the wedi building panel will be located to the heat. wedi Building Panels should not be installed in areas subject to temperatures above 175*F.

Can I install wedi Building Panel in a swimming pool?

No. With the assumption of perfectly installed seams in a wedi Building Panel assembly, wedi could be used in pools. wedi Building panels are 100% waterproof. Due to high water pressure in large pools and the inevitable high number of seams and other protrusions ( lights/fixtures), we do not recommend the use of wedi products in swimming pools or other pools. wedi offers premade customized pools and pool modules- made in the wedi factory in a controlled environment and using computer aided design and manufacturing robot technology for precision work results needed in such challenging applications.

Can I install wedi building Panels in conventional concrete or pan liner shower floor installations?

Yes, unlike with cement based backer boards, you can actually install the wedi building panels all the way down to the pan liner, before you float a concrete base against them. The result is a square, plumb installation ready for tile. wedi building panels, unlike cement backer boards, do not wick water.

Can I use the wedi Building Panel in an exterior application?

The wedi Building Panel is not recommended for use in a horizontal exterior application. Too much movement potential, especially over wooden deck or patio construction, and the many application specific, complicated details to be considered (flashings etc.) are frequently challenging the tile installing trades. wedi therefore does not warrant or support tiled decks or patios in which wedi is a part of the assembly. Please contact wedi Technical Service when planning this type of installation on a vertical surface, the wedi Building Panel can be used in certain instances such as facades. Please consult wedi for proper installation in different climate zones of North America. On facades, please integrate wedi building panel into the building envelope considering that wedi Building Panel functions as an insulator and also vapor retarder. Its proper positioning in an exterior wall assembly is therefore depending on the climate zone in which the installation is done.

How is the wedi Building Panel cut?

The wedi Building Panel is cut with a utility knife, scoring is unnecessary as the blade will be able to penetrate through the board. Mechanical saws and handsaws can also be used.

The wedi Building Panel 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 broken they will not re-inflate. When thinset mortar is spread over these indentations the voids are filled and will set as such. As long as the wedi Building Panel is not punctured all the way through the foam, the waterproof qualities of the board will remain. In situations where this is unavoidable (such as at the attachment points where screws are used) wedi Joint Sealant must be applied.

Is the wedi Building Panel strong enough for my ceramic tile installation?

The wedi Building Panel has been rated for heavy-duty commercial use by the Tile Council of North America (TCNA). This means that wedi Building Panels can serve as an underlayment on floors in a residential application such as kitchen or living room floors, in bathrooms or stairways, as well as spaces such as office buildings, breweries or anywhere that there is heavy duty use. When installed on walls, wedi Building Panels can support any standard ceramic tile or natural stone (up to 23 pounds / sqft). On ceilings, it can bear up to 18 pounds/sqft. The board will not fail under normal conditions, including moderate impact, such as the weight of an adult person or the blow of a wayward refrigerator.

What is the correct method to join 2” or thicker wedi Building Panels together when building a wall using more than one of the building panels?

When building such extended wet area walls using 2” thick or thicker wedi Building Panels, such panels can be joined by a Z notch connection or tongue and groove connection (using 2” wide  ¼” or 1/2” wedi panel to connect two panels showing a 1” deep grooves created with a router). Both connections require wedi Joint Sealant to adhere both panels at all contact areas.

When screwing the ½” board to a furring strip attached to a block wall, the wedi screws may protrude too far, poking the block wall, and pulling the furring strip off of the wall. What is the best way to address the situation, assuming that it is not possible to fur the wall out further to accommodate the size of the wedi screw?

...possible to fur the wall out further to accommodate the size of the wedi screw?

Choice of hardware (fasteners and anchors) depends on the furring strip depth and the wall type behind the furring strips. The length of wedi Fasteners is kept as short as possible under max desired load considerations but wedi should be contacted for fastener recommendations. It is also an option, particularly with thinner furring strips such as 1” strips, to switch to fasteners and appropriate anchors with a view on fastening into the solid wall, disregarding the furring strip. All fastener options should work with wedi Washers. For a safe installation, based on the individual situation, options should be recommended and approved by wedi.

Can the wedi Building Panel be attached to a flat block wall using Thinset adhesive only, and without using any fasteners? If so, what is the correct notched trowel to use for this application?

Typically, a ¼” square – to ¼” x 3/8” trowel can be used over flat and even walls, using the appropriate Thinset and without need to use fasteners. However, temporary fasteners might come in handy to keep the building panel safely attached while the Thinset cures. Please ensure the Thinset adhesive is not used to true or level substrates. The compressed thickness of the Thinset adhesive should never exceed the permissible maximum thickness recommended by the Thinset adhesive manufacturer. 

Can I increase the build out on a wall, for example by using a ¼” wedi Building Panel to be installed on top of a ½” wedi Building Panel. The ½” panel would be installed to a substrate such as a framed wall. Can I use Thinset adhesive between both panels to laminate them together?

... panels to laminate them together?

You can install the ½” wedi Building Panel with wedi Fasteners, with all seams sealed (fastener head should be sealed also). Your ½” wedi Building Panel remains the ultimate waterproofing barrier over the substrate, especially when installed within a Fundo system. Then use, for example the ¼” wedi Building Panel and apply in a full surface Thinset bed using a ¼”x¼” trowel. Stagger this panel’s seams so you don’t align with seams in the ½” panel assembly. The seams of the ¼” panel should be topically waterproofed by applying a ½” bead over all seams and spreading it flat over the seam using a putty knife. Essentially, you are adding weight to the assembly in form of extra wedi panel and Thinset. However, it won’t be enough weight to become a risk considering our panels and fasteners load capabilities.

What is the correct procedure for finishing the wedi Building Panel with a plastered/painted finish?

