EWI-221 Rapid Set EPS Basecoat is a fast-setting, polymer-modified cementitious adhesive designed for time-critical external wall insulation and render-only applications. Supplied as a dry mix in 25kg bags, it offers dual functionality as both an adhesive for fixing EPS insulation boards and a reinforced basecoat prior to render finishes. Its accelerated setting time helps keep projects moving, while still delivering a compact, durable and waterproof finish. It is a strong choice for installers working to tight programmes or in cooler conditions where reliable progress on site matters.

Why Choose EWI-221 Rapid Set EPS Basecoat?

• Fast-setting formula helps improve programme turnaround on site
• Dual-purpose product for fixing EPS boards and forming the reinforced basecoat layer
• Designed for time-critical projects where efficiency and reliability are important
• Produces a compact, durable and waterproof finish
• Suitable for EPS insulation systems and render-only applications
• Performs reliably in cooler conditions, with application possible down to 0°C
• Suitable for embedding fibreglass mesh within the basecoat layer

Intended Uses

EWI-221 Rapid Set EPS Basecoat is intended for use in EPS insulation systems and suitable render-only applications where a fast-setting adhesive and basecoat is required. It can be used to fix EPS insulation boards to suitable substrates and also as a reinforced basecoat layer prior to render finishes, with fibreglass mesh embedded within the material. Much like EWI-220 EPS Basecoat Adhesive, it offers dual functionality, but with the added benefit of accelerated setting times for projects where speed on site is particularly important.

It is suitable for EPS insulation boards only and is not suitable for fixing XPS insulation boards or for application onto bituminous substrates.

Substrate Preparation

Substrates must be sound, stable, clean, dry and free from dust, grease, loose material or any contamination that may affect adhesion. Uneven surfaces should be levelled before application. Absorbent mineral substrates should be primed with EWI-301 Water-Based Primer, while smooth or painted surfaces should be checked for soundness and prepared with EWI-310 Universal Primer where required. When used as a basecoat, insulation boards must be securely fixed, level and flush before application.

Product Preparation

EWI-221 Rapid Set EPS Basecoat is supplied as a dry mix and must be mixed with clean water before use.

• Mix with approximately 5.3 litres of clean water per 25kg bag
• Mix thoroughly with a mechanical paddle mixer
• Continue until a smooth, lump-free consistency is achieved
• Do not add further water once the product has begun to set

Application

When used as an adhesive, apply the material to the back of the EPS insulation board using a suitable trowel. For uneven substrates, apply a perimeter ribbon with dabs through the centre of the board. On flatter substrates, the adhesive may be applied over the full surface using a notched trowel. Fix boards firmly to the substrate and allow the adhesive to set before mechanical fixing.

When used as a reinforced basecoat, apply the material evenly over the installed EPS boards and embed alkali-resistant fibreglass mesh while wet. Apply additional material as required to fully cover the mesh and achieve a smooth, even surface ready for finishing. Protect freshly applied material from adverse weather conditions during application and for at least 8 hours afterwards.

Application Conditions

Do not apply in rain, high humidity or where wet weather is expected before the product has set. Do not apply if the substrate or materials are frozen, or if the temperature is below 0°C or likely to fall below 0°C during setting. Protect the work with suitable coverings where necessary.

Technical Data