Weber - Weber Set WF21

Weber - Weber Set WF21

For fixing ceramic and porcelain tiles:

- Floors only
- Interior and exterior situations
- Where movement is expected
- To difficult surfaces
- Suspended wooden floors:
tongued and grooved timber
tongued and grooved chipboard plywood
- Underfloor heating (heating within screed)

Constraints
Not suitable for heavy duty floor use or for floors with an electrical radiant heating system.
A two-part, dark grey, flexible, ceramic wall and floor tile adhesive, for interior and exterior use on backgrounds where movement is likely

About this product

weber.set WF21 is a two-part, dark grey, highly flexible, elastomeric ceramic floor tile adhesive, for interior and exterior use. It is used for fixing most types of tiles where some movement of the substrate is expected.

Features and Benefits

- Manufactured under BSI Quality Assurance Scheme ISO 9001
- Suitable for use on backgrounds where movement is likely
- Fixes ceramic, mosaic, quarry, marble, terrazzo and terracotta tiles, and brick slips, to most building substrates
- Suitable for timber, plywood, flooring grade chipboard and insulating floating floors
- Can be used to fix to steel and mastic asphalt
- Suitable for light floor traffic after 5 hours (at 20°C)

Preparation

Ensure that all surfaces are clean, dry, sound and free from dust, grease or any other contaminating barrier. Make good any unsound areas and remove all flaky or peeling layers before tiling.
Prime porous or dusty surfaces with weber AD250 and allow it to dry.
Check before use that the colour of the adhesive does not cause staining or discolouration of light or translucent tiles.

Mixing

Never use water. Shake the WF21 solution in its bottle and then pour it into a mixing bucket. Add WF21 powder gradually to the liquid and stir thoroughly until a smooth lump free mix is obtained. Use all of the solution with all of the powder. If a part pack must be mixed, care should be taken to maintain the original mix ratios.

Use the wet mix within approximately 40 minutes after mixing. Do not attempt to extend the pot life by adding extra solution or water to the mix.

Application

Do not use at temperatures below 5°C.
Apply the adhesive onto the substrate covering up to 1 m2 at a time (or no more than can be tiled within 20 minutes).

Use a suitable notched trowel to achieve a bed of thickness of at least 3 mm. Large or studded-backed tiles may need to have adhesive buttered onto the tile back as well. Where large tiles are being applied to a nonrigid substrate, the bed thickness should be 5 to 6 mm.

Bed the tiles firmly into the adhesive with a slight sliding and/or twisting action to ensure a good contact.

It is good practice to lift an occasional tile after fixing, to verify that the required contact has been achieved. In wet areas, external areas and all floors the final adhesive bed should be free from voids. Leave appropriate clearance joints for grouting and make any adjustments within 10 minutes. Carefully clean off excess adhesive from the tiles and joints before it dries.

Under normal conditions the joints can be grouted after 5 hours. At lower temperatures and if tiling onto an impervious surface, the setting time will be extended.

Existing ceramic/vinyl tiles
Ensure that the tiles are firmly adhered, clean and free from polish, wax or detergent. Replace any loose tiles. The floor must be capable of supporting the additional load without undue deflection.

Mastic asphalt (interior only)
Ensure the surface is sound, clean and dry and of adequate cohesive strength and of a flooring grade. weber.set WF21 can be applied over small amounts of existing vinyl tile adhesive residue, providing that is clean and well attached.

Steel
Ensure that the surface is clean and free from grease. Remove any traces of rust and prime with a zinc chromate primer.

Wood/timber
Wood should be at least 18 mm, ventilated beneath and strong enough to support the weight of tiling. It should be rigid enough to give no noticable deflection under walking loads.

Plywood and chipboard should be of a water resistant grade.
Prime new boards on the back and edges with weber AD250. Priming of the surface to be tiled is not necessary, but will help to reduce distortion of the wood from the moisture in the wet adhesive mix. All board edges must be supported, either by tongues and grooves in the boards themselves or by joists or noggings underneath. Screw boards to the joists at least every 300 mm. In the case of tongued and grooved timber screw both edges of each board to every joist. For floating floors the boards must be glued together and the sub-base must be rigid and stable.

Allowance for movement

Flexible joints should be incorporated to allow for slight movements due to changes in temperature, humidity etc. as indicated by BS5385:
a) where the tiling meets other materials (e.g. floor perimeters)
b) along all internal corners – vertically and horizontally
c) over existing movement joints or changes in background material
d) dividing large tiled areas into bays (every 3 – 4.5 m on walls, 8 – 10 m on floors)loads.

Health and Safety

Powder component contains cement. Liquid component essentially non-hazardous.
For full information on Health and Safety, please see inside back cover.

Technical services

Weber’s Customer Services Department has a team of experienced advisors available to provide on-site advice both at the specification stage and during application. Detailed specifications can be provided for specific projects or more general works. Site visits and on-site demonstrations can be arranged on request.

Technical helpline

Tel: (01525) 722137
Fax: (01525) 718988

Storage and Shelf life

Powder: When stored unopened in a cool, dry place at temperatures above 5°C, shelf life is 12 months from date of manufacture.
Liquid: When stored airtight in a cool, dry place at temperatures above 5°C and protected from frost, shelf life is 12 months from date of manufacture.

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