Cavity Wall Insulation
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Counties · checked 29 October 2026

Cavity walls, county by county

SEAI's grant is the same in every county. The walls aren't. We went through SEAI's register of 751,700 BER certificates for homes built before 2011, Census 2022 and Met Éireann's temperature records for each county.

Figures from SEAI's BER register, CSO and Met Éireann on 29 October 2026. How we check

Check my grantCall 087 162 1846
90%of 1,836,728 Irish homes were built before 2011, inside the grant (CSO Census 2022)
4.5%of BERs for those homes record an empty cavity, 28% a part-insulated one (SEAI's BER register)
4.2%hollow block, which can't be pumped (SEAI's BER register)
25%rated E, F or G (SEAI's BER register)

Main wall on BER certificates for homes built before 2011, Ireland

  • Empty cavity 4.5%
  • Cavity, part insulated 28%
  • Filled cavity 16%
  • Hollow block 4.2%
  • Solid stone, brick or concrete 14%
  • Timber frame 6%
  • Other or not recorded 27%
CountyBuilt before 2011Empty cavityPart-insulated cavityHollow blockRated E to GDegree days
Carlow90%4.4%34%3.4%23%1,969
Cavan91%3.3%35%2.6%25%2,159
Clare91%5.9%36%1.1%27%1,843
Cork90%4.7%32%2.2%27%1,755
Donegal92%6.6%42%0.0%25%2,211
Dublin89%3.7%19%7.2%23%1,825
Galway90%5.4%43%0.5%25%1,860
Kerry91%5.7%37%0.3%26%1,673
Kildare86%3.3%22%10.9%16%2,093
Kilkenny92%3.7%29%1.3%26%1,961
Laois90%4.6%37%6.4%24%2,080
Leitrim93%3.2%29%0.6%30%2,102
Limerick91%5.3%33%1.2%24%1,837
Longford90%3.8%33%1.3%26%2,094
Louth89%7.9%27%2.8%23%1,951
Mayo91%6.0%40%0.4%29%2,028
Meath85%3.7%25%11.0%19%2,048
Monaghan90%5.0%29%2.6%26%2,182
Offaly92%5.3%30%3.5%33%2,046
Roscommon92%5.0%35%0.4%33%2,088
Sligo92%3.5%29%1.0%26%2,032
Tipperary93%4.4%29%1.1%34%1,959
Waterford91%4.5%30%1.0%23%1,781
Westmeath92%5.3%26%5.5%25%2,162
Wexford90%3.9%38%1.1%27%1,844
Wicklow88%3.7%20%7.5%25%1,883

Built before 2011: CSO Census 2022, households. Wall types and ratings: SEAI BER Research Tool, the full public file downloaded 29 October 2026: 751,700 certificates for existing homes built before 2011, leaving out the BERs done for grant claims. Empty cavity: a cavity wall with a U-value of 1.0 or more. Degree days: Met Éireann 1991–2020 monthly means at the county's largest town, base 15.5°C (our sum).

Empty cavities

Share of BERs for pre-2011 homes whose main wall is a cavity with no insulation. These are the walls the cavity grant is for.

  1. Louth7.9%
  2. Donegal6.6%
  3. Mayo6%
  4. Clare5.9%
  5. Kerry5.7%
  6. Galway5.4%
  7. Limerick5.3%
  8. Offaly5.3%
  9. Westmeath5.3%
  10. Monaghan5%
  11. Roscommon5%
  12. Cork4.7%
  13. Laois4.6%
  14. Waterford4.5%
  15. Carlow4.4%
  16. Tipperary4.4%
  17. Wexford3.9%
  18. Longford3.8%
  19. Dublin3.7%
  20. Kilkenny3.7%
  21. Meath3.7%
  22. Wicklow3.7%
  23. Sligo3.5%
  24. Cavan3.3%
  25. Kildare3.3%
  26. Leitrim3.2%

Hollow block

Share recorded as concrete hollow block. No continuous cavity, so no pumped fill: internal or external insulation instead.

