Izonil Lightweight & Waterproof Screed provides a totally waterproof barrier without the need for a membrane and is guaranteed waterproof for 15 years. It is also environmentally friendly too because it does not contain any bitumen, resin derivatives or toxic ingredients. 


This high quality, expanded clay and cement, fibre reinforced, dry mortar is impervious to water and meets the requirements of BS EN 13318 CT-C16-F4.  Specially developed for levelling and waterproofing floors and flat roofs, it is manufactured to strictly controlled specifications. It is supplied pre-bagged and requires only the addition of water on site.

  • Waterproof
  • Lightweight
  • Fibre reinforced for increased tensile strength
  • Resistant to direct water contact
  • Good thermal insulation properties 
  • Good sound absorber
  • Fire resistant
  • Freeze/thaw resistant
  • 15 year guarantee

Izonil screed is designed for levelling and waterproofing floors and flat roofs. It solves problems caused by rising damp, water penetration or moisture in many applications, for example: cellar/basement floors, showers, wet-rooms, swimming pools, spas, green roofs, terraces, patios and balconies. It is also suitable for sound and fire proofing new or existing timber or loft floors. 

Preparing the Surface
The base concrete surface should be structurally sound and free from
excessive dust, laitance, dirt and contaminants such as oil and grease. To properly clean the surface, the whole area should be brushed over
with a stiff bristle broom and water.

Before applying the screed, ideally the base should be thoroughly wetted down with a cement grout (generally a slurry of cement and water) to optimise cohesion between the screed and the concrete base.

When using on timber floors or on any hygroscopic surface, a vapour control layer must be laid down before applying Izonil screed. This is critical to avoid any moisture loss during setting which may reduce the final strength and quality of the screed.

Izonil screed is ready-to-use, just add water (5 to 6 litres to 25kg of screed).  Mixing time is approximately five minutes if using a continuous mixer.

Working time is 1 to 3 hours, depending on ambient conditions. 

Do not add anything else to the mix. Hardened screed should not be remixed or reused.

Applying Izonil Waterproof Screed

Izonil screed is not self-levelling. Application may be undertaken by hand or with screed pumps using conventional tools for laying sand and cement screeds. 

During application the surface and air temperature should be between 5 and 25°C.

Minimum thicknesses vary from 30 to 75mm depending on performance requirements. See our technical information sheet.

Access by light foot traffic is normally possible within 24 to 48 hours and complete drying time is 28 days.

Curing & Post application treatment

It is essential that completed areas be prevented from drying too quickly, especially when used externally, for example on roofs. Additionally, the screed must be protected from rainfall - covering with plastic sheeting or similar, to good site practice, at normal temperatures between 5 and 25°C.

Note that Izonil screed is not designed to be a wearing surface and once hardened should be tiled, painted with concrete paint, carpeted or finished with hardwood flooring.

When used in conjunction with under floor heating systems pipes should be laid over the screed to increase efficiency and take advantage of the natural heat reflecting thermal benefits of the material.


Tools and equipment should be cleaned with water. Hardened Izonil screed can only be removed mechanically.

Tools and equipment should be cleaned with water. Hardened Izonil screed can only be removed mechanically.


Izonil Lightweight & Waterproof Screed is supplied in 25kg paper bags 


Approximately 10kg of screed will cover 1m² at 10mm thick layer, excluding allowances for wastage, surface profile and porosity. One 25kg bag laid at the minimum thickness of 30mm will cover 0.8m². 


Izonil Lightweight & Waterproof Screed may be stored for up to 12 months if kept in original, unopened bags on wooden grids and protected from moisture and frost.