Only cured cement stucco or cement based patching coats will adhere to wedi in wet areas. As such, these coats should be applied prior to painting and hide wedi’s mesh and grid structure, providing a smooth and even surface. Wet area or exterior grade designated paint can then be applied in areas above the shower head and beyond tiled areas. Any plaster type materials, for use over wedi products but safely outside a wet area, require special cement surface primers (masonry primers) before any other coats or gypsum plaster materials are applied. All types of plaster shall have a minimum thickness of ¼” for strength.

Are fasteners required for securing the wedi Building Panel to a block wall?

That really depends on the wall’s condition (eveness/flatness, adhesion friendliness). There may be special thinset adhesives available to adhere without the use of fasteners. Wall anchors are mostly used with leveling mortar dabs used between wedi Panel and a block wall (like spot bonding). This can be done with wedi Panels 5/8” and thicker only.

What is the wedi Fundo Shower Base?

The wedi Fundo Shower Base is a prefabricated, tile ready base that is installed on a wooden or concrete subfloor using latex or polymer modified thinset mortar (1/2" thick before compression). It does not require a shower pan liner underneath, and no further waterproofing on top. It is already pre-sloped and includes a drain system with no weep holes necessary. It is made of extruded polystyrene foam and is 100% waterproof, and is coated with a cement based resin coating and fiberglass mesh.

Which wedi Fundo Primo Shower Base sizes are available?

The wedi Fundo Shower Base comes in 3'x3', 3'x4', 3'x5', 3’x6’ (center drain), 3'x6' (offset drain), 4'x4', 4'x5', 4'x6', 4'x7', 5'x5', 5'x6'; 5’x6’ offset drain, 6’x6 ‘and 5'x7' sizes . These are the standard sizes which are equipped with a 4”x4” stainless steel drain cover or optional cover designs upon request.

Can I cut the wedi Fundo Shower Base to size?

Yes, using a circular or table saw, the wedi Fundo Shower Base can be cut to size. The drain is centered so in order to maintain a proper slope layout, the base should be cut equally on at least two sides. The 1/2"x1/2" channel along the pan's perimeter always needs to be remade so that the 1/2" wedi Building Panels will fit properly. Please note that, if cuts are made, the shower base will lose height due to the sloped product being cut away. A good recommendation is to not cut more than 6” off any wedi shower base type so that variations in height are no more than 1/8” (as bases are sloped at a rate of ¼” / 1 ft.). Some Riolito Neo bases may not be cut at all in the area of the channel drain.

Can I extend the wedi Fundo Shower Base?

Yes, using wedi Fundo pre-sloped Extension Panels. These panels always need to be connected to the wedi Fundo Shower Pan using a shiplap notch which is prefabricated into the extension panels. When panels are cut, the shiplap connection has to me remade into the panel. wedi Joint Sealant must be applied inside the shiplap joint and an additional bead is applied on top of the joints (use a putty knife to smooth the sealant over the joints). Some of wedi’s shower bases have, due to application or size, a different perimeter thickness. Accordingly, please choose the appropriate extension panel type (e.g. Extension Panel Ligno with Ligno shower Base). Or add height under extension panels so they can connect with their Z -notch channels at the top edge of a thicker shower base. Height can be increased by adding and thinsetting the needed thickness of wedi panels or other backer underlayments under the extension pane or the floor. Please note, wedi extension panels feature a true one way slope . When connected to most bases their one-way slope will transfer to a 4 way slope. This should be considered at the time you decide about your floor tile layout. wedi extensions can be joined at their sides to extend shower bases on multiple sides. This too, is done by fabricating mirror fitting Z-Notch channel connections and using wedi joint sealant when joining two extensions.

Do local building codes allow the wedi Fundo Shower Base system to be used instead of a conventional shower pan liner and mortar bed construction?

Yes, your inspection department will recognize: the wedi Fundo Shower KIT / system is, throughout, rated as waterproof as per ANSI 118.10 (tested using ASTM D4068; 48 hrs standing water exposure) and is certified by ICC via PMG Report 1189 stating compliance with all national codes : IRC, IBC, IAPMO PS106, IAPMO PS46, IPC, National Plumbing Code of Canada (and more codes)

How much time does it take to install the wedi Fundo Shower Base?

A standard size installation, for instance 3'x5', takes approximately 30 minutes to install. The wedi Fundo Shower Base is tile ready after being installed on a wooden or concrete subfloor.

wedi Fundo Shower Bases are installed in thinset mortar suitable for a substrate. Can I use wedi Joint Sealant instead?

No, please use a full surface setting bed of thinset mortar when installing. This will ensure, that no floor imperfections or voids under the base could possibly produce vibrations (transferring into tile and leading to cracks) or hollow space sounds (annoying to owners). Sufficient coverage, support and adhesion are especially important in the areas at the drain or under sealed transitions such as from base to wall panels.

Can I use the wedi Fundo Shower Base with any other tile backer board other than the wedi Building Panel?

We do not recommend it and here is why: The wedi Fundo Shower Base is part of a complete system offering a complete warranty. With traditional backer boards, Building codes require a vapor retarder behind the boards to connect into a pan liner or to a hot mop to protect the shower floor/wall including the curb. Such a waterproofing method installed “behind” or “under” the tile substrate must be applied throughout floor, wall and sometimes ceiling because the waterproofing products/layer have to connect to contain water. A pan liner under a wedi shower base, however, is not feasible. Therefore, a vapor barrier behind another backer board (example cement board) cannot be connected to the floor waterproofing. Although a pan liner is not needed underneath the wedi Fundo Shower Pan, waterproofing is necessary in order to meet the 4"-6" wall requirement that the traditional shower floor liners are subjected to in traditional code books. This is, in the wedi system, done by using the waterproof wedi Building Panel with all seams being sealed with wedi Joint Sealant in between the board joints and the channel connection of the wedi Fundo Shower Pan, Building Panels and Curb. One option to use another board is, however, that this board would receive a topical waterproofing (instead of a vapor barrier/poly sheet behind) such as a sheet membrane or liquid membrane. Such membrane would have to be sealed and overlap onto all wedi shower floor components enough to create a secure connection. The warranty for such installation falls to the manufacturer of the product that failed.