  1. Meath11%
  2. Kildare10.9%
  3. Wicklow7.5%
  4. Dublin7.2%
  5. Laois6.4%
  6. Westmeath5.5%
  7. Offaly3.5%
  8. Carlow3.4%
  9. Louth2.8%
  10. Cavan2.6%
  11. Monaghan2.6%
  12. Cork2.2%
  13. Kilkenny1.3%
  14. Longford1.3%
  15. Limerick1.2%
  16. Clare1.1%
  17. Tipperary1.1%
  18. Wexford1.1%
  19. Sligo1%
  20. Waterford1%
  21. Leitrim0.6%
  22. Galway0.5%
  23. Mayo0.4%
  24. Roscommon0.4%
  25. Kerry0.3%
  26. Donegal0%

Each county in five numbers

Savings are our calculator's, for a gas-heated semi-D built before 1978 with 88 m² of empty cavity wall, the median on BER certificates.

  • Carlow

    • 19,923 homes built before 2011, 90% of 22,174; 37% before 1981 (Census 2022)
    • 4.4% empty cavity, 34% part-insulated, 17% filled, 3.4% hollow block on 9,759 BERs
    • 23% rated E, F or G; 16% of recorded walls have no insulation
    • 845 grant BERs in 2026 to 29 October (42.4 per 1,000 pre-2011 homes)
    • 1,969 degree days at Carlow: a gas-heated semi-D built before 1978 saves about €400–€590 a year

  • Cavan

    • 26,232 homes built before 2011, 91% of 28,776; 34% before 1981 (Census 2022)
    • 3.3% empty cavity, 35% part-insulated, 19% filled, 2.6% hollow block on 11,443 BERs
    • 25% rated E, F or G; 16% of recorded walls have no insulation
    • 1,007 grant BERs in 2026 to 29 October (38.4 per 1,000 pre-2011 homes)
    • 2,159 degree days at Cavan: a gas-heated semi-D built before 1978 saves about €430–€640 a year

  • Clare

    • 42,490 homes built before 2011, 91% of 46,441; 39% before 1981 (Census 2022)
    • 5.9% empty cavity, 36% part-insulated, 24% filled, 1.1% hollow block on 20,329 BERs
    • 27% rated E, F or G; 19% of recorded walls have no insulation
    • 1,917 grant BERs in 2026 to 29 October (45.1 per 1,000 pre-2011 homes)
    • 1,843 degree days at Ennis: a gas-heated semi-D built before 1978 saves about €370–€550 a year

  • Cork

    • 189,937 homes built before 2011, 90% of 210,918; 43% before 1981 (Census 2022)
    • 4.7% empty cavity, 32% part-insulated, 17% filled, 2.2% hollow block on 80,343 BERs
    • 27% rated E, F or G; 25% of recorded walls have no insulation
    • 8,967 grant BERs in 2026 to 29 October (47.2 per 1,000 pre-2011 homes)
    • 1,755 degree days at Cork: a gas-heated semi-D built before 1978 saves about €350–€520 a year Full Cork page

  • Donegal

    • 56,530 homes built before 2011, 92% of 61,575; 33% before 1981 (Census 2022)
    • 6.6% empty cavity, 42% part-insulated, 31% filled, 0.0% hollow block on 25,554 BERs
    • 25% rated E, F or G; 17% of recorded walls have no insulation
    • 2,817 grant BERs in 2026 to 29 October (49.8 per 1,000 pre-2011 homes)
    • 2,211 degree days at Letterkenny: a gas-heated semi-D built before 1978 saves about €440–€660 a year

  • Dublin

    • 463,112 homes built before 2011, 89% of 518,490; 48% before 1981 (Census 2022)
    • 3.7% empty cavity, 19% part-insulated, 6% filled, 7.2% hollow block on 238,576 BERs
    • 23% rated E, F or G; 28% of recorded walls have no insulation
    • 13,766 grant BERs in 2026 to 29 October (29.7 per 1,000 pre-2011 homes)
    • 1,825 degree days at Dublin: a gas-heated semi-D built before 1978 saves about €370–€550 a year Full Dublin page

