External Wall Insulation is the perfect cost effective way to add extra warmth and give your home a brand new look.

What is External Wall Insulation?

External Wall Insulation (or EWI) is applied externally to your building through various insulating and protective layers and finished with an external silicone enhanced acrylic render or dash finish. Uninsulated solid stone or solid brick walls can lose substantial amounts of heat if left untreated.

Johnstone’s Stormshield Silicon Finish

Johnstone’s Stormshield Dash Finish

Johnstone’s Stormshield Brick Effect Render

How do Exterior Wall Insulation systems work?

Rigid grey expanded polystyrene (EPS) insulation boards which are enhanced with graphite for better thermal performance are applied through mechanical fixings to the outside of the property to create a warm blanket to the building. The insulation is then covered with a reinforced fibreglass mesh basecoat followed by a primer and render finish.

The loss of heat through structural imperfections or insufficient insulation can be a serious and very costly problem. Heat energy can be lost from your home in three main ways, radiation, convection and conduction. It is thought that around 35% of the heat loss in your home could be caused by walls that are either badly insulated or have no insulation at all. Air is also lost through roofs without insulation, accounting for 25% of the total heat loss in your home. Most of the common types of insulation materials used work by reducing the flow of convective or conductive heat. Therefore, external wall insulation is crucial for reducing the loss in energy from your home.

7 Reasons for Installing External Wall Insulation

If have been interested in external wall insulation and wondered does external wall insulation add value to your home, in the following post we hope to show that there are various great reasons to investing in it. To be exact, we have highlighted a total of seven reasons why you should buy external wall insulation.

One of the Most Effective Energy Efficiency Measures

Heat travels through your home from the warmer areas to the colder ones until there is no difference in the temperature throughout the property. External wall insulation systems help to both reduce any heat gains during warm weather and heat losses during colder weather. It provides a certain degree of resistance to the flow of heat and acts like a protective barrier for the interior of the property from the weather conditions on the exterior. When you invest in insulation, you will reduce the air leakage considerably and your energy bills could be reduced by half the price.

It Increases the Durability of the Home’s Construction

There are a variety of different insulating finishes and renders that have been designed to specifically provide your home’s external walls with a protective barrier that will last a long time. EWI fills any gaps and cracks in the walls and stops damp providing suitable protection against constant exposure to rain weather and cold. Due to the high quality and durable materials used in external wall insulation, additional protection is provided to the brickwork and the structural integrity of the building.

It Reduces Thermal Bridges

Thermal bridges normally occur in areas of a structural envelope where there is not enough insulation in place. This is then often responsible for around 35% of the increased condensation and thermal losses that can make the building the perfect breeding ground for mould.

It Improves the Thermal Performance and Comfort

As noted earlier in the post, external wall insulation, when properly installed, helps to ensure your property stays cool during the warmer days in the summer and warm in the coldest days of winter. It helps to improve the thermal performance and comfort by reducing the heat lost and drafts through the roof and walls. Therefore, your property will have a more consistent temperature throughout the year.

This will obviously make your home a lot more comfortable and pleasant to live in, regardless of what the weather is like on the other side of the external walls.

It Reduces the Likelihood of Condensation and the Growth of Mould

One of the biggest problems in a property, aside from the loss of heat and an inconsistent temperature throughout your home, is the risk of condensation.

Condensation is the result of differences in temperature between both the internal walls and external walls and windows of the property where warm moist air in your property condenses on cold external surfaces.

When there is too much condensation that is not being dealt with, there is a chance that this can cause mould to grow and spread. Mould growth is closely connected to the humidity levels and air temperature in your property. Therefore, when you increase the insulation your home has, the temperature on the surface of the walls in the building will be much higher than without it, thus reducing the risk of mould forming and then eventually spreading.

The problem of mould is one that should not be underestimated, as it is not only responsible for affecting the aesthetics of your home and the structural integrity, but also affects the quality of the internal air. This can then present health complications, especially if anyone in your household has an allergy to mould.