Can I use the wedi Fundo Shower Base with floated wall installations instead of wedi building panel?

We do not recommend it and here is why: The wedi Fundo Shower Pan is part of a complete system offering a complete warranty. With traditional floated walls, Building codes require a vapor retarder behind the lath to connect into a pan liner or to a hot mop to protect the shower floor/wall including the curb. Such a waterproofing method installed “behind” or “under” the tile substrate must be applied throughout floor, wall and sometimes ceiling because the waterproofing products/layer have to connect to contain water. A pan liner under a wedi shower base, however, is not feasible. Therefore, a vapor barrier behind another wall surface (floated wall) cannot be connected to the floor waterproofing. Although a pan liner is not needed underneath the wedi Fundo Shower Pan, waterproofing is necessary in order to meet the 4"- 6" wall requirement that the traditional shower floor liners are subjected to in traditional code books. This is, in the wedi system, done by using the waterproof wedi Building Panel with all seams being sealed with wedi Joint Sealant in between the board joints and the channel connection of the wedi Fundo Shower Pan, Building Panels and Curb. One option to use a floated wall is, however, that this wall would receive a topical waterproofing (instead of a vapor barrier/poly sheet behind) such as a sheet membrane or liquid membrane. Such membrane would have to be sealed and overlap onto all wedi shower floor components enough to create a secure connection. The warranty for such installation falls to the manufacturer of the product that failed.

How do I instruct the plumber to setup the drain system before installing the wedi Fundo Shower Base and its drain assembly?

For the models Primo and Ligno, a 2" Schedule 40 ABS, PVC, Cast Iron or Copper Pipe (per ASTM standards) needs to be installed where the drain is located. The 2" pipe is cut flush to the surface of the subfloor or a maximum of 1/8” above the subfloor surface. In the case of Fundo Ligno, the pipe is cut 5/8” below the subfloor surface. For models Riolito Neo, only ABS pipe may be connected unless a multipurpose solvent cement / glue is used that would also allow for the drains ABS material to connect to PVC pipe. A pipe connecting to a Fundo Riolito Neo has to be cut 1 1/4” below the subfloor surface. In all cases it is important the P-trap is securely mounted underneath the subfloor so that the pipe and trap can carry water without moving. A hole 5" in diameter must then be cut around the 2" pipe to allow for installation of the wedi Fundo Shower Base Primo-drain assembly. Ligno requires a 6 1/2” hole to recess its drain. Riolito requires a tight oval cut out that fits the drain trap provided by the system (template provided). The plumber could also install a 2" pipe after the wedi installation if access is available from below. If a Cast Iron or Copper drain is existing, please contact wedi for a fitting sealing gasket or transitional connectors which we will provide or which we can recommend for you to purchase at select plumbing wholesale sources.

What is the thickness of the wedi Fundo Shower Base?

For Primo bases, the height at the exterior edge is between 1 1/2" and 2”, depending on size of the system. For Riolito, the height varies between 1 1/4” to 2 3/4” depending mostly on design style of the base. For Ligno, the height is 3/4”.

Do I need to use the black plastic riser pieces in wedi Fundo’s Drain Parts Box?

In the case of Fundo Primo and Ligno, a square, black riser is added to offer the option of using it under the stainless steel frame and cover if and as needed. It can be cut to height. It does not have to be used at all. In the case of Riolito Neo, several black risers are added to support the linear drain cover. They may be increased for additional height or they can be cut to a lower height. These risers or supports have to be used with this system.

Do I have to glue or screw drain covers, its risers or supports, or and their frames to the wedi shower base?

No, please just insert. Otherwise, a dam against water flow could build up and the shower needs longer to dry out. With Fundo Riolito Neo it is especially important to not glue in the covers or their risers. The linear cover has to remain easily removable for cleaning purposes.

What‘s the best way to determine the Fundo Shower Base size I need?

The best way to determine a shower base size is to measure from the floor drain center to the beginning of the (framed) wall. In addition, determine the position of the wedi curb as it will be placed on the floor. Draw a line where the wedi curb would touch the base on the bottom (not where the curbs Z-notch interlocks into the channel. This line on the floor can be viewed as another wall for measuring purposes. Now you know for all sides of the shower base the length from the floor drain center (equals shower base (drain) center) to the outside edge of the base’s sides (wall).

How do I set small tiles on a wedi base?

When setting tiles on a Fundo Primo or Riolito shower base that are equal or smaller than 1“square, use an epoxy thinset as these tiles sometimes rock over trowel lines, and use epoxy grout to better connect the small tiles at their edges. Tiles smaller than 2” x 2” square, but larger than 1” x 1” square may be set in modified thinset (ANSI 118.4 class) but must be grouted with epoxy. Pebble Stones may be set in epoxy or modified thinset and should be grouted with a sanded cementitious grout. Over Fundo Ligno, tiles smaller than 2” x 2” square or pebble stone must not be used.
Over all wedi Fundo shower bases , tile sizes larger than 2” x 2” are not limited and all large format tile may be used, provided that grout lines are fabricated where wedi bases show their slope lines between different and adjacent slope fields.
Please note, many tile formats or patterns mix smaller and larger tiles. In addition , many types of tile have no square format or sizes and feature longer and shorter sides. Always use the shortest side of a tile, or the smallest tile in the assembly to determine the proper choice of setting materials including grout.
When installing river rock or pebble stones, skim coat the pan using modified thinset or epoxy thinset, then begin setting your stone, and use grout recommended for this application by the grout manufacturer. *When installing river rock mounted on mesh, be sure the thinset below the river rock bonds fully to the rock. In some cases you may want to remove the mesh. Ensuring maximum adhesion when using any mesh mounted tile is a challenge. When in doubt, remove the mesh.

