1K sealing membrane

1K sealing membrane
  • For interior use
  • Waterproofing prior to installation of ceramic tiles
  • Ready for use
  • Crack bridging, anti-fracture membrane
  • ETA Approved for wet rooms
  • Smooth and easy to apply
  • Approved for radon protection

Product calculator

Product facts


Alfix Sealing Membrane 1K is a liquid, 1 part, ready-mixed waterproofing membrane based on polymer dispersion.




Approx. 2.0 kg/m² per mm coat thickness.


4 kg, 12 kg and 20 kg plastic buckets.



Expected Result



Surface preparation

Fixing dowels



For sealing around floor drains, use self-adhesive Alfix Drain-mat. Remove half the protective silicon paper along the perforated line and subsequently fix to substrate and gully installation. Degrease gully flange before overbridging with drain mat. Remove any clam ring!

In junctions between wall and floor, for internal vertical corners, and around pipe penetrations or sanitary installations, use self-adhesive Alfix Seal-Strip. Application of Alfix Seal Strip is made by folding the strip together along the longitudinal cross cut and subsequently removing the protective silicon paper along the perforated line. Press the strip firmly to the substrate.
Alternatively, use Alfix Reinforced Strip bedded in sealing membrane.

For bridging over cracks and for reinforcing joints, use Alfix Reinforced Strip bedded in Alfix Sealing Membrane 1K.



Alfix A/S H.C. Oersteds Vej 11-13 DK-6000 Kolding alfix.com
Alfix 1K
Declaration of performance
No. 17

Tile fixing

Tile fixing

For tile fixing, use Alfix LetFix Universal, Alfix LetFix, or Alfix CombiFix depending on substrate and tile.


Etag 022 part 1 and 2
Emissionsanalysis according to Emicode og SINTEF


Technical data

Working temperature

Min + 10°C

Density ready mixture

1.4 kg/litre

Tile fixing

Usually after 24 hours at +20°C

Curing time

7 days at +20ºC

Tensile adhesion strength concrete :

0.8 – 1.2 N/mm²

Temperature resistance

+ 60°C

Shelf life

Min.12 months in unopened container. Keep protected from frost

How to use


Cement/sand rendering, older than 2 days
Concrete, older than14 days, max. 90% relative humidity
Lightweight concrete, max. moisture content 8%
Aerated concrete
Screed, older than 7 days
Existing tiles and terrazzo.
Plywood,only floors. Max. moisture content 7 - 12%
Gypsum plaster, fibre-reinforced plasterboards, plasterboards.
Cementious boards suitable for wet room use.

Surface preparation

The surface should be dimensionally stable, sound, and clean. Free from laitance, grease, and dust. There should be no blooms, crack formations, or residues from form oil.
All absorbent, moisture-sensitive surfaces, such as rendering, brick work, aerated concrete, concrete, light-weight concrete, screed, cementious boards should be primed with Alfix Sealing Primer, diluted 1:1 with water.

Plaster boards for wet room use and fibre-reinforced boards should be primed with Alfix Sealing Primer undiluted to full coverage.

For other wet room boards, please consult our Technical Services Dept.
Plywood, floors only should be primed with 2 applications of Alfix Sealing Primer; first coat should be applied diluted 1:3 with water. Second coat applied undiluted.
Existing tiles and terrazzo should be cleaned with Alfix Deep Cleaner.

How to use

With use of roller, brush or 4 x 4 mm trowel, apply membrane to the surface in a layer of approx. 1 mm ensuring full coverage of the area leaving no voids beneath.
The best result is achieved when applying 2 coats: first coat is thin and pore-filling; second coat ensures full coverage. Any subsequent application should be made with 4x4 mm notched trowel. Complete by smoothing the surface with straight trowel edge. Ensure that Reinforcing Tape and Seal-Strip are completely over-bridged.

Drying time after first coat: 3 hours
Drying time after last coat: approx. 12 hours


During work substrate and membrane should hold the same temperature. Protect membrane from heat or draught.
Thicknesses exceeding 2 mm may cause crack formations.


Tools should be cleaned with water before the membrane dries up.
Once set, 1K Sealing membrane can be removed mechanically

August 2019

Alfix CeraFill 10 colour Universal grout has been improved, and its name is now being changed to UniversalFuge - CeraFill 10.


Read moreSee the archive here


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