External wall insulation cost per m²: what goes into each metre
External wall insulation — what quotes in Spain call SATE (Sistema de Aislamiento Térmico por el Exterior, known in the standards as ETICS) — is quoted per square metre, but not everything it involves is measured that way: the edges of the facade and the outline of each window go by the linear metre, and the scaffold, the permit and the rubble are separate. Here is what makes up that price, what drives it and what a quote should make clear so that two offers can be compared. What you will not find is a figure per metre given without seeing your facade.
What external wall insulation is and why it goes on the outside is covered on the page about the system.
The same square metres, two different prices
With the same surface area, the facade with more windows has less wall and much more work around the openings: lining reveals and lintels, reinforcing the mesh at the corners of each opening and dealing with the junction with the window frame and the sill. That is why a well-prepared quote for external insulation separates the square metres from the linear metres.
When a quote gives a single price per square metre “with detailing included”, that price contains an estimate of how much detailing your facade has. It is not necessarily wrong, but it cannot be compared with another unless you know how many metres of detailing each one has assumed.
The same 60 m² of facade
Less wall area, and more than twice the detailing
Few openings
- Wall area
- 55.02 m²
- Around openings
- 14.8 m
- Base, top edge and corners
- 31 m
Many openings
- Wall area
- 49.26 m²
- Around openings
- 34 m
- Base, top edge and corners
- 31 m
- Wall area, in m²
- Detailing around openings, in metres
- Facade edges, in metres
Two facades of 10 × 6 m, with windows of 1.2 × 1.2 m and a door of 1 × 2.1 m. These are example measurements and the figures are geometry, not prices.
Four decisions that change the price of each metre
Once the metres have been counted, the price of each one depends on four things. None of them can be fixed over the phone, and all four should be visible in the quote.
The insulation and its thicknessWhich material, and how many centimetres
Systems are offered with different insulation materials — expanded polystyrene (EPS), white or with graphite, extruded polystyrene, mineral wool — and each has its own price per centimetre. The thickness is not picked from a catalogue: it is calculated for the building. And the thicker it is, the more the material costs and the deeper the window sills and the returns around each opening turn out.
The finishRender or pieces
For a render, a primer and the finishing mortar on top of the reinforced base coat are enough. With ceramic, stone or brick, the base coat takes double mesh or fixing anchors, and on top go the adhesive, the pieces and the grout. Two different renders differ almost only in the material; a render and a finish in pieces are two different jobs.
The wall underneathWhat has to be done before anything is bonded
The insulation is bonded to the facade, so the facade has to be able to hold it: anything loose is hacked off, anything hollow is made good, anything that is not flat is levelled and, if there is damp, that is dealt with first. It is what varies most between two houses with the same square metres, and the only thing that sometimes cannot be fully known until the work starts.
Access equipment and timeMany passes over the same wall
External insulation is not one coat and then another: it is boards, anchors, base coat with mesh, primer, finish and detailing, each with its drying time. That means many more days with the scaffold up than for a paint job, and the days of scaffold, sheeting and occupying the street all count in the price.
The finish options, one by one, are in external wall insulation finishes. And which access equipment suits each facade, with what you pay for each one, is in what it costs to paint a facade, option by option.
An external wall insulation quote, line by line
This is how to read one that is worth having, without amounts: line by line, with the unit for each item and what it should make clear so that you know what you are paying for.
Quote · External thermal insulation
| Item | Unit | What to look for |
|---|---|---|
| 01Access equipment: scaffold, sheeting and protection | Lump sum | What equipment is used, who puts it up and takes it down, how many days it is costed for and who applies for the permit to occupy the street. |
| 02Surface preparation | m² | What it includes — cleaning, hacking off loose material, levelling — and at what rate anything that turns up is charged. |
| 03Starter profile | Linear metres | At what height the system starts and how the plinth is dealt with. |
| 04Insulation | m² | Material, thickness and system name, with its European Technical Assessment. |
| 05Fixing: adhesive and anchors | m² | That it includes both, and how many anchors per square metre. |
| 06Base coat with mesh | m² | Whether the ground floor has reinforcing mesh on top of the standard one. |
| 07Corners and openings | Linear metres | Corner profiles, mesh reinforcement, returns on reveals and lintels, and the junction with the window frames. |
| 08Finish | m² | Which render or which piece, the texture and the colour, with its light reflectance value. |
| 09Window sills and top edge | Linear metres | Whether they are replaced or extended, and in what material. |
| 10Downpipes, grilles and units | Per item | What is taken down and refitted away from the wall. |
| 11Licence, fees and waste | Lump sum | Who handles the council permit and who pays the fees and the removal of rubble. |
IVA, with the materials in view
Under the route for home renovation work, the IVA law (IVA is Spanish VAT) only applies the 10% rate if, among other conditions, the materials supplied by whoever does the work do not exceed 40% of the taxable base. In external insulation, materials weigh much more than in a paint job, so the quote should say which rate applies and why.