How do I layout for large format tile use on a wedi Shower Base?

The best way to set large format tiles is to mark lines from each corner to the center of the drain location. There are exceptions such as Fundo Primo 36x72 offset or Riolito Shower bases. Here, instead of running lines from corners to drain centers, you would run from corners to the corners of the rectangular trench. Be mindful of the fact that some Riolito bases feature true one way or two way slopes that are easily laid out for. However, these models show smaller flat areas to be considered you will be creating an X. Simply dry fit your tiles, and start in the base. Once you‘ve obtained your desired look, simply install your tile using modified thinset. Be sure to use the TCNA guidelines for grout spacing based on your tile size and allowance. Be sure to install an expansion joint between the pan and bathroom floor tiles as there is a change of plane. Also install an expansion joint at base to wall transitions and all other change in planes (corners). This is also required by the TNCA.

What‘s the best way to address a Fundo shower Base base cut too short?

When the base is cut too short, the best way to remedy this situation is to purchase and install a wedi base extension. Determine if the 2‘x4‘ or the 12“x72“ will suit your needs. Utilizing a wedi extension panel will guarantee a consistent slope into the base area as well as a uniform, strong coating with limited water absorption, and uniform/strong reinforcing of the floor part. This method applies for all wedi bases. Please note that, due to the need to install a new extension piece that is not too flimsy and can be 1/2” x 1/2” Z-notched correctly, those extension pieces should never be smaller than 3 inches in length. So in some cases you may want to cut the short Fundo base even shorter to have its edge at least the 3 inches away from the (framed) wall.

What‘s the best method for installing thinset to a wedi Fundo Base?

When installing the wedi Fundo base to either a wood or concrete substrate you should treat the base like a large format tile. wedi requires a min. 3/8“/ 1/2” maximum (square trowel size) of modified thinset for this application. When using a 1/2“ x 1/2“ notch trowel you can simply flat trowel the back of the wedi base, and use the 1/2“ x 1/2“ notch trowel to install thinset on the wood or concrete substrate. When using a 1/4“ x 1/4“ notch trowel you should apply thinset on both the pan and the floor with the trowel lines going in the same direction to ensure that air trapped in these lines will be able to escape. Make sure the thinset lines always point into the direction offering the shortest distance to go for the air to escape when channels are compressed forcing air to escape.

How do I install the wedi Fundo Base drain cover set?

With Primo, begin by removing the grid from the center of the drain cover frame. Next you‘ll want to tile to the frame to ensure a tight installation. Next, remove the frame, and determine the height adjustment you need to make. It‘s best to use spacers or stainless washers to build up the corners to the desired height. For thicker tile installations you should always use the black extension collar/ riser provided. Simply cut the extension collar using your wet saw, and install below the drain cover frame using wedi joint sealant on the corners only. When working with tiles that are thinner than the drain cover frame, it‘s best to determine the height you need to adjust your thin tiles. For example if you need an additional 1/8“ of height, you will need to use a 1/4“ x 1/4“ notch trowel. If you need an additional 1/4“ in height, you will need to use a 1/2“ x 1/2“ notch trowel. When the thinset is compressed you will end up with a bit of half of the thickness of the original sized trowel (thinset shrinks). Once thinset has been applied, use the flat side of the trowel and knock down the trowel lines on a 90 degree angle. This will ensure you have the proper height and will also give you better coverage when setting these types of tiles. Do not use angle grinders or similar tools to reduce the height of the wedi frame folding the cover. This is not only dangerous but may also impact structural strength of the drain cover frame.

Can I substitute wedi joint sealant with another sealant product?

No, wedi joint sealant is a proprietary product, engineered for durability and waterproofing while maintaining flexibility for the lifetime of a wedi installation.

How do I know which Riolito Neo base to use?

wedi offers 4 versions of the Riolito Neo shower bases plus Riolito Neo Modular models, that can be used in 12 different base configurations without adding an extension panel. Each base can accommodate several different sizes in one base alone. You can simply cut the base to fit the shower size you need. Provided you consider the center of the wedi drain unit to fit in the overall measurement of the shower floor area. Do not cut these bases too close to the integrated drain. Any cutting of the Riolito Neo base may proceed if the cutting line is at minimum 1 inch away from the drain channel installation panel and towards the main shower base area. Once cut to fit, the base perimeter’s notch channel (Z notch) must be recreated and be 1/2” wide x at least 1/2” deep (depends on depth of adjacent channels and model) in dimension.

What is the best way to connect my Riolito Neo drain?

When installing the Fundo Riolito trap below the base you must first locate your drain pipe. If working on concrete you will want to trace the area of the drain trap, and begin chiseling and cutting away the concrete approximately 1“ below the concrete surface. If you are working with a wood substrate, simply trace the trap template positioned (squarely) at the drain position provided and cut your plywood to allow the trap to slide into the wood substrate. Your plumbing pipe should be cut 1 1/4“ below the top of the subfloor. Once the plumbing has been dry -fitted, the drain pipe is ready to be solvent cement glued to the trap using appropriate cements. Finish installing the trap but do not use wedi joint sealant around the perimeter, and use no screws if installing over plywood, to fix the trap. Take care of securing the trap units solid support so it cannot move under water load or otherwise. Fill the drain and trough with water to ensure proper connection, do this immediately after setting the base in thinset to allow for quick adjustments if needed. NEVER walk or stomp the drain area into thinset bed. Instead, gently push in place. Ensure the drain section is fully supported by floor and thinset mortar bed. Any voids will add tension to the drain which might lead to cracks.

