Heavy Tiles and Liquid Membrane - Can They Work?

rymass

Hi Everyone,

Happy New Year! Hope someone can shed some light on this for me. I'm re-tiling our wet room and have covered the walls in XPS foam/cement backer boards. These were recommended because the tiles we are using are large format, heavy-ish, and need to be able to stick to the wall properly.

I'm planning on using a paint on membrane in the shower area to help with waterproofing, however, what concerns me, is that will the tile be able to stick to the backer board (properly) if it has a membrane painted over it? I understand this is fine for wall tiles, but what about 60cm heavy-ish floor tiles being used on the wall? Will the membrane lessen how heavy the tile can be?

Thanks, Ryan

Rows Grower

The paint on membrane is specifically designed to accept tile adhesive and should come with a lifetime warranty once instructions are followed. The backer board will be more likely to fall off if not fixed properly, that is assuming the tiling work itself is done properly.

10-10-20

I'm not a tiler, but I had a look at the spec sheet for the Mapei tanking product to see if a shear value or adherence pressure was stated but it's not.

https://cdnmedia.mapei.com/docs/librariesprovider12/products-documents/1_00186_shower-waterproofing-kit_en-gb_01391f20f3e143ef971e2b0471564ccb.pdf?sfvrsn=1b8f3efd_0

I believe that how it works is that as the tanking compound is applied as a thin coat (0.8mm wet, 0.5mm dry) and given that it has a very good adherence to the substrate surface (providing that the spec sheet is followed), it carries over the effective strength of the substrate. Clearly dust and moisture will affect that adherence, so the prep is key.

That's my understanding of it - open to correction.

Le shovelle

The adhesive will stick to the membrane no problem.

On a side note: when using large format tiles, it's recommended to butter a thin layer of adhesive onto the back of the tile as well as coating the wall.

rymass

Hi all, thanks for the valuable info. Backer boards should hopefully not fall down :) (tiles may be a different story as I'm not too experienced). But I've used adhesive and mechanical fixings to keep the boards strongly in place. Will be reading the spec sheets of several membrane products before I use them

Mellor

https://www.boards.ie/discussion/2058278695/heavy-tiles-and-liquid-membrane-can-they-work

Cement boards are ideal. Adhesive won't be an issue of the waterproofing, its literally what it's purpose is. But not sure why the XPS is there. I'd be concerned about that rather than anything else.

Also, bare in mind that large format tiles are no heavier, per sq.ft or sq.m than smaller tiles

10-10-20

https://www.boards.ie/discussion/comment/120088234#Comment_120088234

It's probably these cement layered XPS boards. I used them instead of ply for floor tiles recently enough.

https://www.goodwins.ie/products/Botament-Tile-Backer-Board-4mm-1.2-x-0.6mtr.html

Mellor

I used “soft” board under floor tiles before. But for walls I always go with rigid FC. Although, the description say it’s fine for walls too.

10-10-20

https://www.boards.ie/discussion/comment/120089231#Comment_120089231

There is less flex in these than 12mm plasterboard anyhow. I was impressed as they are easy to work with.

rymass

That's exactly the ones I have 👍. I checked with the local building supplies store and they said the tiles won't fall off with the tanking membrane - As long as they are not extraordinarily heavy tiles. Mine are only 60cm X 30cm. But are floor tiles which I liked the design of .