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External Wall Insulation FAQ (EWI)

Improving your home can be a daunting consideration. Here are some of the most Frequently Asked Questions we hear at Energy Saving Grants regarding EWI

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EWI Testimonials

My house is now warm and comfortable for the first time since moving here 18 months ago. I recommend them to anybody looking to save money on their energy bills and make their house more energy efficient.
Audra Reid

Energy Saving Grants arranged for me to get help towards the cost of having my house insulated. My house is now so much warmer and looks a lot better too! I would definitely recommend them to anyone.

Holly Hackett

Thank you very much indeed for providing me with the grant funding for the External Wall Insulation for my house. My house is so much warmer and is the envy of my neighbours. I have passed your details to my neighbours and I think the whole street will be wanting it done.

Mr. Price, Swansea

External Wall Insulation FAQ

Do I need Planning Permission?

Planning Permission is not normally required for External Wall Insulation. However, if you live in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty, or in a listed building, then Planning consent will be required.

Is External Wall Insulation suitable for any property?

External Wall Insulation suits a wide range of properties, both existing and new-build.


How long has External Wall Insulation been used for?

Although EWI has only really become popular in the UK within the last deacde (since the building regs were amended in 2010), it has been installed on properties in this country since the 1970s. However, in large parts of continental Europe, EWI has been used extensively since the 1950s. Therefore EWI is a tried and tested energy saving measure.


Is it correct that I need to insulate my walls if I am re-rendering my house?

Building Regulations (Part L1B) sets energy efficiency requirements where more than 50% of an external wall (or more than 25% of the overall building envelope is being renovated).

This means that whatever renovation you are undertaking to your wall, if it affects more than half the wall (or more than a quarter of the overall building envelope) you will need to add insulation to improve the thermal performance of the whole of that individual thermal element.

How thick will my External Wall Insulation be?

The most popular thickness is 100mm (4 inches) which is comprised of 90mm of insulation board and 10mm of basecoat and render. However, insulation boards vary from 20mm to over 150mm, so the choice is yours.


What decorative finishes are available?

A wide choice of styles are available including a vast choice of colours, textures, pebbledash as well as real and simulated brick effect and timber effect finishes.


How long will the External Wall Insulation take to install?

External Wall Insulation on average takes about 2-3 weeks from assembly to dismantling of the scaffolding. As with most external building works the installation is weather dependent.


How will the system be installed?

The system will be installed in a number of key stages. All the external fittings will be removed or redirected, the insulation panels will be applied with a mechanical fixing, followed by the applications of a render system to provide protection and a decorative finish. Upon completion, all external fittings are then repositioned.

Will technicians need to come into my house?

In order to comply with health and safety regulations, technicians will need to enter your property to carry out pre and post installation checks. These include assessing whether or not your home has adequate ventilation in place to prevent carbon monoxide poisoning and mould growth. They will not, however, need to come in to your home to use your electricity, as they will have their own generators. They will also not need to enter to use your water, but may however need to use your outside tap for mixing renders and cleaning up.


Will my TV reception be affected during the installation?

Any satellite dishes or TV aerials fitted to the walls will be affixed to the scaffolding for the duration of the installation.


Can External Wall Insulation be installed when it is raining?

Some activities involved in the installation of external wall insulation are weather dependent and can delay the installation:

  • Very cold weather – anything below 5°C may mean that render cannot by applied as it is too cold for the render to set.

  • Very warm weather – could stop the top render coat from being applied as the silicone top coat can become too tacky to be applied smoothly. This is most likely to happen at temperatures over 25°C and on walls that are in direct sunlight.

  • Wet weather – the render top coat requires at least four hours to ‘set’. If rain is forecast during this time the installers may not be able to finish the property until they get a clear day to work on the property.

Is External wall insulation easy to maintain?

External wall insulation is generally maintenance free. The exterior finishes are designed so they do not allow the growth of mould. Maintenance should be limited to the need to wash down occasionally to maintain an “as-new” appearance


What about fixing news things to my walls, e.g. a hanging basket?

You will need to use fixings that penetrate through the external wall insulation and into the substrate of the building, i.e. the original wall to support heavy items such as hanging baskets.


What if my wall gets damaged after installation?

Your external wall insulation system will withstand typical knocks and bumps. In the event that it is damaged by a very hard impact, repairs can be easily completed, such as with a normal wall.


What is the life span of the system?

All systems are tested by the BBA and NSAI for life expectancy and achieve a rating in excess of 30 years. EWI that was installed in Germany during the 1950s is still in situ today.


Will it add value to my property?

Yes, EWI does not reduce the floor area of your home; it will renew and improve the appearance of outer walls, improves weatherproofing and sound resistance and increases the life of your walls by protecting the brickwork. EWI will also increase the Energy Performance Certificate (EPC) rating of your property, which you are legally required to provide to a prospective buyer. The lower heating bills and increased comfort of an insulated property will also be appreciated by any potential home buyers.

What is a U-value?

A U-value is a measure of how much heat is transferred through a given material; the lower the U-value, the better the insulator it is.

Installing 90mm of external wall insulation on to a typical 225mm thick solid brick wall can reduce the U-value from around 2.70 W/m2K to around 0.29 W/m2K – which is better than most new-build properties!

Check Your Eligibility Using Our Grant Checker

Please ensure that all information provided below is 100% accurate. Any errors in your personal information could delay or prevent you qualifying for a government funded grant.

Please note that you do not necessarily need to be in receipt of tax credits or benefits as we still may be able to obtain funding for you via your Council or through other funding schemes.

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