External wall insulation therefore reduces the likelihood of condensation in the property. It can also help prevent damp wall with its weatherproof coating. You can get top coat silicone renders, for example, that provide a hydrophobic 100% waterproof layer of protection for external wall insulation.

It Improves the Aesthetic Qualities of Your Home

The external appearance of your home can be greatly improved by external wall insulation. There are now a wide variety of different finishes including full silicone renders, enhanced silicone renders, dash renders and brick slip finishes .

Whether your home is an older property or a newer one, or it has a modern or more Victorian design, the external wall insulation you invest can be chosen to match perfectly with the rest of the style of the building, so it does not look out of place.

This is obviously important if you are looking to increase the value of your home, particularly when you are looking to sell it.

It Can Help Reduce the Impact of Your Home on the Environment

Residential buildings in the UK are the cause of 31% of the country’s CO2 emissions.

With that in mind then, it’s worth noting that the reduction of energy consumption from domestic heating can help to lower the CO2 emissions and be part of the fight against climate change. For the UK to reach its net zero 2050 target, we need to reduce heating emissions by 95%.

Hopefully, you can see why external wall insulation is so important. Although we have highlighted seven reasons looking into external solid wall insulation and cavity wall insulation, there are many other good reasons. So, if you are wondering – does external wall insulation add value to your home? – we would have to answer that yes it does.

If you are interested in finding out the external wall insulation cost per m2 or have any other queries or questions, get in contact with LMG Home Improvements today.

Frequently asked questions about external wall insulation

Does external wall insulation help with damp and condensation?admin2026-01-12T13:24:05+00:00

Does external wall insulation help with damp and condensation?

External wall insulation can help reduce condensation and penetrating damp by keeping walls warmer and better protected from the weather. For best results, insulation should be installed alongside proper household ventilation, in line with PAS 2035 retrofit best practice. This may include background trickle ventilation, mechanical extract ventilation in wet rooms such as bathrooms and kitchens (DMEVs), or whole-house systems such as Positive Input Ventilation (PIV). This balanced approach helps control moisture levels, improve indoor air quality, and reduce the risk of mould.

How long does external wall insulation installation take?admin2026-01-12T13:23:45+00:00

How long does external wall insulation installation take?

Most residential installations are completed within two to four weeks, depending on the size and condition of the property. Some stages of render application are weather dependent, and timescales may be adjusted to ensure the best possible finish. Every effort is made to minimise disruption.

Do I need planning permission for external wall insulation?admin2026-01-12T13:23:21+00:00

Do I need planning permission for external wall insulation?

Planning permission is not usually required. However, listed buildings or properties in conservation areas may need approval. This should always be checked before work begins.

Does external wall insulation change the appearance of my home?admin2026-01-12T13:23:00+00:00

Does external wall insulation change the appearance of my home?

Yes. External wall insulation can significantly improve the appearance of your property. With a wide choice of colours and finishes available, it can modernise your home or maintain a traditional look.

What render finishes are available?admin2026-01-12T13:22:34+00:00

What render finishes are available?

We offer a range of finishes including silicone-enhanced render, dash render, and brick slip finishes, or a mix of these finishes. These options allow homeowners to choose a style that suits both modern and traditional properties.

What render systems do you use?admin2026-01-12T13:22:11+00:00

What render systems do you use?

We install render systems from several leading manufacturers. Our preferred system is Johnstone’s Stormshield, chosen for its durability, weather resistance, and high-quality finish, helping to protect your property while delivering long-lasting performance.

Will external wall insulation reduce my energy bills?admin2026-01-12T13:21:52+00:00

Will external wall insulation reduce my energy bills?

Yes. By reducing heat loss through your external walls, insulation helps your home stay warmer for longer. This means your heating system works more efficiently, helping to reduce energy consumption and lower household bills.

What types of properties are suitable for external wall insulation?admin2026-01-12T13:13:41+00:00

What types of properties are suitable for external wall insulation?

External wall insulation is suitable for most property construction types, including solid wall, cavity wall, brick, block, concrete, and many system-built and rendered properties. It can be installed on houses, bungalows, and low-rise residential buildings where the external walls are structurally sound. Final suitability is confirmed following a professional survey.