  • Galway

    • 89,021 homes built before 2011, 90% of 98,654; 33% before 1981 (Census 2022)
    • 5.4% empty cavity, 43% part-insulated, 26% filled, 0.5% hollow block on 39,045 BERs
    • 25% rated E, F or G; 16% of recorded walls have no insulation
    • 4,621 grant BERs in 2026 to 29 October (51.9 per 1,000 pre-2011 homes)
    • 1,860 degree days at Galway: a gas-heated semi-D built before 1978 saves about €370–€560 a year Full Galway page

  • Kerry

    • 53,155 homes built before 2011, 91% of 58,179; 39% before 1981 (Census 2022)
    • 5.7% empty cavity, 37% part-insulated, 31% filled, 0.3% hollow block on 24,009 BERs
    • 26% rated E, F or G; 17% of recorded walls have no insulation
    • 2,766 grant BERs in 2026 to 29 October (52.0 per 1,000 pre-2011 homes)
    • 1,673 degree days at Tralee: a gas-heated semi-D built before 1978 saves about €340–€500 a year

  • Kildare

    • 70,654 homes built before 2011, 86% of 82,543; 28% before 1981 (Census 2022)
    • 3.3% empty cavity, 22% part-insulated, 10% filled, 10.9% hollow block on 29,237 BERs
    • 16% rated E, F or G; 15% of recorded walls have no insulation
    • 3,631 grant BERs in 2026 to 29 October (51.4 per 1,000 pre-2011 homes)
    • 2,093 degree days at Naas: a gas-heated semi-D built before 1978 saves about €420–€630 a year

  • Kilkenny

    • 33,590 homes built before 2011, 92% of 36,685; 41% before 1981 (Census 2022)
    • 3.7% empty cavity, 29% part-insulated, 21% filled, 1.3% hollow block on 11,953 BERs
    • 26% rated E, F or G; 18% of recorded walls have no insulation
    • 1,493 grant BERs in 2026 to 29 October (44.4 per 1,000 pre-2011 homes)
    • 1,961 degree days at Kilkenny: a gas-heated semi-D built before 1978 saves about €390–€590 a year

  • Laois

    • 27,915 homes built before 2011, 90% of 31,112; 32% before 1981 (Census 2022)
    • 4.6% empty cavity, 37% part-insulated, 13% filled, 6.4% hollow block on 11,122 BERs
    • 24% rated E, F or G; 17% of recorded walls have no insulation
    • 1,122 grant BERs in 2026 to 29 October (40.2 per 1,000 pre-2011 homes)
    • 2,080 degree days at Portlaoise: a gas-heated semi-D built before 1978 saves about €420–€620 a year

  • Leitrim

    • 12,590 homes built before 2011, 93% of 13,589; 36% before 1981 (Census 2022)
    • 3.2% empty cavity, 29% part-insulated, 27% filled, 0.6% hollow block on 6,283 BERs
    • 30% rated E, F or G; 20% of recorded walls have no insulation
    • 599 grant BERs in 2026 to 29 October (47.6 per 1,000 pre-2011 homes)
    • 2,102 degree days at Carrick-on-Shannon: a gas-heated semi-D built before 1978 saves about €420–€630 a year

  • Limerick

    • 69,742 homes built before 2011, 91% of 76,295; 43% before 1981 (Census 2022)
    • 5.3% empty cavity, 33% part-insulated, 21% filled, 1.2% hollow block on 32,001 BERs
    • 24% rated E, F or G; 18% of recorded walls have no insulation
    • 3,334 grant BERs in 2026 to 29 October (47.8 per 1,000 pre-2011 homes)
    • 1,837 degree days at Limerick: a gas-heated semi-D built before 1978 saves about €370–€550 a year Full Limerick page

  • Longford

    • 14,615 homes built before 2011, 90% of 16,206; 35% before 1981 (Census 2022)
    • 3.8% empty cavity, 33% part-insulated, 24% filled, 1.3% hollow block on 6,932 BERs
    • 26% rated E, F or G; 15% of recorded walls have no insulation
    • 463 grant BERs in 2026 to 29 October (31.7 per 1,000 pre-2011 homes)
    • 2,094 degree days at Longford: a gas-heated semi-D built before 1978 saves about €420–€630 a year

