External wall insulation cost per m2 in Ireland

Materials only, and why that still matters

Ask three contractors for an external wall insulation price and you will get three different numbers, and most of the gap is not labour, it is the spec. Board thickness, adhesive type and which render finish is chosen all move the materials cost per square metre before a tradesperson is even booked. We cannot quote your job here without seeing the elevations, but we can show you exactly what a square metre of wall costs in materials, built up layer by layer from real prices, so a quote makes sense when it lands rather than feeling like a number pulled from the air.

What goes into one square metre of wall

A standard EWI build-up is board, adhesive and basecoat, reinforcing mesh, primer, then a render finish. Taking 100mm Graphite EPS External Wall Insulation Board as the base case:

Layer	Product	Covers	Cost per m2
Insulation board	Graphite EPS 100mm, EUR 43.00/board	3 m2 per board	EUR 14.33
Adhesive and basecoat	Ceresit ZU 2-in-1 EPS Adhesive & Basecoat 25kg, EUR 20.99/bag	4 m2 per bag	EUR 5.25
Reinforcing mesh	Fibreglass Reinforcing Mesh 160g, 50m2 roll, EUR 69.99/roll	50 m2 per roll	EUR 1.40
Primer	Ceresit CT16 Render Primer 15kg, EUR 40.99/tub	30 m2 per tub	EUR 1.37
Silicone render finish	Ceresit CT74 Silicone Render 1.5mm 25kg, EUR 72.99/bag	9 m2 per bag	EUR 8.11
Total, these five layers			EUR 30.46

That EUR 30.46 is the core system cost per square metre of flat, uninterrupted wall with a 100mm board and the standard CT74 silicone finish. It does not include fixings, corner and window beads, or the labour to put any of it up, which is covered below.

Board thickness changes this figure the most

The insulation board is the single biggest line item, and it is also the one figure most likely to move once a BER assessor or SEAI grant spec tells you what thickness you actually need. All our Graphite EPS boards are the same price per board, EUR 43.00, but a thicker board covers less area per board, so the cost per square metre rises with thickness:

Board thickness	m2 per board	Board cost per m2
20mm	15	EUR 2.87
50mm	6	EUR 7.17
100mm	3	EUR 14.33
150mm	2	EUR 21.50

Going from 100mm to 150mm adds roughly EUR 7.17 per square metre on the board alone, on top of whatever the extra thickness does to window reveal depth, cill extensions and the length of fixings you need. We cover how to choose the right thickness for your wall and U-value target in a separate post, but the cost table above is the number to plug into that decision once you know the thickness you are aiming for.

Silicone render: a small line item that still moves the total

Render finish is a smaller share of the total than the board, but it is not fixed. Ceresit CT76 Silicone Render 1.5mm 25kg is the higher-build option at EUR 78.99 a bag against EUR 72.99 for CT74, which works out at roughly EUR 8.78 per square metre against EUR 8.11, a difference of under a euro a square metre. Swapping render grade is not where the big savings or costs are, so choose based on finish and durability rather than trying to shave this figure down.

What this figure leaves out

This EUR 30.46 per square metre (100mm board, CT74 finish) covers the flat field of the wall only. It does not include:

• Fixings - Polystyrene Insulation Fixings are priced per 100 and the quantity needed depends on wall height and wind exposure, not a flat rate per square metre, so we price these once we have your elevations.
• Corner, stop and window beads - these are priced per linear metre of perimeter and opening, not per square metre of wall area, and the quantity depends entirely on how many windows, doors and corners the building has.
• Labour, scaffolding or access equipment, and VAT.

Add these and you get a true job cost, but they scale with the shape of the building rather than its area, which is why a materials list from actual elevations gives a far more accurate number than any per-square-metre rule of thumb, including the one above.

Send us your wall areas and we will cost it properly

Send us the wall area in square metres, the board thickness you are working to, and roughly how many window and door openings there are, and we will put together a full materials list and cost, fixings and beads included, not just the flat-wall figure above. In-stock orders go out within 7 working days, insulation boards are quoted individually since volumes vary job to job, and delivery is free in Ballincollig and Cork City. Collection is by appointment only, so give us a shout first.

Call 085 868 8459 or email sales@all4building.ie and we will get you an exact figure.