What is external wall insulation?admin2026-01-12T13:13:20+00:00

What is external wall insulation?

External wall insulation involves fixing an insulating layer to the outside of your property’s walls, which is then finished with a durable render or cladding system. This creates a continuous thermal barrier while also improving the look of your home.

Why should I install external wall insulation?admin2026-01-12T13:12:02+00:00

Why should I install external wall insulation?

External wall insulation helps your home retain heat, reduces energy bills, improves indoor comfort, and protects your property from the elements. It also enhances the appearance of your home and can increase its overall value.

Look at the transformation of these properties!

Move the slider from left to right to see before and after photos.

External Wall Insulation Glannant Road Before

External Wall Insulation Glannant Road After

A tired, poorly insulated stone wall given a Johnstone’s Stormshield Exterior Wall Insulation system, with a silicone render.

Johnstone’s Stormshield Wall Insulation system, with a silicone render.

A mid terraced property benefitting from an External Wall Insulation to the exposed face of poorly insulated brick.

The insulation stage of our exterior system and the finished article.

What our customers say

I engaged LMG to help re-render the front of my property, they arrived on time, finished the job pretty quickly and were clear and upfront about the project throughout. I would definitely recommend them.

★★★★★

Mr Walsh, Newport

Very happy with the external wall insulation work LMG has provided and at a reasonable price too. The boys were very friendly and hard working,reliable and the quality of the work is excellent. I was always kept in the loop. I will definitely be contacting them in the near future for work on the inside. Brilliant company!!

★★★★★

Mr Williams, Caerphilly

Very happy with the work done. Very clean no mess couldn’t fault this company. Recommend LMG Home Improvements to anyone.

★★★★★

Mr Morgan, Bargoed

After 2 weeks cooling off period, the boys were here the following week, had my house hacked off to bare brick, soffit wall ties done, weather boards replaced, facias and soffits and an acrylic honeysuckle render put on. Looks really good, very happy with the price as Carmarthen builders were much more expensive. In total it took them a whole 7 days to complete the job. My neighbours are very impressed with their work. The only downfall was that I had to keep them in bacon and egg sandwiches, coffee and biscuits. 🙂 Would definitely recommend them.

★★★★★

Bev Harris

Recently had some insulation render put on our 2 bed terraced house. After the 2 week cooling off period the chaps were on site & had the job done relatively quickly & for a very competitive price. We’re very happy with our Ardente colour which has set off a mini trend on our street.

I would definitely recommend LMG. We’ve got them back on site in a week to render our extension (which we couldn’t do at the same time due to works on our shed)

★★★★★

Christian Skallion

Want to say a massive thank you to all the guys at LMG Home Improvements! I’m extremely happy with the outcome! The guys on site have been fantastic throughout and a real credit to your company. Will happily recommend to anyone.

★★★★★

Mark Falkingham

LMG provided a good, reliable quotation for the works that was in line with other quotes obtained. The quality of the insulation and rendering work completed is excellent; including the detailing around windows, pipes and roof line.

Communication with LMG was excellent throughout, with regular updates at each stage of the work. The professionalism of the communication was greatly appreciated, long with helpful advice on the technical points of the insulation system.

Highly recommended.

★★★★★

Richard Baker, Swansea

We are very pleased with the finished rendering to the front of our house, so we are planning to have LMG do the back next year.

The workmen were very friendly, easy to talk to and listened to our requirements, telling us what would happen, why and when. We felt they had pride in their work.

★★★★★

Dave Fuller, Cwmbran

Very happy with the work done. Very clean and no mess. Couldn’t fault the company. Recommend LMG Home Improvements to anyone.

