What is External Wall Insulation (EWI)?

Did you know – solid wall buildings lose twice as much heat as those with cavity walls?

External Wall Insulation (or EWI) – sometimes also referred to as Solid Wall Insulation – is a layer of exterior insulation material, which is glued and mechanically fixed to the exterior of a property and then covered in a number of coats of render. The insulation material acts as a ‘thermal barrier’ to improve the energy efficiency characteristics of the building, and the render acts to protect the property and the insulation from the elements.

ewiModern EWI systems have a number of unique features that mean that installing EWI on a property can have a significant number of benefits to you and to the building. Insulation material is now ‘breathable’, which means that damp and condensation will not build up inside the property, but that heat will be retained. Renders now contain a silicon component which make them slightly flexible, which will ensure that the exterior walls of the building do not develop unsightly cracks or allow water ingress. In addition, all exterior finishes that RenderRight use are:

  • Anti-crack – silicone-based renders provide a strong finish that will age well
  • Self-cleaning – the structure of the render prevents dirt and dust building up
  • Colour-preserving – render will not fade or change colour over time
  • Available in a whole variety of different textures and finishes
  • Available in over 500 different colours

Our team only use the highest-quality products on all jobs. Our business thrives on recommendations from satisfied customers, and so it’s well worth our investment in suitable materials and training programmes to continue to receive such positive feedback. Attention to detail is a key component of every job we do, and we (or our suppliers) will never sign-off until the end customer is completely satisfied.

How will External Wall Insulation benefit me?

Adding EWI to your property and then rendering it has a number of benefits, some obvious and some not so obvious. We think these can be neatly summarised as:

  • The property uses up to 50% less energy, meaning that the work will pay for itself
  • The value of the property will increase by up to 15%
  • The inside of the building will be warmer and more comfortable
  • The ‘look and feel’ of the property, and the local environment, is improved
  • The property will stay looking good for far longer
  • EWI prevents damp and condensation building up inside
  • EWI improves weather proofing and reduces noise internally
  • All our systems can be applied without any disruption to the household
  • The floor area of the home remains the same (not the case for internal insulation)

How is External Wall Insulation installed?

A typical EWI install is completed in a number of stages.

EWI Installation Process

External Wall Insulation

First, scaffolding is put up around the areas of the property that are going to be treated. This sits further away from the external walls than it would for other types of building work.

The exterior of the property is then treated and any gaps in brickwork are filled. If the property has been rendered previously, this render is usually removed in order to ensure that the insulation board can be securely fixed to the building.

All doors, window frames and any other important exterior features are then covered with plastic masking material to protect them.

Next, a series of rails and mechanical fixings are added to the outside of the building to securely hold the insulation in place. The insulation board is then cut and affixed to the property with adhesive and a number of different types of fixing. The fixings are then tightly clamped into the insulation and any holes filled to ensure a completely flat surface is achieved when the building is rendered.

We then seek the closest series of dry days (approximately 3 in a row) in order to begin rendering the property. A number of mesh products are used to ensure the render correctly adheres to the building. Then a base coat of breathable render is applied. This is followed by one or more top coats. Time is left in between each coat to ensure it dries thoroughly.

The top coat render is in the colour and texture finish that the customer chooses. A number of firms spray this on, but we always use traditional application techniques (as a skilled plasterer would) to ensure a dead flat, level surface.

Next, all details are taken care of and windows and doors are uncovered. Window cills will be extended where necessary, aerials, satellite dishes and other fixtures such as exterior lighting are put back up, and then all edges (e.g., window and door frames) are sealed with a colour-matched mastic – or a contrasting one should the customer desire.

Scaffolding is then taken down and the site is jet-washed completely to ensure it’s as clean, or even cleaner, than it was before the work started.

Finally, an official handover process is undertaken with the customer. This is done in line with the PAS 2030 standard that RenderRight are certified to, and ensures that the customer is completely satisfied and that they’re in possession of all necessary documentation, such as product information sheets. The work is logged with our insurance-backed guarantee provider and the guarantee will arrive with the customer within 14 days of completion of the install.

Are there any drawbacks?

There are very few drawbacks to installing EWI, and any are vastly outweighed by the number of distinct benefits above. The only that we know of are that exterior fixtures need to be fixed to the property using special fittings that won’t damage the EWI system, and that care must be taken to protect the EWI system when exterior features of the property are changed. In addition, planning permission must sometimes be sought to install external wall insulation on your property, although our experts are on-hand to assist you in this process and to date we haven’t had any rejected planning applications.

EWI fixing

EWI fixings

All other potential issues have now been rectified by suppliers and system manufacturers. RenderRight can supply its customers with the fittings they need to use – for example, to put up hanging baskets. We can also come and do these jobs for you. Modern insulation materials are becoming thinner whilst also more thermally efficient, and most systems now allow windows and doors to be replaced at some point in the future without any damage to the EWI.

Please feel free to contact us if you have any other questions.

How long does EWI take to install?

The process outlined above usually takes approximately 1 week for a small property (e.g., 2-3 bedrooms) and around 2 weeks for a larger building. The work will be undertaken by a team of 2 to 4 specialist operatives working together – again, this is dependent on the size of the property. We always aim to finish in as short an amount of time as possible, but not to the detriment of our work. Unlike other firms, we will not ‘cut corners’ and may sometimes request that we wait 1-2 days for a suitable “weather window”, which is especially important when exterior render is applied.

How much does External Wall Insulation cost?

This is often dependent on a number of factors – in particular the size of the property, the number of walls that need to be insulated and rendered, and the ease of access for scaffolding. In order to give you an accurate quotation, we will need to visit your property to assess and measure it. We will always provide a detailed breakdown of costs in our quotation. Please fill out this form to request a free, no-obligation quote.

Help is available with the cost of installing EWI currently. The government’s Green Deal and ECO schemes provide assistance to customers looking to upgrade the energy performance of their property. Given that EWI is an energy-saving measure with significant impact, it is likely that between 50 and 80% of the cost of the install can be funded, and up to 100% in certain cases or if a Green Deal plan is taken out.

RenderRight are an approved Green Deal Installer for both Internal Wall Insulation and External Wall Insulation. Please contact us to find out more.