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Tiling on gypsum plaster

 

 

Case

Gypsum plaster can only withstand relatively small/light tiles

Gypsum plaster work should be firmly adhered to its substrate and sufficiently strong to support the specified tiling.

Gypsum plaster is a relatively weak material (in comparison to wood, block work, concrete or other cementitious material). The maximum weight of tiling acceptable on a dry, well-adhered plaster background is of 20 kg/m². Plaster work should be completed at least 4 weeks prior to starting the tiling job. Even if the surface appears to be dry in less than 4 weeks, the layers underneath may not be properly dry nor fully cured.

 

 

Gypsum plaster is water sensitive

Gypsum plaster is water sensitive and is therefore not an ideal substrate in wet areas such as bathrooms, showers, kitchens or wet rooms

Inconsistent quality of finishing

The finished surface of gypsum plaster can be inconsistent and varies depending on the surface conditions and the workmanship.

The surface can be very dusty or, if over trowelled, it can be very dense and shiny.

Cement based adhesive react with gypsum plaster

When gypsum plaster comes into contact with cement, it forms a weak layer of ettringite that can cause the adhesive and plaster not to adhere properly. Careful preparation is needed to prevent this from happening.

 

 

Solution

Substrate preparation

The substrate must be sound, clean and able to bare weight, free from dust, dirt, grease, oil or any contaminating materials prior to fixing tiles and prevent adhesion failure.

For waterproofing over gypsym, apply 2 coats of acrylic waterproofing membrane

weberdry gum with the use of weber band embedded in the 1st coat (in all corners and sensitive points).

Method of application

Tile adhesive

Apply webercol paste, a dispersion tile adhesive, uniformly on the support and use the notched spatula to give the required thickness.

Apply the tile and press them strongly on the substrate in order to spread the product uniformly on the walls.webercol paste can be used over gypsum substrat without any primer. 

Tile grouting

It is recommended to have a minimum joint width of 2 mm around the tiles. Grouting should be done at least 24 hours after fixing tiles, using weberjoint perfect or weberjoint deco. Apply with a rubber trowel in a diagonal direction to completely fill the joint. Remove excess material from the surface with a damp sponge. When the grout is dry, clean it with a dry cloth.

Important note

Gypsum plaster loses nearly its cohesive strength when wet, so it needs to be protected in

areas where it could be subject to wetting such as wet areas.

Therefore a protection is required when application in wet areas.

 

 

 

 

Solution with the following weber products

Solution

weber.col prime

Primer before tiling on difficult substrates

webercol plus

High performance cementitious tile adhesive (latex modified)

Solution

weberjoint perfect

High performance, Low Stain, cementitious tile grout with Hydro Repell and Mould Stop technologies

weberjoint/ weberjoint thick

Cementitious tile grout

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