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How to calculate the cost of an External Wall Insulation system

Calculating the cost of an external wall insulation (EWI) system is not as simple a task as you might think; the price not only accounts for the insulation materials but also the installation of the system, labour costs, square meterage (for example, our reinforcement mesh comes in 50m rolls while a bag of EWI-220 Adhesive will cover 3m2 of the wall), the choice of decorative finish and so on. What’s more, not only do the prices of materials vary, but some materials require fixings and some adhesive which will also be included in the price. Therefore, the cost of your EWI system depends entirely on the needs of your project. So, how does one go about calculating the cost of their EWI system?

Calculating the cost of the External Wall Insulation Materials

At EWI Store, we have just the solution for you. Not only do we have an excellent team on hand who will be happy to provide a quote – simply give them a call with some rough measurements of the area that needs to be insulated, and they can quickly calculate the EWI materials you need using their expertise – but we also have a fantastic tool available at your fingertips…

The EWI Materials Calculator

Whether you have experience with external wall insulation, or you’re keen to have a go, you can use our accurate, easy-to-use EWI materials calculator!


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.

The questions the EWI Materials Calculator will ask are as follows:

Information needed to calculate the cost of External Wall Insulation

So, at this point you might be wondering what information the materials calculator will need in order to generate a system quote. We will outline each of these below!

Firstly, questions will vary depending on what you are interested in: eco, premium, or standard. This relates to the decorative finish you want on your walls.

  •  Amount of metres squared needed

To calculate the number of metres squared needed, multiply the width by the height of each wall you are going to insulate. Do not subtract windows or doors; this will give you an incorrect result as our calculator considers wastage in the final calculation.

  • Corner Bead with Drip and Mesh (3mm)

    £5.02 Excl. VAT
  • PVC Stop Bead – Mesh (10mm)

    £3.97 Excl. VAT
  • Starter Track 170mm-240mm (2m)

    £29.26 Excl. VAT

So, you might be a homeowner looking to install external wall insulation or apply a fresh new render façade to your home. Or a solid wall insulation installer looking for an easy-to-install product (at a great price), or even an architect looking for a way to vastly improve the thermal efficiency of an old property. Whatever the reason, you have come to the right place and can be assured that the materials calculator will assist!

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!


13 thoughts on “How to calculate the cost of an External Wall Insulation system

  1. Should you leave cavity wall insulation in place if we want to add external wall insulation or remove it? Will the cavity carry cold draughts?

    1. Hi Susan, if the cavity wall insulation is in place and it is not causing any issues, I would add the EWI on top. If there are any issues with the cavity wall insulation (damp in the house) then remove it!

  2. I’ve had a couple of quotes from companies for the install. Do you know how much they should be putting on top for the pipework?

    1. Hi Ameria, it depends completely on how much pipe work there is I’m afraid. But anything from £200 up to well over £1000 depending on quantity and the materials used.

  3. Hi James, We are looking at getting solid wall insulation, and we are interested in buying the materials to do so from yourselves, but we are finding it hard to find an installer who operates in this manner. It seems all solid wall insulation installers want to offer the full package (materials and install), would you be able to recommend one? I have been recommended this type of insulation by a friend of mine who had it done a couple of years ago. She said it has made a tremendous difference to her home and they hardly need the heating on at the moment so I think it is something we will end up doing to our home. Your thoughts would be appreciated!

  4. We are looking to insulate our house but we need to remove the pebble dash, is there a cost per m2, so we can giv e ourselves a rough idea of the cost before we start any of the works.

  5. This is extremely useful. We were looking at insulating our end terrace property and had an EPC carried out. The EPC recommends solid wall insulation but puts the price between £4,000 and £12,000 which simply isn’t useful. It is interesting to know that most installers calculate prices based on the square meterage of the wall. We hope to get our insulation in March when the weather improves a little. Thanks for your help.

    1. No problem Raymond. We have talked to DECC (and now BEIS) about this in the past. It is very difficult, because there is a such a massive variation in costs. I think to be honest if you try and use £100 per m2 as a rule of thumb you should provide yourself with a much more accurate quote. In terms of the materials, you are looking at about £25 per m2, scaffolding £10 per m2 and the rest is then down to the install cost. Installers costs vary considerably, but always get quotes and we don’t recommend always going for the cheapest quote. Solid wall insulation is difficult if you don’t know what you are doing – we have trained hundreds of installers over the years and the quality of the finish they can achieve really does vary greatly. When render is applied nicely to a building it can look like a million dollars and bearing in mind it is one of the first thing that people see when they turn up to your home, it is not something we would skimp on. Always go with recommendations from friends and family, or give us a call and we can normally recommend local installers. The GreenAge also offer a great installer map which has local approved installers – access this by clicking here.

    1. Hi Emily,
      Please can you let us know where you are based and we can send through some recommended external wall insulation installers.

  6. If you are using this product over SIPS do you require a vapour barrier between the SIPs and the insulation

  7. I own a Victorian 3 storey, solid brick, end of terrace house which I rent out. I cannot change the appearance of the front but the sidewall is perfectly flat with no windows, pipes etc. It seems to me that a first step to improving the insulation would be to put external insulation on this wall. The wall is 9.5m long and approx 8m high. Please could you tell me what the most cost effective solution would be eg what material I should specify and what the overall cost per sq m should be.

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