FAQ - Fundo Ligno

Frequently asked questions on wedi Fundo Ligno Shower Bases

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.

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