  • Louth

    • 43,776 homes built before 2011, 89% of 49,332; 41% before 1981 (Census 2022)
    • 7.9% empty cavity, 27% part-insulated, 22% filled, 2.8% hollow block on 17,886 BERs
    • 23% rated E, F or G; 20% of recorded walls have no insulation
    • 2,191 grant BERs in 2026 to 29 October (50.1 per 1,000 pre-2011 homes)
    • 1,951 degree days at Drogheda: a gas-heated semi-D built before 1978 saves about €390–€580 a year

  • Mayo

    • 47,576 homes built before 2011, 91% of 51,996; 38% before 1981 (Census 2022)
    • 6.0% empty cavity, 40% part-insulated, 23% filled, 0.4% hollow block on 21,451 BERs
    • 29% rated E, F or G; 21% of recorded walls have no insulation
    • 2,118 grant BERs in 2026 to 29 October (44.5 per 1,000 pre-2011 homes)
    • 2,028 degree days at Castlebar: a gas-heated semi-D built before 1978 saves about €410–€610 a year

  • Meath

    • 61,744 homes built before 2011, 85% of 72,549; 30% before 1981 (Census 2022)
    • 3.7% empty cavity, 25% part-insulated, 16% filled, 11.0% hollow block on 22,788 BERs
    • 19% rated E, F or G; 16% of recorded walls have no insulation
    • 3,101 grant BERs in 2026 to 29 October (50.2 per 1,000 pre-2011 homes)
    • 2,048 degree days at Navan: a gas-heated semi-D built before 1978 saves about €410–€610 a year

  • Monaghan

    • 20,680 homes built before 2011, 90% of 22,855; 42% before 1981 (Census 2022)
    • 5.0% empty cavity, 29% part-insulated, 25% filled, 2.6% hollow block on 7,680 BERs
    • 26% rated E, F or G; 19% of recorded walls have no insulation
    • 828 grant BERs in 2026 to 29 October (40.0 per 1,000 pre-2011 homes)
    • 2,182 degree days at Monaghan: a gas-heated semi-D built before 1978 saves about €440–€650 a year

  • Offaly

    • 26,435 homes built before 2011, 92% of 28,702; 41% before 1981 (Census 2022)
    • 5.3% empty cavity, 30% part-insulated, 23% filled, 3.5% hollow block on 10,115 BERs
    • 33% rated E, F or G; 20% of recorded walls have no insulation
    • 1,268 grant BERs in 2026 to 29 October (48.0 per 1,000 pre-2011 homes)
    • 2,046 degree days at Tullamore: a gas-heated semi-D built before 1978 saves about €410–€610 a year

  • Roscommon

    • 23,885 homes built before 2011, 92% of 25,975; 38% before 1981 (Census 2022)
    • 5.0% empty cavity, 35% part-insulated, 23% filled, 0.4% hollow block on 9,658 BERs
    • 33% rated E, F or G; 24% of recorded walls have no insulation
    • 998 grant BERs in 2026 to 29 October (41.8 per 1,000 pre-2011 homes)
    • 2,088 degree days at Roscommon: a gas-heated semi-D built before 1978 saves about €420–€620 a year

  • Sligo

    • 24,706 homes built before 2011, 92% of 26,801; 38% before 1981 (Census 2022)
    • 3.5% empty cavity, 29% part-insulated, 23% filled, 1.0% hollow block on 12,337 BERs
    • 26% rated E, F or G; 19% of recorded walls have no insulation
    • 1,055 grant BERs in 2026 to 29 October (42.7 per 1,000 pre-2011 homes)
    • 2,032 degree days at Sligo: a gas-heated semi-D built before 1978 saves about €410–€610 a year

  • Tipperary

    • 57,648 homes built before 2011, 93% of 62,056; 45% before 1981 (Census 2022)
    • 4.4% empty cavity, 29% part-insulated, 23% filled, 1.1% hollow block on 22,651 BERs
    • 34% rated E, F or G; 24% of recorded walls have no insulation
    • 2,864 grant BERs in 2026 to 29 October (49.7 per 1,000 pre-2011 homes)
    • 1,959 degree days at Clonmel: a gas-heated semi-D built before 1978 saves about €390–€590 a year