Whatever turns up when hacking off
At what unit rate any repairs that could not be seen are charged, per square metre or per linear metre, written down before work starts. Whatever is decided by eye with the scaffold up always works out dearer than what would have been agreed in advance.
The permit, with a name on it
Work that changes the facade goes through the town hall, and when the scaffold stands on the public highway, so does the permit to use it. On top of that, where the municipality has introduced it, there is the construction tax (impuesto de construcciones). Make sure the quote states who handles it and whether it is included in the figure.
The IRPF deduction, as it stands today
For work that improves the energy efficiency of a home, the law on IRPF (Spanish income tax) has a deduction in three forms, and external insulation acts precisely on what they measure. This is what the text in force says, as read in the BOE (Spain’s Official State Gazette) on 7 October 2026.
20%
Your main home, or one you let or are going to let as a home
If heating and cooling demand falls by at least 7%.
Work carried out and paid for by 31 December 2026
Maximum base: 5,000 € a year
40%
The same homes
If non-renewable primary energy consumption falls by at least 30%, or the home reaches an A or B rating.
Work carried out and paid for by 31 December 2026
Maximum base: 7,500 € a year
60%
Owners of homes in a predominantly residential building
If the building’s non-renewable primary energy consumption falls by at least 30%, or the building reaches an A or B rating.
Work carried out and paid for by 31 December 2027
Maximum base: 5,000 € a year and 15,000 € in total
In all three, the improvement is demonstrated with two energy performance certificates issued by a qualified technician: one from before the work starts and one from after. The first two cannot be combined for the same work, and they do not cover garages, storerooms, gardens or swimming pools; none of them covers any part of the home used for a business activity.
A word of honest warning: this deduction has been extended by royal decree-law (real decreto-ley), and more than once the Spanish Parliament (the Congreso) repealed the extension by not ratifying it, and it had to be approved again. Before counting on it, check with your tax adviser or with the Agencia Tributaria (the Spanish tax agency).
What to bear in mind before asking for a price for external wall insulation
The “before” certificate, before you start
If you are going to claim the deduction, the first energy performance certificate has to be issued before the work: the improvement is measured against it, and one issued once the work has started is no use. Commission it from a qualified technician when you ask for quotes, not when you accept one.
The same system in both quotes
External insulation is assessed as a whole, as a system, and the data sheets of the systems we have read cite their European Technical Assessment. Compare the same insulation, the same thickness and the same finish: if one quote changes any of the three, you are no longer comparing the same job.
Price per metre — which metre?
Wall area or facade area; with openings deducted or measured straight across; with the detailing included or on its own line. Until you have those three answers, two prices per square metre from two different firms do not say the same thing, however similar they look.
What people ask about the cost of external wall insulation
How much does external wall insulation cost per square metre?
How much does external wall insulation cost per square metre?
We do not give a figure without seeing the facade, for the reasons this page explains: the square metre is only one of the units in the quote, and it is driven by the insulation and its thickness, the finish, how much detailing your facade has, how it can be reached and the condition of the wall. With photos of every side, their measurements and which way each one faces, we will send you a fixed, itemised quote.
Is it more expensive than painting the facade?
Is it more expensive than painting the facade?
Yes, and the two cannot simply be compared. Painting treats the surface that is there; with external insulation a multi-layer system is added to it, with its detailing, and the finish is only the last layer. What they share is the access equipment: if the facade was going to be painted anyway, the scaffold is put up and paid for only once.
Is the IVA (VAT) on external wall insulation 10%?
Is the IVA (VAT) on external wall insulation 10%?
It can be, if the work is on a home, it is commissioned by a private individual or the comunidad de propietarios (the community of owners), the building was completed more than two years ago and the other conditions in the law are met. With external insulation, the one to check closely is the materials condition: what the firm supplies cannot exceed 40% of the taxable base.
Are there grants for external wall insulation?
Are there grants for external wall insulation?
As well as the IRPF deduction we explain above, there are public energy-renovation programmes that open and close through calls for applications, each with its own requirements. Check what is open when you are going to do the work and, before taking anything off the quote, wait until it has been awarded.
Can it be done in phases?
Can it be done in phases?
It can, but each phase pays again for putting up the access equipment and for the paperwork, and between the insulated part and the part that is not yet insulated there is an edge that has to be finished off so that water does not get in. If it is done that way, each phase should start and end at a corner or a change of plane.
How much will I save on my electricity bill?
How much will I save on my electricity bill?
It depends on the house, which way each facade faces and how you use it, and we are not going to give you a made-up percentage. The figure that counts is the one that comes from comparing the energy certificate from before with the one from after, which is also the one the deduction requires.
Ask for your insulation quote, itemised
Send us photos of each side, the approximate measurements and how many storeys it has. We will send you back a quote with the square metres separated from the linear metres, the system named and each item on its own line.