EWI-251 Insulating Render Coat is designed to create high-performance, thermal-insulating and vapour-permeable coatings for external applications. It offers an alternative to traditional external insulation systems, helping to improve energy efficiency while allowing the building fabric to breathe. It also provides acoustic benefits, helping to reduce external noise and improve overall comfort. Designed for use as an insulating undercoat within an external render build-up, it should be finished with EWI-252 Repair Render for a smooth, sponged finish, or with EWI-075 Silicone Render for a more contemporary appearance.

Intended Uses

EWI-251 Insulating Render Coat is intended for external use as a breathable, insulating render coat on suitable wall substrates. It is suitable for blockwork, masonry, stone, concrete and refurbished wall surfaces where an insulating render layer is required. For non-standard backgrounds or applications, advice should be sought from the EWI Pro Technical Team.

Why Choose EWI-251 Insulating Render Coat?

• Helps improve energy efficiency with a thermal-insulating render layer
• Vapour-permeable formulation helps the wall build-up breathe
• Offers acoustic benefits that can help reduce external noise
• Suitable for blockwork, masonry, stone, concrete and refurbished walls
• Can be used as an alternative to traditional external insulation systems
• Suitable as an insulating undercoat within an external render build-up
• Compatible with EWI-252 Repair Render or EWI-075 Silicone Render as finishing options

Substrate Preparation

Before application, the substrate should be assessed for condition, moisture and, where relevant, salinity. Substrates must be clean, sound and free from dust, soot, grease, release agents, paint residues and excess mortar. Any weak, damaged or friable areas must be removed and repaired, and any fungal or mildew growth should be treated and removed. Highly absorbent substrates should be lightly pre-dampened with clean water before application. Dense or low-suction surfaces may require priming to promote adhesion.

Product Preparation

Mix with approximately 14 litres of clean, cool water per 30L unit using a suitable mechanical mixer until a homogeneous consistency is achieved.

• Mechanical mixing should take around 2 to 3 minutes
• When mixing by hand, mix for approximately 4 to 5 minutes
• Do not remix hardened material

Application

Apply EWI-251 Insulating Render Coat evenly using a hawk and trowel or suitable spray machine. It can be applied in total thicknesses from 20mm to 120mm, with each individual layer applied at a maximum of 30mm. Level with a straight-edge tool and leave the surface open. Do not smooth, float or rub. Additional layers may be applied once the previous coat has set sufficiently.

Application Conditions

Application should be carried out in ambient, substrate and material temperatures between +5°C and +25°C. Protect the surface from frost, rainfall, excessive temperatures, strong winds and rapid drying during application and curing.

Technical Data