EWI-225 Premium Basecoat – 25kg

5.00 out of 5 based on 4 customer ratings
(4 customer reviews)
£18.14 (incl VAT)

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EWI-225 Premium Basecoat is our strongest and most flexible basecoat adhesive. It is used in render-only systems as a basecoat – the Premium Basecoat eliminates the need for priming prior to skim-coating with render, reducing time and costs. In external wall insulation systems, the Premium Basecoat can also be used to attach Mineral Wool boards to the wall.

  • High strength
  • Dual-purpose
  • Breathable
  • Waterproof
  • Frost-resistant
  • High elasticity

About EWI-225 Premium Basecoat

EWI-225 Premium Basecoat is our finest basecoat adhesive – it is used to fix mineral wool insulation boards to substrates in addition to being used within the basecoat layer. The adhesive is white due to the presence of white Portland cement – making it stronger than other basecoat adhesives (EWI-220 and EWI-210). Once the basecoat has dried it provides and incredibly strong and flexible basecoat layer and as such we recommend using the basecoat when applying ‘render only’ systems to substrates

The EWI-225 Premium Basecoat is breathable, high strength and waterproof.

EWI-225 Premium Basecoat can be used for two purposes:

  • An adhesive used to create the reinforcement basecoat layer in render only or mineral wool EWI systems
  • An adhesive used to fix mineral wool (Rockwool) to a substrate.

EWI-225 is prepared in the same way regardless of whether it is being used as a basecoat adhesive or to fix the mineral wool insulation boards to the substrate.


The Premium Basecoat comes as a dry mix in 25kg, so needs to be mixed with clean, cold water ( >5.9 litres) prior to use. We suggest using a large bucket and adding the water prior to the Premium Basecoat dry mix. Once our Premium Basecoat has been added to the water, it needs to be mixed using a paddle mix until an even consistency mortar is produced.

Once the Premium Basecoat has been mixed sufficiently, leave the bucket for 5-10 minutes and then remix using the paddle mix – the adhesive is then ready for use.

If using the Premium Basecoat for the basecoat layer, apply the basecoat using a 10mm notched trowel to the substrate. Then embed overlapping pieces of fibreglass mesh – the mesh should sit within the middle of the basecoat layer. Once embedded the basecoat layer should be 6mm in total.

If using the Premium Basecoat to fix Mineral Wool to the substrate, the basecoat can either be applied to the whole surface of the insulation board using a notched trowel or applied to the perimeter of the insulation board + 3 dabs across the middle.

Application Conditions:

  • Primer: EWI-301 or EWI-310 if a key is required
  • Application temperature (air, substrate, materials): from +5°C to 25°C
  • Time of usability after mixing with water: approx. 2 hours (temp. +20°C)
  • Water mix proportions: approx. >5.9 litres of water per 25 kg of dry mix
  • Quantity to be used:
  • – fixing insulation panels of foamed polystyrene and reinforced layer on foamed polystyrene: approx. 4-5 kg/m2
  • – fixing insulation panels of mineral wool and reinforced layer on Mineral Wool: approx. 5-6 kg/m2

Coverage Rates 

1 x 25kg bag – 4-5m2

Technical Specifications 

  • Composition: white Portland cement, mineral fillers, synthetic fibres, polymers, modifying admixtures
  • Bulk density: approx. 1.60 g/cm3
  • Adhesion to concrete (air-dry): ≥ 0.3 MPa
  • Adhesion to concrete (after freeze-thaw cycles): ≥ 0.3 MPa
  • Adhesion to foamed polystyrene (air-dry): ≥ 0.08 MPa (foamed polystyrene rupture)
  • Adhesion to foamed polystyrene (after freeze-thaw cycles): ≥ 0.08 MPa (foamed polystyrene rupture)
  • Adhesion to Mineral Wool: 0.08 MPa (Mineral Wool rupture)


Do not dispose of Premium Basecoat along with household rubbish. Ensure that Premium Basecoat packaging is clean and empty before disposal. Leftover product should be not be allowed to reach sewage or watercourse systems.

Safety Measures

  • Wear protective clothing during use.
  • Avoid contact with eyes.
  • Avoid contact with skin for extended periods of time.
  • Always ensure that water and/or washing facilities are available on site.


Comes in powder form in a 25kg paper bag.

Storage Conditions 

Store in a cool, dry place. Avoid ingress of water. Shelf life: up to 12 months from the date of manufacture.


SKU: EWI-225
Weight25 kg

4 reviews for EWI-225 Premium Basecoat – 25kg

5.00 out of 5
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  1. Rated 5 out of 5

    F Baumann

    Has to be the best adhesive, comparable to the StoArmat Novo or the StoArmat Levell basecoats. Trust me, I have installed Sto, Baumit and other German systems.

    A 25kg bag can typically do 5 to 6 metres for us of the basecoat layer. You can mix it according to instructions but we tend to use our own judgement through experience. The powder is cream and when mixed with water comes nicely when applied with the trowel.

    It can be used for mineral wool and eps, but I just use it on eps systems all the time, but I dont waste the ewi-225 for sticking boards, I tend to use the ewi-220.

  2. Rated 5 out of 5

    Simon Grade

    Great gear this. 6-8mm on top of insulation boards with mesh and render goes on great too.

  3. Rated 5 out of 5


    Use the premium adhesive on our last job. It is great. would recommend. It is very strong, mixes well and goes on easy.

  4. Rated 5 out of 5


    Good as a basecoat for silicone render systems, gives a durable result.

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