How do I check to make sure my base is lined up right with the trap?

You can easily check this by dry fitting the base before installing the base using thinset. Lay the base in the desired location, and gently push and tap on the base with side of your hand. Once you feel and see the pan locking into the trap, stop and pull the base out. DO NOT STEP ON THE BASE TO DRY FIT!!! IT WILL BE VERY DIFFICULT TO REMOVE (and likely end up broken). Also make sure to fully insert the male rubber gasket into the base underside before fastening it against the base for a tight snug fit all around. Make sure to use only the wedi screws provided. These are special made in Germany and cannot be replaced by any other screw in the North-American market.

What‘s the best way to install the drain cover?

After using the grey spacers that come included with the Riolito base, as a template to stop your tile install, simply dry fit the drain cover with the height adjustment spacers . Measure from the top of the drain to top of the tile (+ compressed thinset layer) + 1 mm. Next you will remove the height spacers from the drain cover, and screw them onto the spacers provided in the drain when you purchased the base. Next mark the height adjustment spacers to the measurement taken, and cut off the top side of the space once you‘ve removed the brass collar. Once cut, simply reinstall the brass collar, and slide the adjustment spacers back into place.

What is the difference between the standard Riolito Neo and the new Neo Modular?

The standard Riolito Neo bases incorporate the drain troughs in the base. The bases can be modified but you are limited to a matter of inches from the existing drain location. The new Neo Module can be installed almost anywhere in a shower, as it is a modular drain assembly. Once the Neo Module has been installed you can simply build the remaining base area using wedi Neo Base Extensions (following installation guidelines for extension panels) or dry pack mud, with the use of wedi subliner dry over the cured dry pack mud. (Follow wedi Subliner Dry installation instructions). Riolito Neo modular drain part also allows for a much easier and controlled fit to the drain trap. This is because you are closer to the connection and can see issues coming up. The part is also much smaller and lighter compared to handling a large one piece base by yourself and while trying to exactly meet up with the trap opening.

When recessing wedi Fundo Ligno for its entire 3/4” , which tile substrate and waterproofing methods for the bathroom floor outside the shower can be connected to the Ligno Base?

The lowest profile waterproofing and tile underlayment in one is the wedi Subliner Dry Sheet membrane. It is applied over a suitable structural subfloor using modified thinset (trowel size 1/4” x 1/4” square. This membrane would overlap onto the Fundo Ligno by 4”.
4 inch strips of this Subliner Dry membrane, or wedi Subliner Dry Sealing Tape, are installed as a flashing reaching 2” up the wall and 2 inches down on to the Subliner Dry membrane. The membrane will do the waterproofing and it can be tiled over right away (Robinson Floor Test rating: “Heavy (duty use)” ).
But even though you can always recess Fundo Ligno for its entire 3/4” thickness, in some cases you may want to recess less deep. Such as when cement board or other underlayments are installed over the bathroom floor. Accordingly, you would increase the Ligno in its recess by the thickness of such underlayment plus the thickness of a waterproofing layer like Subliner Dry ( to be installed over cement board, floor leveler screed, or other non- waterproof surfaces such as uncoupling plastic membranes).
As you can see, it is always possible to increase the height of Ligno in a recess. This can be done easily by installing a wedi panel or cement board with the needed thickness below Ligno.

When installing the Fundo Ligno over concrete, or not recessing a 3/4” plywood to integrate into a wood subfloor, what is the best thickness of wedi Building Panel to use for the connection of a waterproof flooring underlayment to Ligno?

¾“ wedi building panel is the best panel to use in this application. The base and the building panel will both utilize modified thinset, and will create an and even plane from the outside of the shower to the beginning of the shower base. Be sure to notch the ¾“ wedi building panel to fit tightly against the existing notch in the wedi Ligno shower base.

What thickness of wedi building panels can I use outside of the Ligno shower base to tie into the base installation?

Using ½“ is always going to be the easiest and best practice. You can use the 1/4“ building panel, but you must cut a 1/2“ wide piece to fill in the ¼“ below the board tying into the side of the pan. When using 1/8“ it‘s best to use a 1/4“ piece of building panel, followed by a 1/8“ then install your 1/8“ over top. Use wedi joint sealant to bond the strips in the channel to the base. Do not use thinset or wedi joint sealant only to fill in this notch. In those cases, Ligno has to be recessed at least to a depth comparable to the thickness of wedi Building panel used on the surrounding bathroom.

How much can I cut off of my Ligno shower base?

wedi allows for only 6“ to be cut off of any side of the ligno shower base. This is also in line with wedi‘s general recommendations for max. cutting allowances for all shower base types. This allow you to remade a Z-notch channel into the Ligno base edge which should be at least ¼” deep x ½” wide (or width equivalent to thickness of wall panel used). The remaining horizontal part of the channel be still be ¼” thick and stable.

What‘s the best way to extend the Ligno base?

The best way to extend the Ligno shower base is using our new Ligno extension panel. This will add up to 1/4“ to the height of your perimeter if the full extension is used, and you must accommodate that using appropriate thinset during your tile installation. You will need to use an extension panel when working with a shower larger than 60“ square with a center drain. You will have to determine the easiest method for your installation. A best practice should be to suggest adding a wall or knee wall in the areas where an extension is present.

Do I really have to waterproof outside of a curbless wedi Ligno shower?

