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How can I insulate my external walls?

Why should I consider external wall insulation?

Perhaps you have installed cavity wall insulation but are looking for a more significant impact, or maybe you live in a solid-walled property.

However, as EWI Store, we recommend external wall insulation for several crucial reasons:

  • To save energy and therefore save more money on bills
  • Improves the external appearance of a house
  • Enhances the acoustics within your home – soundproofing
  • It takes up no internal floor space- more room
  • Also, it keeps the property warmer in the winter and cooler in the summer (many people report that their houses stay so warm that they hardly need to turn the heating on)
  • Prevents dampness and also condensation
  • Prolongs the life of your building – protects against extremes of weather conditions
  • Can increase the value of your property in terms of external appearance and Energy Performance Certificate Rating
  • Low maintenance and long-lasting

A quick run through of the main stages of installation:

Firstly, the wall is prepared to ensure the insulation system will stick for the external wall insulation enactment. It should be possible to install our insulation system on the existing render or pebbledash. But, at this point, a substrate check will need to be done. You should then prime the surface. After, you need to set the surface for 24 hours. A starter track is attached to the wall above the damp proof course to support the insulation boards. Then, connected with adhesive and double-fixed with mechanical fixings. Used to reinforce the system, fibreglass mesh enhances the system. Also, the wall is rendered and a topcoat is applied. Moreover, the external wall insulation put into minimising cold bridging and maximising efficiency.

Can I choose the materials?

All the steps work together to create an effective, attractive and long-lasting system. Also, the external wall insulation is a customisable system. The householder can choose between four insulation materials: Kingspan K5, mineral wool, expanded polystyrene (EPS) or extruded polystyrene (XPS) boards.

Firstly, mineral wool is durable, breathable and highly fire retardant. Polystyrene insulation is cheap and a fantastic insulator. Therefore, a thinner layer can be added to achieve the same results as a more considerable amount of mineral wool. There is also a choice of render, tailored to different environments, and options for the final colour and texture of the walls.

How much does external wall insulation cost?

Please fill out our materials calculator to find out more about the approximate costs of materials. You can also give us a call, and we can put you in touch with one of our approved installers who will be able to carry out the work for you to the highest standard. All our installers have full training, and we offer a free aftercare service for customers.

Check out our video with TheGreenAge, all about installing external wall insulation!



11 thoughts on “How can I insulate my external walls?

  1. I need to render my old property anyway, so it makes sense to do insulate the house at the same time I guess, my question is can you change windows out after you have installed this system?

    1. Hi DaveOmell, we would always recommend changing the windows before carrying out the rest of the solid wall insulation works, mainly because if you do it at this stage, the seal around the windows and the system will be better. Normally if you let the window company know you are planning on carrying out these works they can provide you with windows with pre-extended sills, then the additional depth of the insulation won’t be a problem – the new window sills will still come past the outer edge of the wall.

  2. Hi Gretta, insulating your external walls with our external wall insulation is a great idea to improve the thermal comfort of the home. Your home will definitely stay warmer in the winter, but it actually depends on the depth of the insulation you actually end up going for. On the whole, the thicker the insulation the warmer you will be and the less your heating will need to be on, but also thicker insulation costs a little bit more and also if you go really thick you begin to inhibit light entering the house. We recommend 90mmm if you go for EPS and 120mm if you go for mineral wool insulation. Mineral wool insulation is completely non-combustible, it is made from rock! EPS is flame retardent rather than fire proof, but in the event of a fire, the insulation would melt within its cement enclosure (which is part and parcel of our external wall insulation systems)! They are not to be confused with rainscreen cladding which is a very different product!

    1. Hi Lewis, I suggest attending one of our training days to learn more about the system, however many plasterers do try to do this themselves and they get on fine!

  3. Hi there. We are considering external insulation for the ground floor of our 1920’s bungalow (the roof was recently converted to living space, so is already insulated to a high standard). We have been advised that removing the external pebble dash type render would be risky as it can take brickwork with it. We also think there is no physical damp-proof course, based on chemical treatment completed by previous owners. Are there solutions to these issues that allow your products to be installed without any increase in damp risk?

    1. You can install over pebbledash that’s not a problem. Do a tap test with a hammer and only remove if it sounds hollow. you would normally start the insulation and starter track for the system just above DPC level. If insulating the area below the DPC, or down to ground level, you would use XPS insulation as opposed to the EPS. Hope this helps 🙂

  4. Do you know if I can grow climbing roses up an EWI system – is the silicone render tough enough to resist the thorns? Do you sell wall fixings that go through the EPS to anchor to the wall behind for fixing wires, drainpipes etc?

    1. Hi Amanda, Silicone Render is very durable but we can’t guarantee it wouldn’t be compromised with climbing roses. We do sell SWIFIX fixings which hold multiple accreditations so they’re a fantastically reliable solution for fixing wires and drainpipes; we’ve recently posted a blog about the range of fixings

      Have you got a Silicone Render already installed?

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