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 Silicon Finish

Johnstone's Stormshield Dash Finish

Johnstone’s Stormshield Dash Finish

Johnstone's Stormshield Brick Effect Render

Johnstone’s Stormshield Brick Effect Render

Johnstones_ Stormshield

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.

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.

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.

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.

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.

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.

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.

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.

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 BeforeExternal Wall Insulation Glannant Road After

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

Llwyn Onn BeforeLlwyn Onn After

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

EWI Dyffryn Street BeforeEWI Dyffryn Street After

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

EWI Mid ProcessAfter External Wall Insulation

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