Yes, the reason for this is because of water splashing outside of the shower on top of the tile, and because water will wick very easily through the thinset that was installed below your tile. wedi recommends installing the waterproofing at least 3 ft out from the shower entrance but if water may be present beyond that , or if space is commercially used or in ADA related installations, we recommend to waterproof over the entire bathroom floor outside of all curb less showers. Additionally, waterproofing up the wall is just as important outside of the shower. A min 2“ high (sealing tape) of wedi Subliner Dry or wedi building panel should be used to waterproof this connection as sheetrock, and backer boards will absorb water causing failures. Liquid applied waterproofing is NOT recommended for waterproofing between wedi and the outside substrate, or over the cement board on the bathroom floor.

My wedi niche is not the size I need, can I modify the height and width?

Cutting flanges off wedi niches and combining them to create a larger niche would be the easiest and most reliable option if you wanted to enlarge a niche vertically. The two niches have to be sealed together and reinforced using wedi joint sealant. Additionally, if you want to extend horizontally if there is a stud in the wall where the niche is being installed, combining two wedi niches where the flange goes over the stud creating a vertical separation can also be implemented as well.
Reducing niche openings can also be done by inserting/ gluing a bottom and top strip of two wedi 1/2“ pieces ( laminated to a 1“ piece).
These spacers are set back 1/2“ from the front face of the niche. Another ½“ wedi panel piece needs to be attached as front cover over the spacers.

Can I install a wedi suspended seat after the tile has been installed?

Yes you can, simply mark where the seat will be installed. It must be installed in a corner and on both wall sides two studs must be present at 16” o.c. or less so the seats mounting brackets can be installed into two studs later. Cut out your tile, and try to not destroy the wedi panel (or another backer panel) below. If needed, reinstall your wedi building panel (or a different backer panel), using wedi joint sealant around the perimeter of the area removed. Make sure the new panel going back is cut tight and cleanly.
After installing into the new joint sealant, more sealant needs to be added around the inside perimeter to ensure a proper seal. After 30-45 mins you can install the cleats of the suspended seat. After that use wedi joint sealant to install the suspended corner seat. In this case the tile should be installed with a pitch to offer water a slight run off the seat. (or this is done with the seat and when tile is cut out)

Can I install benches or countertops out of wedi 2” thick panels and do I have to treat the blue foam edge(s) prior to tiling?

Yes, benches and seats and many more installations such as these can be installed without framework needed. These panels can be cut and fitted together, using wedi joint sealant. When a blue , exposed, foam edge remains , such as at the front of a wedi 2” panel used as a countertop, a strip of wedi panel, 2” wide, can be glued to this edge and will restore a cement resin coated “wedi panel surface” prior to setting tile. Any wedi building panel can be used for making such strips. Most easily this is done with wedi 1/8” building panel. The area which is covered by such strip should be cut back while the element is installed so that the strip is flush with the entire surface.

Can I install a seat build from the floor up after the tile been installed?

Yes, use 2“ wedi building panel to install a seat after the installation of tile. Simply dry cut your boards to the desired height and width. Use wedi joint sealant to bond the board to the tiled walls and floor. In addition, install wedi joint sealant around the perimeter using a standard caulk joint size and your finger. This will keep the sealant off of the tile and give you the needed sealed joint around the perimeter as well. Over very smooth tile please use general primer to using wedi joint sealant.

Can I build a floating seat out of 2” board?

Yes, build a floating seat up to 18“ in length on the walls. This can be made using a minimum 2“ thick wedi panel. Two of these panels can be glued to 4“ or thicker if needed. Use wedi joint sealant to bond the panel to the wall, but make sure the joint sealant is spread over the entire contact surface between wedi seat panel and wedi wall. You should use a fine tooth adhesive trowel with minimum 1/8” x 1/4” notches. All seams from seat to wall (on top of seat and below) shall be sealed over widely (1” either side of seam) using wedi joint sealant and a putty knife. Once this sealant has set, use wedi alkali resistant, and self- adhesive, mesh tape over the seams of top of seat to wall prior to tiling.

When building a seat from the floor up, it‘s best to apply standard framing practices. Install vertical support panels (2”) against walls, as sides to the seat, and for the front. wedi 2“ wedi building panel is also installed, within the seat construction, every 18“ for support. Include a sloped top (slope may be fabricated using wedi joint sealant wet shims or by cutting all supports accordingly) . After sealing and reinforcing the seams in the assembly, as well as seams between seat and wall with wedi joint sealant, you may have additional blue foam exposed. Simply key in thinset over these areas or install a wedi panel strip over these using wedi joint sealant. Cutting areas back to have them covered with a strip that is flush with the seat surface should considered when cutting and dry-fitting the seat assembly. A wedi building strip to cover exposed blue foam is definitely needed when the tile in this area will not overlap from the blue foam area onto the cement coated seat area (such as when working with mosaics). When building floor standing seats or benches in wert areas and over sloped surfaces, the front vertical seat panel will show a gap to the floor surface. This gap shall not be filled with sealant but should be backfilled with thinset mortar for strong support. wedi mesh tape is used in this thinset mortar application for reinforcement. When installing such seats or benches against areas which may be tiled already, or walls made of cement board or EPS panels, or which may, for any other reason(s) potentially allow water to enter the seat (e.g. from below wall tiles) it must be ensured it will not get stuck in the seat. The mesh and thinset cover over the front panel gap will allow water to exit. But if the floor was already tiled, and the use of thinset and mesh is not possible, it will be a good measure to drill a few relief holes into the bottom areas of the seat before tiling.

Can I use screws in the top of my curbs, seats and knee walls?

No, the best practice here is to use thinset to bond your wedi building panel to your wood framed seat, curb, or knee wall cap. On smaller areas, and very flat areas such as the top of a knee wall or curb wedi joint sealant can be used to bond the wedi building panel to the wood framing.

Can I modify my full foam curb? If so how much?

It is best to not cut the full foam curb less than 2“ wide and 3 1/2“ tall. When cutting the full foam curb, it‘s best to cut from the bottom as the top of the curb is sloped.

Do the seams in an installation have to be treated?

