Tag Archives: solid wall insulation

Can I Install External Wall Insulation on a Cavity Wall?

At EWI Store, we receive many enquiries from homeowners who are very interested in installing EWI. However, there is often confusion as to whether it is possible to install EWI on a home with existing cavity wall insulation. In today’s post, we’re going to be tackling this question to see if we can clear things up!

What is Cavity Wall Insulation?

If your home was built after the 1920s, it’s likely that it will have been built with a cavity between the two exterior walls.

The main purpose of this cavity was to prevent damp crossing over from the outside through to the interior walls, but it wasn’t until later that people realised it could be used for another purpose. Nowadays, cavity walls are often retrofitted with an insulation material in order to increase energy efficiency and reduce the amount of heat lost through the walls.

In today’s housing stock, cavity wall insulation (CWI) seems to be the default method of wall insulation however, this isn’t to say that there haven’t been people with negative experiences of it. Damp and condensation have often been reported as a side effect of CWI, usually occurring as a result of cold bridges caused by poor installation. There are therefore many people who are quite rightly wary of CWI, so they instead look elsewhere for their wall insulation solutions.

What is External Wall Insulation?

If your home was built before the 1920s, then it’s likely to be a solid wall property. These properties present a bit of a challenge in terms of increasing energy efficiency because there is no cavity to fill, so homeowners either have to opt for no insulation (and high energy bills), internal wall insulation (IWI) or external wall insulation (EWI).

EWI provides the best solution for this type of building, as it is fitted onto the outside walls by securing the insulation boards with adhesive and fixings. A protective render is then applied to the insulation boards to create a weatherproof seal.

Unlike IWI where the thickness of the insulation is severely limited by how much floor space you can give up, EWI allows users to install insulation as thick as 200mm onto the outside walls of their properties.

Further to this, the effectiveness of CWI is dictated by the amount of insulation that can actually fit within the cavity – some cavities are just 50mm wide, so the benefits of insulating this are pretty slim.

EWI, therefore, offers increased potential for homes to massively up their efficiency. Unfortunately, it’s commonly assumed that homes with cavity wall insulation are: a) insulated well enough, and b) cannot have EWI as well as CWI.

To see what materials you will need and how much EWI may cost, visit our Materials Calculator Tool.

Can I have both EWI and CWI?

In fact, if you have CWI, then EWI is likely to reduce any problems with damp caused by the cavity wall insulation. This is because EWI completely envelopes your home in a weather-proof blanket, preventing water from entering through the exterior walls and keeping the temperature of the walls nice and warm. Because EWI wraps around the entirety of the exterior walls, there are no gaps and therefore thermal bridging is kept to a minimum.

So, because the internal temperature of the walls increases, the chances of damp and interstitial condensation are reduced. If there were any cold spots within the cavity wall insulation before, then the EWI will counteract the effect of these by maintaining a warm wall temperature.

If you currently live in a cavity insulated house and you want to upgrade the wall insulation even further, get in touch! We can talk you through the process and offer you our technical expertise.


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Is External Wall Insulation Soundproofing?

Noise pollution can be incredibly frustrating. Whether it’s from road traffic, railway networks, aircraft or just plain old noisy neighbours, measures can be taken to increase the soundproofing capabilities of your home.

External wall insulation (EWI) is excellent for soundproofing. Not only does EWI improve the thermal performance of your property, but certain types of insulation can also dramatically improve the acoustics of a building. We’re going to be talking a bit about the negative impact of noise pollution on human health, and which external wall insulation system is best for preventing this.

What are the effects of noise pollution?

Noise pollution has proven to significantly affect children, adults and the elderly. According to research carried out by Rockwool, noise pollution can cause stress and fatigue due to disturbed sleep patterns. In turn, this can lead to health problems and a slower rate of development for children.

The Best Insulation for Soundproofing

If you live in a solid wall property, it’s unlikely that your home will be adequately soundproofed. This is because, generally, homes are built with insulation in the walls (cavity wall insulation) that absorbs the sound and protects the house against noise pollution. EWI is a great choice if you live in a solid wall property, or even if your property just needs an extra soundproofing boost.

Mineral Wool insulation is the best one to go for if soundproofing is a concern. Renowned for having excellent insulating capabilities, the insulation not only reduces the amount of noise entering your home but is also all the more effective due to the fact that it is installed externally. The entire insulation system seamlessly envelopes the house and is, therefore, a highly effective solution against sound pollution. We recommend using the Mineral Wool insulation at a thickness greater than 200mm.

Of course, with a Mineral Wool external wall insulation system, it’s not just the soundproofing capabilities that you reap the rewards of. Mineral Wool has excellent thermal insulating capabilities, is class A1 fire rated (the highest standard!) and is also very breathable. So, overall, this is a very healthy insulation material for buildings!

How is the insulation installed?

If you are new to the idea of EWI, it’s very simple!

