Cavity Wall Insulation Cost
Average cavity wall insulation prices in Ireland for 2026, comparing contractor quotes with SEAI grant savings.
Standard cavity wall insulation in Ireland costs between €1,000 and €2,300 before grants. After applying the SEAI cavity insulation grant of €700 to €1,500, the net cost to homeowners ranges from €300 to €800.
Pumped bonded bead is the most common and cost effective cavity upgrade. It is injected into empty cavities from the outside, creating a continuous barrier against heat loss without reducing internal floor space.
Cavity Wall Insulation Cost by House Type
| House Type | Typical Cost (Before Grant) | SEAI Standard Grant | Net Cost (After Grant) |
|---|---|---|---|
| Apartment | €1,000 | €700 | €300 |
| Mid-Terrace House | €1,200 | €800 | €400 |
| Semi-Detached House | €1,700 | €1,200 | €500 |
| Detached House | €2,300 | €1,500 | €800 |
Prices can vary depending on external wall area and cavity width. A wider cavity requires a greater volume of EPS beads, which increases the material component of the quote.
What Drives the Cost of Cavity Wall retrofits?
Understanding the key variables in a contractor's quote helps you evaluate prices fairly.
- Total Wall Area: Pumped bead is priced per square metre of wall surface. Multi storey properties have a larger surface area and require taller access equipment, which increases labor costs.
- Cavity Width: Traditional properties have cavity widths of 50mm to 70mm. Modern new builds or extensions may have cavities of 100mm to 150mm, requiring twice the volume of polystyrene beads.
- Access and Drilling: Properties with difficult access (such as narrow side passages or overhanging roofs) may require specialized scaffolding. Drilling through hard engineering brick or granite finishes also increases drilling times.
- Ventilation Adjustments: Installers must check and keep wall vents clear. Blocking sub floor vents can cause joist rot, so contractors must install vent sleeves to preserve airflow.
Worked Cost Examples (2026 Rates)
Mid-Terrace House
- • Wall Area: 50 m²
- • 60mm cavity width
- • Bonded EPS bead fill
- Quote: €1,200
- SEAI Grant: €800
- Net Cost: €400
Semi-Detached
- • Wall Area: 85 m²
- • 80mm cavity width
- • Vent sleeving included
- Quote: €1,750
- SEAI Grant: €1,200
- Net Cost: €550
Detached House
- • Wall Area: 120 m²
- • 100mm cavity width
- • Complete fill & cleanup
- Quote: €2,400
- SEAI Grant: €1,500
- Net Cost: €900
SEAI Cavity Grant Requirements
To qualify for the SEAI cavity insulation grant in 2026, the property must have been built and occupied before 2011. You must hire an approved contractor on the official SEAI register. You cannot claim the grant for DIY work.