Yes, all seams should be treated. The best method is to treat with wedi joint sealant. In cases where waterproofing is not needed such as on a floor outside of a wet area, wedi self-adhesive, alkali resistant fiberglass mesh tape or wedi sealing tape, can be installed using modified thinset mortar to provide a continuous bonding surface. In wet areas wedi joint sealant is the recommended application. Do not add any mesh in the bed of wedi joint sealant except where you need to apply sealant over off angles and transitions. Here you want to use the mesh to provide a better surface for the sealant application. Mesh or any other tape, when added in joint sealant or thinset mortar, does not add additional protection against movement. Tears due to movement happen as cohesive failures between a substrate and the directly bonded material (joint sealant or thinset mortar). Once this is done, the failure cannot be reversed by any presence of mesh or tape. Sealing tape of mesh embedding in thinset will render the flexibility value of such tapes or meshes useless as they are packed into an inelastic material. Mesh and tape usually add only disadvantages such as difficult to tile over higher build up in corners and transitions, or the possibility of water intrusion along mesh lines or through thinset mortar underneath a tape.

Mesh, in the perception of some manufacturers, supposedly acts as “rebar “ or reinforcement for sealants. The perceived benefit would be a better protection against movement. Physics and testing, however, show a much different picture: movement of concrete or wood substrates capable of tearing on sealant to a point at which the mesh is reached or may go into action will have caused tremendous damage by that time. The embedding of mesh in two layers of sealant provides for a sealant bed of a minimum of 1/8”. Sealants of wedi’s class have an elongation potential of about 200-250%. This means they could in this case stretch to about a 1/4” - 5/16” before breaking. The mesh may now prolong this effect. But once a seal or seam is pulled apart by a 1/4” , tremendous damage is done to any installation including wedi systems, mud bed/ liner showers, sheet membrane covered shower products. Therefore it is highly unnecessary to add mesh and the recommendation to add mesh is misleading installers to trust in a perceived benefit that cannot materialize.

When installing the wedi Subliner Dry sheet membrane systems you would want to use the wedi waterproof sealant tape to treat seams or you may overlap the membrane sheets by 2”, thinset mortar applied between overlaps or under sealing tape . However, wedi joint sealant will later be spread and sealed over any exposed seam so water may not wick into thinset mortar between membrane sheets. , follow wedi installation instructions accordingly. To avoid excess thinset mortar at seams and transitions or terminations of our membrane, it is recommended to fold the membrane edge back by 1” and tape into positions. Use joint sealant to glue the edge area down , then seal over the area with joint sealant again.

When working with wedi shower systems, there is no substitute for wedi joint sealant, a sealant and adhesive made under wedi license- and developed by wedi. One of the key important points in a successfully waterproofed shower installation is to safely seal protrusions and installations going through the waterproof walls. Shower valve, shower head , body showers and many other items are very often not appropriately sealed into the system. Water, running below the tile kevel through thinset mortar will find these areas and may easily leak outside the shower. Once the water has exited it may start to compromise the subfloor and/ or framing outside the waterproof shower enclosure. Once the wood structure starts warping or swelling it will start to destroy the shower and previously waterproof installations from the outside going in. It is extremely important to use sealing products such as wedi’s Flexi Collar ( Valve or Shower Head) to address these issues safely. The plumber, when installing seals on his own , will not install protection against the water running behind the tile.

What is the best way to waterproof showers that already have sheetrock or cbu?

wedi Subliner Dry is the perfect product for addressing this situation. Simply install the Subliner Dry over the sheetrock or CBU using modified thinset. When installing over CBU, first add water to the wall using a sponge to ensure the CBU doesn‘t absorb moisture too quickly, from your thinset causing bond failure. Drywall should be primed. You should use wedi Subliner Dry inside and outside corners as well as wedi waterproof sealing tape in the corner(s) from floor to ceiling and at the wall pan connection.

What is the best way to seal off shower valves and plumbing fixtures?

When sealing off valves and plumbing fixtures, it‘s best to install wedi prefabricated flexi valve covers and collars prior to tiling. Custom valves and protrusions can be addressed using wedi Subliner Dry, cut to fit tightly around protrusions or covering cut outs for valves. A bead of wedi joint sealant describing a semi- circle over the valve area will help divert water sideways off the valve area as it will interrupt the thinset bed carrying the water flow giving the water new direction.

What‘s the best thinset to use with Subliner Flex?

Modified thinsets are recommended for use with all wedi products.

Can Subliner Flex be installed over an expansion joint in concrete?

No, you must carry expansion joints through the Subliner Flex and through your tile installation as well, by using a soft joint above the expansion joint.

How do I prepare the wedi 2 part epoxy vapor barrier for installation?

Begin by making sure the vapor barrier has not passed the expiration date printed on the label. Next you will need to unseal the can and remove the black or red button on top of Part A. Poke a hole in the seal, and turn the epoxy upside down. Allow the part A epoxy to drain into part B. Make sure all of the part A has drained into part B. Once completed, use a metal polished stainless (PS) jiffy blade mixing paddle to mix the 2 part epoxy for 5 mins on low speed. This needs to be completed in the same container the product is sold in. Next, immediately pour the epoxy into another metal container such as a metal paint tray; remix one more time before installing product on the walls. DO NOT USE ANY PLASTIC MIXING PADDLES, OR PLASTIC PAINT TRAYS AS THESE WILL HAVE AN UNWANTED RESULT. DO NOT ADD MULTIPLE UNITS WHEN MIXING AND WORK WITH ONLY ONE MIXED UNIT AT A TIME. Apply product to all interior wedi building panel surfaces, but not the floor, only. Make sure at least two coats have been applied. In addition, tiling MUST be completed within 5 days of installation. If tiling has not been completed within 5 days, more epoxy must be applied over the exposed area after scarifying the old epoxy surface, and remaining tiling must be completed within 5 days.

