External Wall Insulation & Insulated Render Systems

Whilst Structherm are renown for their unique Structural External Wall Insulation System we recognise that such a system may be over engineered for many projects. Often, a standard EWI system may be all that is required.

There are millions of solid wall and non-traditional properties in the UK which suffer from poor thermal performance. If these are structurally sound and the substrate of sufficient quality then a direct EWI system may be all that is required.

How do you know if standard EWI is fit for purpose? Simple – just give our technical team a call. We’ll take a look at your project, test the substrate and give you our honest opinion.

This is why Structherm also offer a full range of standard EWI systems. Systems which incorporate a variety of insulants which can be topped with a wide array of different renders, brick effects, textures, finishes and colours.

Why EWI?

Usually, the most significant heat loss from any property is through the external walls. This is estimated to be around 35% of the total heat loss. This results in high fuel consumption and therefore high CO2 emissions. The Government’s target is to make an 80% reduction in these emissions by 2050. External Wall Insulation systems can play an important role in achieving this.

External Wall Insulation EWI System

EWI involves externally cladding a building with insulation boards, before applying a layer of basecoat render and then a final decorative finish. The overall result is not only a highly insulated, energy efficient home. It’s also one that is visually transformed on the outside.

Structherm’s comprehensive range of External Wall Insulation and Insulated Render (IR) systems are fully BBA approved. They provide a high degree of thermal efficiency, vapour permeability, impact resistance and large choice of textured finishes and colours.

Benefits of External Wall Insulation

  • Significantly improved thermal performance.
  • Reduced fuel consumption and therefore less COemissions.
  • Impact resistance of 6N/m.
  • The systems are classified as class 0 or ‘low risk’ as described in the national Building Regulations. They have also attained BS 8414 part 1 (fire performance of external cladding systems).
  • Improved acoustic performance. Transmission of external airborne noise through the external wall is much reduced.
  • No risk of condensation as dew point occurs on the outside of the system.
  • Due to external application, residents are able to stay in their homes with minimal disruption to their lives.
  • Prolongs building life.
  • Low maintenance.
  • Wide range of finishes and colours.
External Wall Insulation EWI

System Characteristics & Options

Structherm’s External Wall Insulation Systems are made up of several layers, which provide the thermal performance and aesthetic qualities required when refurbishing a building. For the first layer, choose from our range of high performance insulation panels. Theses can be enhanced EPS, mineral fibre or phenolic foam to meet your thermal requirements. The middle layers are then a combination of base-coat and mesh which give the system strength and impact resistance. To complete the system choose any finish from our contemporary or traditional ranges. Opposite is a photograph showing the typical build up of the Structherm “Thin Coat” system with an Acrylic finish.


  • Refurbishment of local authority and housing association properties: Low rise or high rise.
  • New build or solid wall properties.
  • Schools, colleges and universities.
  • Commercial & office premises.


  • Social Housing: Low and high rise.
  • Private Housing: New build and refurbishment.
  • Education: Schools, colleges and universities.
  • Commercial: Office buildings etc.
  • Private Landlords: Housing.
  • Park Homes.

Quality Assurance

Our External Wall Insulation systems carry a full warranty. They are BBA approved with a minimum 30 year design life, and are fully patented.

Every project has an individual quality assurance procedure, supported by:

  • BS EN ISO 9001:2015
  • Professional indemnity insurance
  • Product guarantee insurance
  • A close working partnership with Approved Installation Contractors

Insulation Specification

Insulation type and thickness is specified on a project by project basis. It is based on thermal performance and measured in U-Values.

All construction materials such as brick, insulation, plasterboard and render have a Lambda value. This is a measure of how they conduct heat. Used together during the construction of buildings, various materials will determine the overall thermal performance of a wall. This is known as the U-value. The lower the U-value, the more thermally efficient the wall construction is.

A U-value calculation will take into consideration the wall thickness and material and any render or insulation used. In a typical Victorian property with 9 inch solid brick walls the U-value is 2.08 W/m2K.

Our range of high performing insulants, which are available in varying thicknesses, ensure that our systems dramatically improve thermal performance. They can achieve or exceed current Building Regulation u-values.

EWI Installation Procedures

Systems must be applied to a substrate that is structurally sound. Once the type and condition of substrate is known, the correct choice of proprietary fixing can be determined. This is done by fixing pull out tests undertaken prior to work proceeding.

Structherm Standard EWI Systems

Thin Coat - Low Rise: NSC2

This system incorporates several different types of rigid insulation board. Onto these a thin build up of high polymer modified basecoat render is applied. A glass fibre reinforcing mesh is then embedded within. The system is then ready to receive a variety of decorative finishes. From traditional renders to dash finishes to brick slips / effects. All finishes are available in a wide array of colours, textures and effects.

BrochureBBA Certs., Finishes / Colours.

Thin Coat - High Rise: NSC2

The build up of the high polymer modified basecoat render incorporating a reinforcing mesh onto rigid insulation boards is similar to that of the low rise system. When it comes to buildings over 18m (11m in Scotland) however the understandably strict fire regulations dictate the use of Mineral Fibre insulation only along with fire rated fixings. Again, a full variety of finishes, textures and colours are available.

Brochure, BBA Certs. Finishes / Colours.

Heavy Duty - Low Rise: NSC3-5

The heavy duty systems add superior strength and improved impact resistance. Hence these are ideally suited for low rise applications. The system incorporates a thicker build up of polymer modified render. A steel mesh is then through fixed to provide a more robust system. The system can them be finished off with a dash receiver and aggregate, a variety of render finishes or brick slips / brick effects.

BrochureBBA Certs.Finishes / Colours.

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