  • Waterford

    • 43,265 homes built before 2011, 91% of 47,682; 41% before 1981 (Census 2022)
    • 4.5% empty cavity, 30% part-insulated, 24% filled, 1.0% hollow block on 20,572 BERs
    • 23% rated E, F or G; 16% of recorded walls have no insulation
    • 1,977 grant BERs in 2026 to 29 October (45.7 per 1,000 pre-2011 homes)
    • 1,781 degree days at Waterford: a gas-heated semi-D built before 1978 saves about €360–€530 a year

  • Westmeath

    • 31,156 homes built before 2011, 92% of 34,003; 38% before 1981 (Census 2022)
    • 5.3% empty cavity, 26% part-insulated, 18% filled, 5.5% hollow block on 14,538 BERs
    • 25% rated E, F or G; 18% of recorded walls have no insulation
    • 1,369 grant BERs in 2026 to 29 October (43.9 per 1,000 pre-2011 homes)
    • 2,162 degree days at Mullingar: a gas-heated semi-D built before 1978 saves about €430–€650 a year

  • Wexford

    • 53,211 homes built before 2011, 90% of 59,081; 34% before 1981 (Census 2022)
    • 3.9% empty cavity, 38% part-insulated, 21% filled, 1.1% hollow block on 24,466 BERs
    • 27% rated E, F or G; 15% of recorded walls have no insulation
    • 2,457 grant BERs in 2026 to 29 October (46.2 per 1,000 pre-2011 homes)
    • 1,844 degree days at Wexford: a gas-heated semi-D built before 1978 saves about €370–€550 a year

  • Wicklow

    • 47,743 homes built before 2011, 88% of 54,059; 41% before 1981 (Census 2022)
    • 3.7% empty cavity, 20% part-insulated, 10% filled, 7.5% hollow block on 20,972 BERs
    • 25% rated E, F or G; 23% of recorded walls have no insulation
    • 1,947 grant BERs in 2026 to 29 October (40.8 per 1,000 pre-2011 homes)
    • 1,883 degree days at Bray: a gas-heated semi-D built before 1978 saves about €380–€560 a year

Work it out for your county

Pick your county in the calculator: the degree days change with it. Then tap the button and one SEAI-registered contractor who covers your area will price the job.

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Your grant, cost and saving

SEAI grant€1,300
Typical cost SEAI median€1,585
Left to pay€285
Saving a year€420–€620
Heat kept in a year2,900–3,730 kWh
Pays back in0.5–0.7 years

At €7.50 to €13 per m² incl. VAT (one Irish cost guide, 31 July 2026): €660–€1,144 for 88 m².

Heat lost through the walls each year, on SEAI's U-values U-value 1.78 → 0.60, 2,079 degree days. Physics only: the heat and saving above keep 56% to 72% of the gap.

Now7,820 kWh
After2,630 kWh

Homes built or first lived in from 2011 can't get this SEAI grant. The saving still applies if you pay for the work yourself.

Get a price for these walls
How this is worked out

Grant: SEAI's fixed amounts, standard or higher rate (seai.ie, checked 29 October 2026). Typical cost: SEAI's median cost of cavity wall insulation for your home type, January to June 2026 (SEAI's median costs PDF); SEAI doesn't say if VAT is in it. The per m² range is ShamFix's, VAT included.

Heat kept in: wall area × the drop in U-value × your county's degree days × 24, which turns degree days into degree hours. The U-values are the ones SEAI's BER software uses: an empty 300 mm cavity wall is 1.78 if built before 1978, 1.10 from 1978 to 1982, 0.60 to 1993 and 0.55 to 2004 (DEAP Table 2.21); filled, it's 0.60 before 1978 and 0.37 after (SEAI onsite upgrade defaults). Later homes were built with some insulation, so filling them gains less. SEAI's guide asks for 0.27 W/m²K after the work (SEAI guide); we use the software defaults instead, which are higher, so the saving here leans low. The area starts at the median wall area on BER certificates for homes of your type with an empty cavity (SEAI BER Research Tool, the full public file downloaded 29 October 2026: 751,700 certificates for existing homes built before 2011, leaving out the BERs done for grant claims); change it to yours. Degree days: Met Éireann's 1991–2020 monthly temperatures for your county, base 15.5°C (our sum).