Is tiling directly to the blue foam approved?

It is not generally approved or endorsed. However, you may tile right over and  overlap onto seat top edges and similar exposed foam edges of wedi construction if the tile is also bonded with at least 50% or more of its surface to a wedi cement surface.

Is it possible to install a floor heating system on top of the wedi Shower Base?

Yes, this can be done, but it’s not recommended (wedi bases are insulating and naturally warm up fast). The build-up is messy and it adds height that may interfere with our slope and our drain cover height. All such heating systems must be wet area rated, and be topically waterproofed after installation so there isn’t a permanently soaked area on the wedi surface. This would create the risk for dark and discolored grout and stone tile.

What is the maximum amount that can safely be cut off of the 3’x6’ offset shower base on the side with the drain?

Safe areas to cut are those beyond the metal ring on the Fundo Primo’s underside. In addition, you want to ensure that you have enough surface area left to re-notch the base after cutting to accept wedi Building Panel for the wall in that notch. Plus, you might need to accommodate for wall tile thickness, and/or a bit of tiled surface on the shower base between such wall tile and the drain opening. However, the slope design will be affected by all cuts made, and may be unaccommodating to the tile or design pattern, and this should be considered.

When attaching the ABS Riolito drain assembly to the PVC pipe, what specific glue is the recommended to attach the drain assembly to the PVC pipe? Does it need to be installed by a certified plumber because it is being glued to the pipe?

State or local code may require a licensed plumber to do these jobs. Same with joining ABS to PVC. This is not always allowed, however that position is a bit old. Nowadays, it is widely accepted that ABS and PVC will be OK when joined with a multipurpose cement (must say for use with PVC (CPVC) and ABS).

Is it acceptable to use the Ligno shower base in conjunction with the wedi Ramp by cutting the ramp down on a floor that is not recessed in order to get a lower profile ramp?

Yes, you could do that, if the remaining ramp area is still acceptable considering the intended use. For example if the installation has to be ADA compliant.

Can the curb be cut down in height from the bottom as long as the notch is re-created to interlock with the shower base? Do we have a minimum height requirement that the curb has to be above the shower base?

wedi doesn’t have a minimum height requirement. Any height exceeding the height of the shower bases perimeter edge would be acceptable. However, most local building codes require finished curbs to have a height of 2” above the drain cover. It should always be considered that the curb needs to be tiled on the inside and outside poritions for this to be finished perfectly, the installer might need a minimum surface and height available. 

How are door U tracks mounted or fixed to a wedi foam curb?

Tracks are fixed with epoxy adhesives. Any mounting devices that need screws will not be able to anchor in wedi foam. For this, you would want to glue a 4”x4” galvanized or zinc coated metal sheet (1/16” thick) onto the curb where you plan to screw into the curb. Use non-corrosive self-tapper screws for this.

When using the wedi Subliner Dry sheet waterproofing membrane to waterproof existing wall board in a shower, like cement or fiber cement board, while using the wedi base, how far does the Subliner Dry need to extend on to the shower base?

A minimum of 4” would be considered safe and gives you some surface to work with without stretching the material at the corner too much.

When installing a heated floor outside of the shower, what is the proper way to waterproof over these heat systems? (Including the waterproofing over those underlayment systems with uncoupling features, and also how to create the waterproof transition from inside of the shower to the floor outside of the shower using the wedi Subliner Dry sheet waterproofing membrane.)

wedi Subliner Dry and it’s required flashings (wedi Sealing Tape and Inside/ Outside Corner tapes) would need to be installed over these systems and overlap 4” into the Ligno. However, these systems manufacturers might not warrant wedi Subliner Dry installed over them. No warranty from wedi alone can be offered here, due to the variety of underlayment systems available. wedi does, however, warrant the use of Subliner Dry over heating systems safely integrated in cement based leveler and screed applications and underlayments.

When installing wedi Subliner Dry waterproofing sheet membrane on the walls of a shower (for example, over cement or fiber cement board) is it mandatory to use the Subliner Dry Sealing Tape on the inside corners or transitions and changes of plane, or is it acceptable to flash the larger roll onto the adjacent wall or onto the floor area?

Yes, it is acceptable to flash the larger roll onto the adjacent wall or onto the floor area.

When adhering a 2” thick wall to a wood or concrete floor and the wall panel, would I use Thinset Adhesive or wedi Joint Sealant?

On all wall connections, wedi Joint Sealant is used when adhering to wedi walls. Both, wedi Joint Sealant and Thinset Mortar can be used when adhering such freestanding wall to floors. Joint Sealant is applied in a straight line ½” thick centered on the wall or floor contact surface of the 2” panel. For thicker panels, Thinset Mortar is used.

What is the best way to waterproof a wall that has a window in the shower? What about a window that extends right next (or close) to the shower base?

There’s no good way doing this safely. Every window is different and will often just provide for a butt seam to be filled with sealant. An example of providing extra protection could be by adding PVC T profiles if they fit the design of the connection to the window (T profile as in floor transition profiles) into such seam and sealant behind the horizontal parts of the T. This better allows to seal to a window frame without anyone seeing the sealant of the window frame’s surface. There is no good standard response, however, that works in all situations. Please contact wedi to discuss such installation detail.

When is mesh tape needed on top of an exposed blue foam prior to tiling that edge vs. putting wedi Building Panel on top of the blue foam using wedi Joint Sealant?

You can install mesh and wrap it around such edge tightly, then Thinset it later. You can use the wedi Building Panels. We prefer using wedi Building Panel strips or 1/8” wedi Building Panel as a best practice. It is faster, cleaner, and likely on hand and available on your project site. It would be adhered using wedi Joint Sealant.

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