External Wall Insulation in Ireland: EPS vs Mineral Wool

With Irish energy prices where they are, external wall insulation (EWI) is one of the best upgrades you can make to an older home. It wraps your house in a warm coat, removes cold bridging and can transform a tired facade at the same time.

The two main systems

Graphite EPS (expanded polystyrene)

Graphite EPS boards are the most popular choice in Ireland. The graphite additive improves thermal performance by up to 20% compared to white EPS, so you can achieve the same U-value with a thinner board.

Pros:

• Best price per m² of insulation value
• Light and easy to cut and fix
• Available in thicknesses from 20mm to 100mm and beyond
• Ideal for most cavity and solid wall homes

Cons:

• Less breathable than mineral wool
• Not suitable where high fire ratings are required (e.g. some apartment buildings)

Browse our EPS insulation system range - panels, adhesives, fixings, mesh and renders all in one place.

Mineral wool

Mineral wool boards cost more but are vapour-open and non-combustible - the right choice for older solid-wall houses that need to breathe, and for buildings with stricter fire requirements.

Pros:

• Excellent breathability - moisture can escape the wall
• A1 fire rating
• Great acoustic insulation

Cons:

• Heavier and more expensive than EPS
• Needs careful handling in wet weather during installation

See our wool insulation system products.

What makes up a full EWI system?

Whatever board you choose, a complete system needs:

1. Starting track - keeps the first row level and protects the bottom edge
2. Adhesive - a 2-in-1 adhesive like Ceresit ZU bonds the boards and embeds the mesh
3. Insulation boards - e.g. Graphite EPS 100mm
4. Mechanical fixings - polystyrene anchors, around 6-8 per m²
5. Fiberglass mesh - reinforces the base coat
6. Corner and window beads - crisp, crack-free edges
7. Primer + finish render - a silicone render like Ceresit CT74 stays cleaner for longer in Irish rain

What thickness do I need?

For a typical solid wall, 100mm graphite EPS brings the U-value to around 0.27 W/m²K - the level required for SEAI grant support. Cavity walls that already have some insulation may only need 50-80mm.

SEAI grants

Homeowners can claim up to €8,000 (detached house) towards external wall insulation through SEAI. The work must be done by a registered contractor, but sourcing materials smartly still keeps the overall project cost down.

Need help estimating materials?

Send us your wall areas and we will put together a full system quote - boards, adhesive, mesh, beads, fixings and render. Call us on 021 487 6963, message us on WhatsApp or email sales@all4building.ie. We deliver nationwide from our Ballincollig warehouse.