External wall insulation (EWI) is a powerful solution to enhance your home’s energy efficiency, reduce heat loss, and improve overall comfort. If you have solid walls and are looking to upgrade your home, understanding EWI is essential. This blog will be a handy guide to help go over a few key points about the EWI process.

What Is External Wall Insulation?

External wall insulation refers to a layer of insulation that’s fixed to the outside of an existing wall. This layer is then finished either with a coat of render or an alternative cladding material to protect it from the elements. EWI is primarily installed on properties  with solid walls, giving them an aesthetic upgrade as well as drastically improving the thermal performance of the walls, leading to lower heating costs for residents within.

A normal EWI system usually consists of:

  • Insulation boarding which is mechanically or adhesively fixed to the wall
  • An initial render coat covering the insulation boarding known as the basecoat
  • A further layer of basecoat along with mesh to ensure stability
  • A top coat and finish which can be in a wide range of colours and appearances (in some cases you may be limited due to planning requirements in your area)

Advantages of External Wall Insulation

  • Reduced Heating Costs

    Up to 45% of the heat from your home can be lost through the walls. By having a continuous insulation layer around your home your heat is kept where it should be – inside! This ensures you spend less time running your heating and can enjoy lower energy bills.

  • Improved Comfort

    EWI not only improves the comfort of your home by helping ensure a consistent temperature can be maintained, but also by following the PAS2035 standard we ensure that sufficient ventilation has been installed alongside the insulation. Not only does this help to prevent any risks from moisture and condensation, but it keeps your home a in a comfortable and healthy state of airflow.

  • Practical Benefits

    Unlike alternative measures for solid walls such as internal insulation, you don’t have to give up any of your floor space! On top of this EWI systems provide your external walls with improved weatherproofing as well as some improvement to sound resistance. This can lead to a longer lifespan of your walls and reputable installers will always provide you with both manufacturers and insurance backed warranties for up to 25 years which can be transferred to new owners if your property is sold.

  • Reduced Condensation Risk

    By properly insulating your home and installing the correct ventilation this can help to eliminate the risk of damp, mould and condensation within your home.

Installation Process: Basic Steps

  • Surveying and Quotation

    Evaluate the property to identify the size of the walls, the condition and any elements that may need to be removed during the process such as: Cables, alarm boxes, lights

    Identifying any remedial work that needs to be carried out prior to the EWI being installed

    Once the quote is generated, accepted, and any remedial works carried out: Installation can begin.

  • Pipework Adjustment and Window Protection

    All pipework will be modified or removed and temporary downpipes will be set up to prevent water damage. All windows will be covered during installation to prevent damage occurring

  • Starter Track Insulation

    Fit a starter track at the base of the wall, this allows for the site team to begin the secure fixing process of insulation boarding.

  • Insulation Board Placement

    The panels are then attached using either adhesive mortar or mechanical fixings. A full envelope of the building will be completed and all fixings will be based on clear manufacturers guidance.

  • Render and Meshes

    Once all insulation boards have been fixed and checked, an initial basecoat of render is applied. After this has dried a second coat of render is applied along with mesh to reinforce the work. This coat is then left to dry before moving on.

  • Top Coating

    At the end of the project a final “top-coat” is added which gives the intended appearance and weatherproofing coat. Once dry your EWI system is fully installed and completed.

Common Materials Used

  • Expanded Polystyrene (EPS)

    A commonly used product that provides cost effective thermal performance and lightweight rigid insulation boarding. For a deeper dive into EPS insulation we’d recommend checking out this blog provided by EWI Store which contains a detailed breakdown of what it is and the benefits of the material.

  • Mineral Fibre

    Due to its vapour permeability, mineral fibre insulation is often specified for projects on specific buildings to ensure condensation risk is minimised while also providing excellent thermal efficiency.

Remember, professional installation is crucial for optimal results. Always ensure you are using a trusted installer that is PAS2030 and Trustmark registered to get high quality works that will protect your home. As a fully registered and certified installer we know the importance of getting the work done right and supporting the whole journey for our customers.

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