★★★★★

David Morgan, Bargoed

martin jones

Arranged for quote. No show, no courtesy call. Would not recommend

Stephen Gimblett

Lmg did a superb job in renovating our old tired house into a modern looking house . Matt and Wayne were excellent to deal with. The work boys are super friendly and helpful. JAMES AND JOHN window Men were superb 👌

Jan Pearson

We have waited a very long time to get our house sorted. After several unsatisfactory visits from other firms and pandemic delays, we found LMG. We are very glad we did. They were very professional from the survey through to the finish. The end result - our house looks like new. We have had so many people comment on how great it looks. I didn't know what to expect, but it exceeded my hopes. Wayne was amazing. His help, support and patience were much appreciated, especially with our 'awkward neighbours'. A potential problem was averted and we are grateful to all at LMG for working this out for us. The boys who did the job (Mac and Jay) were polite and friendly and very accommodating, they worked really well as a team, took pride in their work. So hardworking - a refreshing trait these days, also did some additional small jobs for us. Our neighbours even commented on how hard they had worked. The work they did was to a high standard in every aspect. They, along with Wayne, kept us informed of timescales and any issues that needed to be resolved were done without hesitation. Nothing was too much trouble. As my husband works away it was important for us to have confidence and trust in the team. I was happy to go out and leave them knowing that they would just get on with things. At the end of the job everything was left shipshape and a few very minor issues dealt with immediately. We would have no hesitation in recommending LMG. Thank you to all who worked with us on this project especially Wayne, Mac and Jay.

Anthony Hall

External Wall Insulation,(EWI) with replacement doors and windows, soffit, downpipes and guttering. Had a complete external renovation of our old house. From the initial quote with Matt, then Nicky, right to the finish was great. The results are fantastic.The outside of our home now looks like a new build, thanks to; Wayne, Tom, Kyle, Mike, Lee, Lloyd, Connor, Rob and Ash. We had to wait a long time to get the job started, but well worth the wait. Wayne kept us informed, and was easy to get hold of, and calling the office was refreshingly professional throughout. When they said they would call us back they always did. Would recommend LMG for a great local company, that takes pride in their work. There were small issues, which when questioned were resolved immediately, and I am very particular. Tidy workers, polite, respectful and friendly. The windows and doors were removed and installed incredibly quickly and no issue was a problem that James and his team couldn't solve, overall a great job done. Thank you LMG.

Donald Morgan

The workmen arrived on time each day and completed the job within the timescale agreed. They were polite and cleaned up at the end of each day.

Donna Wadley

We had our cavity wall installation removed and was kept informed every step of the way . The work carried out was extremely professional, done quickly and to the agreed time . Would definitely recommend your services.

A. D.

Cavity Wall Extraction. From the first contact with LMG they understood the problem with our wall and took the time to explain why we had the problem and how it could be solved. Their knowledge and patience in explaining what would happen, gave me the confidence to proceed with them to the extraction of the cavity insulation. The work was carried out professionally and after they had finished they cleared away any debris and even washed down the drive.

David Pugh

Initially I was struggling to get firms to even engage with me about getting External Wall Insulation (EWI) and re-rendering on my property but then luckily I found LMG. The initial survey was performed on the day and time as promised, communication and options about the work were clear and well communicated and all my questions answered. I immediately felt like it was a company I could trust and would get the work done to a high standard. There was a wait for the work to start but that was not an issue - the estimated start date were accurate and communication coming up to the start of the work was good. The team undertaking the work were friendly, polite, good natured and committed to doing a good job. Their work was to a very high standard and always kept me informed of progress, answered any questions myself or the building inspector asked, kept the area clean and were quiet and respectful to neighbours. I chose to get this work done for primarily functional reasons - improved weather resistance, increased insulation - but the visual impact of the work has really impressed me and the finish is excellent. I am very happy with the job and interaction with LMG and I have already recommended them to others.

vivien bowyer

We are an end of terrace house and had the outside insulated. The workmen were efficient, polite and obliging, and cleared up after themselves each day. Nothing was too much trouble for the office and i nagged them with queries before deciding to go with LMG. We can heartily recommend the company.

Giuseppe Sipiano

We had our loft insulated more and from the initial consultation through to the works performed we was very impressed with the quality of work, and also the communication with us. I would highly recommend using them.