  • The Mineral Wool is doubly secured to the external wall using both our Premium Basecoat adhesive and metal pin mechanical fixings.
  • Once the boards are secured to the wall, the Premium Basecoat is again applied on top and fibreglass mesh is embedded within the basecoat for extra crack resistance and tensile strength.
  • Once the basecoat is dry, a render primer is painted on and left to dry.
  • After this, a thin coat render is applied on top of the basecoat to create a decorative finish.
  • The overall result is a higher performance building in many respects, and an aesthetically pleasing, brand new finish!

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The Lloyds Bank British Business Excellence Awards

We did it! EWI Store has been shortlisted as a finalist in The Lloyds Bank British Business Excellence Awards in the category Small-To-Medium-Sized Business of the Year. This award celebrates resilience and innovation within some of the UK’s best businesses and we are so proud to have been shortlisted for this prestigious award!

What is The Lloyds Bank British Business Excellence Awards?

Attracting a variety of organisations, from small startups to large corporations, the Lloyds Bank British Business Excellence Awards is the largest and most comprehensive business awards programme in the UK. These awards acknowledge businesses that find new ways to support their communities and where employees thrive in times of hardship. This prestigious award is only awarded to businesses that are able to demonstrate clear processes aimed at supporting their local communities.

What Have We Achieved This Year?

Many have struggled over the past year and, to further support our community of homeowners, installers and architects, we have invested heavily in our training. This training is aimed at both new and experienced installers who are looking to either gain the necessary skills for the industry or to maintain their professional development and keep up to date with the latest processes and techniques. This year, we created an educational CPD (Continual Professional Development) programme aimed at architects which we have successfully had approved by the Royal Institute of British Architects (RIBA). This shows that our CPD course is of high quality and meets the very stringent criteria that are required to gain RIBA approval.

Here at EWI Store, we handpick only the highest quality products to sell in our stores. We stock the full range of products from EWI Pro who are well known for their supreme range of silicone renders. Their Premium Bio Silicone Render is an award-winning render, resistant to cracking, biological growth and discolouration and thereby providing a stand-out finish for years to come. By selecting only the best products, we ensure long-lasting and high-quality results for our community.

As usual, we would like to thank all our customers for their continued support. Make sure to keep your eyes peeled for future announcements!

Is External Wall Insulation Expensive?

Many of us here in the UK are interested in the idea of External Wall Insulation, with a vast range of benefits both environmental and financial it is easy to understand why. The biggest reservation many people have is regarding the upfront cost of the External Wall Insulation installation process. In today’s blog, I will explain the costs and hopefully put your financial worries to rest!


The process of External Wall Insulation has many components; the price accounts for the required insulation materials and labour costs. The cost of EWI materials will depend on the size of the project but also what EWI materials you choose. Not only do the prices of materials vary, but some materials require fixings and some require adhesive which will also need to be accounted for within the price. This means that the cost of your EWI system will depend entirely on the specific needs of your project.


Calculating the cost of the External Wall Insulation Materials

As explained above, there are a lot of components to consider when calculating the price. Luckily, we have a great solution for you; not only do we have a fantastic team on hand who can provide you with a quote, but we also have an easy-to-use EWI Materials Calculator tool that takes all of the faffs out of the calculation process. If you would rather have a helping hand and some guidance, just give us a call on 02033974067.


What is the EWI Materials Calculator?

The EWI Materials Calculator is an online tool that enables homeowners, installers and architects to quickly and accurately calculate the correct EWI materials needed to meet their requirements for their next project. The calculator will ask a series of questions to gather how much the system will cost depending on your needs.

Average External Wall Insulation costs:

EWI Typical Cost
Mid-terrace house £4,000 – £6,000
Semi-detached house £8,000 – £10,000
Detached house £12,000 – £14,000 +


This may seem like a scary amount for some but if your property has solid walls, you could save between £115 and £360 a year by installing External Wall Insulation. This means, over time, the External Wall Insulation will start to pay for itself. You have to remember that not only will you save on your heating costs, but you will also reduce the amount of CO2 emissions your property emits into the atmosphere which will help the environment. Your External Wall Insulation job will also be finished with your choice of render and colour, providing additional value if your brickwork is damaged, worn down and in need of a makeover.

If this still sounds like too much for you, there is government-backed support that you could be eligible for. Currently, there is a subsidy called the Energy Company Obligation (ECO) which was launched in December of 2018. The scheme runs until the 31st March 2022 and focuses on customers with low incomes and considered to be in vulnerable situations e.g. living in fuel poverty. Under ECO, grants are available to cover all or part of the cost of energy efficiency measures. Ask your energy provider for more information on this scheme.

Trade Installers get fantastic prices and warranties on the system

As an installer, you may well be eligible for our trade discount prices too; so, not only will you get a BBA-approved external wall insulation system delivered directly to the site, but also the materials you need at a great price. As a trade partner, we are also able to offer system warranties provided the installers have been on our free training course. Be sure to sign up to our Trade Account for free to receive your discounts!

So, there you have it – if you need some help calculating the material requirements for an EWI job, give us a call or use our EWI Materials Calculator today!


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