weber.xerm 858 BC Tile Adhesive - Weber

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Weber Saint-Gobain - Official website of the company

weber.xerm 858 BC Tile Adhesive

weber.xerm 858 BC Tile Adhesive
weber.xerm 858 BC Tile Adhesive

Product benefits

  • For wall and floor
  • Optimised processing characteristics
  • Increased performance

Thin-bed and medium-bed tile adhesive for universal implementation with high-performance and climate- protecting BlueComfort technology.


Product description

weber.xerm 858 BlueComfort is a factory-mixed, flexible thin-bed and medium-bed tile adhesive in accordance with DIN EN 12004.

Composition: Mineral binder, selected aggregates, additives

Product features:
• EMICODE EC 1PLUS: very low emission of volatile substances
• Extremely long adjustability period
• Excellent non-sag qualities, high bonding strength
• For interior and exterior use


Send or download the documentation

You can either send the documentation to en-email address, or download it.

Product Properties

Product specification

Declaration of Performance/DoP
Nr. DoP-DE-xerm 858 BlueComfort

Application tool Smoothing trowel, notched trowel or medium-bed notched trowel
Pot life Approx. 2 hours
Open time Approx. 30 minutes
Open to pedestrian traffic After approx. 24 hours
Open for grouting After approx. 24 hours
Open to full service After approx. 7 days
Application temperature 5°C to 30°C
Temperature resistance -20°C to 70°C
Adhesive bed thickness To 10 mm
Consumption 4 mm: approx. 1,5 kg/m2
6 mm notch: approx. 2,0 kg/m2
8 mm notch: approx. 2,5 kg/m2
10 mm notch: approx 3,0 kg/m2 medium-bed notch: approx. 4,3 kg/m2
Water requirement Approx. 6,25 litre per 25 kg

Usage area

weber.xerm 858 BlueComfort is suitable for laying ceramic wall and floor tiles, mosaic, stoneware quarter bricks, fine stoneware, earthenware and split tiles, glass mosaic, hand-formed stones, brick tiles, lightweight, fibreglass and expanded polystyrene boards, as well as natural stones that are not vulnerable to discolouration, on concrete, renders, cement screeds, calcium sulphate screeds, poured asphalt (interior), masonry, clinkers, tilebacker boards weber.sys 834, gypsum fibreboards, gypsum sandwich-type plasterboards, gypsum building boards and cellular concrete using the thin or medium-bed methods. In particular the highly-flexible tile adhesive is used on critical substrates that are exposed to slight tensions or light vibrations.


Pre-treatment of substrate

• The substrates must satisfy the requirements specified in DIN 18157.
• The substrates must be sufficiently solid, sound, clean, dry, dimensionally stable and free of adhesion-impairing substances. Concrete substrates must be free of cement laitance. Oil, grease, wax and care agent residues must be completely removed. We recommend weber.sys 894 as oil and grease cleaner.
• Old or fouled asphalt substrates must be mechanically roughened. Clean, sufficiently sanded asphalt screeds can be coated over with- out a primer coat, otherwise asphalt screeds must be pre-treated with weber.prim 803. Chalky paints as well as solid lacquer and dispersion paints must be removed mechanically.
• The surfaces of calcium sulphate flow screeds must be sanded, cleaned with an industrial vacuum, and then primed with weber.prim 801.
• Absorbent substrates must be pre-treated with weber.prim 801 and non-absorbent, smooth substrates (indoors) must be pre-treated with weber.prim 803.
• For installing tile on tile (indoors) a primer is not necessary for standard residential use. A scratch layer application must be executed on wall surfaces. In commercial areas priming with weber.prim 803 is necessary.
• The necessary substrate pre-treatments must be adapted to the specific conditions for each construction site.

Directions for use

• Do not use material that has already stiffened.
• All characteristics are based on a temperature of +23 °C without draught and a relative humidity rate of 50 %.
• Higher temperatures and lower humidity accelerate, lower temperatures and higher humidity delay the course of the reaction.
• For installation of natural stone slabs or artificial stone slabs comply with the installation  recommendations provided by the respective manufacturer. Preliminary tests must be performed if there is any doubt.
• Metal and wood substrates must be prepared through suitable measures before installation.
• For installation, the instructions specified in DIN 18157, the current ZDB leaflets as well as the applicable regulations must be complied with. The respective maximum residual moisture of the substrate at the time of installation should not be exceeded.
• Do not install tiles, slabs, or natural stones that have been stored damp, wet, or too cold.
• For bonding tile on tile in outdoor areas, and in areas that are permanently wet or permanently under water (without water- proofing), we recommend the highly-flexible 2-comp. reactive resin adhesive weber.xerm 847.
• For installation of ceramic coverings and natural stones on lightweight concrete substrates, we recommend weber.xerm 854, modified with the flexibilizing powder weber.xerm 849. Suitability of the natural stones must be verified via preliminary tests.

• When levelling substrates with lower levels of compressive strength and bulk density (e.g. lightweight plasters, cellular concrete, etc.) or when levelling calcium sulphate screeds, the maximum adhesive bed thickness of 3 mm should not be exceeded.
• When installing glass tiles or glass mosaic, comply with the application guidelines provided by the manufacturer. Colour differences can occur even with proper application.
• The adhesive can also be used on the solid-bonded waterproofing compounds weber.tec 822, weber.tec 824, weber.tec Superflex D 2 or weber.tec 827/827 S, as well as on the waterproofing foils weber.tec 825/826 and the acoustic membrane weber.sys 832.
• For installation of translucent tile materials in wet-duty areas we recommend the use of weber.xerm 854.


• Pour the specified amount of gauging water into a suitable container. Then add powder and stir until  lump-free with the stirrer weber.sys N° 1 or N° 8.
• If required the mortar can be stirred up with the trowel or the stirrer without adding more water.
• Apply a contact coat on the substrate with the smoothing trowel, then comb down a uniform adhesive bed with the notched trowel at an angle of 45°-60°.
• Before a skin forms (check the tackiness of combed down mortar with the finger) slide the tiles into the fresh mortar bed and press them on. The joints must be scratched out before the tile adhesive
• Mortar residues should be removed in fresh condition using a wet sponge. Clean equipment with water immediately after use.

Health & Safety

Quality control

weber.xerm 858 BlueComfort is subject to constant quality control via self-monitoring in accordance with DIN EN 12004.


Since there are different conditions and requirements that apply in any case, Saint-Gobain Byggevarer AS cannot be liable for other than the information provided in this product datasheet. Examples of information and conditions beyond Saint-Gobain Byggevarer AS’s responsibility (if specially pointed out or not), involves storage, construction, preparation, how the product works together with other products, workmanship and locale conditions. The information provided in this product data sheet is based on our current knowledge and experience about the product. All of the above information must be considered as guidelines. It is the user’s responsibility to ensure that the product is suitable for the intended use, and also to perform acceptance check and self-inspection control. The user is responsible if the product is used for purposes other than recommended or for improper installation.