Saving: the heat ÷ your heating's efficiency × the unit price. Prices are SEAI's of 1 July 2026, VAT included (SEAI fuel cost comparison). Boilers run at 78% to 90% (gas) and 79% to 86% (oil), the middle half of boilers on those certificates; heat pumps at 2.5 to 4 units of heat per unit of electricity (SEAI's range). Then we keep only 56% to 72% of it, because SEAI's own study of 210 grant homes measured savings 36% (±8%) below the engineering estimate (Scheer, Clancy and Ní Hógáin, 2013). It's an estimate, not a quote.

Check your grant

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Four taps show the SEAI grant for your home. We pass your number to one SEAI-registered contractor who covers your county.

  1. You tap four answersHome type, when it was built and lived in, and any earlier wall grant.
  2. One contractor rings youThey survey the walls, usually with a camera look into the cavity.
  3. You decideA written quote with VAT stated. Nothing is booked until you say yes.

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What type of home is it?

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County questions

Is the cavity wall grant different in each county?

No. SEAI pays the same fixed amounts everywhere: €700 to €1,800 by home type, with higher rates for qualifying welfare recipients and HAP or RAS homes (seai.ie).

Which county has the most empty cavity walls?

On BER certificates for homes built before 2011, Louth: 7.9% record an empty, uninsulated cavity. Leitrim has the lowest share, 3.2%.

Where is hollow block most common?

Meath, at 11.0% of certificates, then Kildare at 10.9%. Hollow block can't be pumped under SEAI's standards; internal or external insulation are the grant routes.

Why does the saving change by county?

The heat a wall loses follows the weather. 2,211 degree days at Letterkenny against 1,673 at Tralee on Met Éireann's 1991–2020 averages (our sum), so the same wall saves about 32% more in Donegal.

How these figures were worked out

  • BER figures: we downloaded SEAI's full public BER file on 29 October 2026 and counted certificates for existing homes built before 2011, by county and by the main (first) wall on each certificate. We left out the BERs done for grant claims, so homes that were just upgraded with a grant don't skew the picture. A home can appear more than once if it had more than one BER.
  • An empty cavity is a 300 or 425 mm cavity wall with a U-value of 1.0 W/m²K or more; a part-insulated cavity is one below that. 'Other or not recorded' covers certificates with an unknown or other wall type.
  • Dublin is Co. Dublin plus every Dublin postal district; Cork, Limerick, Galway and Waterford include their cities.
  • Grant BERs count every certificate with the purpose 'Grant Support' in 2026, every SEAI home grant, walls included.
  • Degree days are our sum from Met Éireann's 1 km grid of 1991–2020 monthly mean temperatures, within 3 km of the county's largest town.
Where these numbers come from (10 public sources, checked 29 October 2026)
  1. SEAI BER Research Tool (public BER file) ndber.seai.ie
  2. CSO Census 2022, households by type and year built data.cso.ie
  3. Met Éireann 1991–2020 averages met.ie
  4. SEAI wall insulation grant page seai.ie
  5. SEAI median costs of individual upgrades, Jan–Jun 2026 seai.ie
  6. SEAI DEAP guide: default wall U-values deapguide.seai.ie
  7. SEAI DEAP onsite defaults for upgraded homes, 2023 seai.ie
  8. SEAI homeowner's guide to wall insulation seai.ie
  9. SEAI domestic fuel cost comparison, 1 July 2026 seai.ie
  10. Scheer, Clancy and Ní Hógáin (SEAI), Energy Efficiency, 2013 link.springer.com
Sources (1)

Prices and facts on this page were checked against these published pages. We are not connected to these businesses.

  1. ShamFix: shamfix.ie

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