Home Insulation Costs in Ireland: EWI, Attic, and Cavity Wall Guide (2026)
Residential Insulation Guide for Irish Homeowners
Upgrading your home’s insulation is the most effective way to eliminate drafts, cut heating bills, and boost your property's Building Energy Rating (BER). However, with multiple insulation methods—such as External Wall Insulation (EWI), drylining, and cavity wall injection—and a massive array of materials like PIR boards, Rockwool, and insulation rolls, choosing the right solution can be overwhelming. In this guide, we break down current pricing, material options, and efficiency benefits for 2026.
Home Insulation Cost Breakdown
The cost of insulating a house in Ireland depends heavily on the insulation method chosen. Here is a baseline of typical installation costs (before SEAI grant deductions):
- Attic/Loft Insulation: €1,200 to €2,800 (depending on roof size and insulation depth).
- Cavity Wall Insulation: €1,000 to €2,200 (pumped bead method for cavity walls).
- Internal Drylining (Insulated Plasterboards): €4,500 to €11,000 (average 3-bed semi-detached).
- External Wall Insulation (EWI): €8,000 to €18,000 (solid walls wrapped with exterior EPS boards).
Choosing the Best Insulation Materials
Different areas of your home require different insulation materials to achieve optimal thermal performance (R-value) and meet current Irish building regulations:
- Rigid PIR Insulation Board (e.g., Kingspan, Quinntherm): PIR (Polyisocyanurate) insulation boards are the industry standard for internal drylining, floor insulation, and pitched roof rafters. They offer extremely high thermal performance at a minimal thickness, making them ideal when space is at a premium.
- Rockwool Insulation (Stone Wool): Stone wool slabs are excellent for acoustic dampening and fire resistance. They are widely used for insulating intermediate floors, internal partition walls, and timber frame structures.
- Glasswool/Mineral Wool Insulation Roll: Economical, flexible insulation rolls (like Knauf Earthwool) are the standard choice for attic floor joists. To meet the target U-value required by the SEAI, a minimum depth of 300mm of mineral wool rolls is recommended.
The Crucial Details: Floor and Edge Insulation
While wall insulation gets the most attention, heat loss through floors (especially concrete slabs) accounts for up to 15% of energy loss in older homes. Installing high-density floor insulation boards beneath underfloor heating pipes is critical. Additionally, when EWI wraps your external walls, ensure window cill projections are properly managed to prevent cold bridging. Upgrading to custom aluminium window cills from specialized local suppliers like CILLS LTD (cills.ie) protects your brickwork borders from water run-off and ensures a clean finish.