Wall insulation glossary

The terms you meet on SEAI's wall insulation grant pages and in a contractor's quote, explained in plain English.

Cavity fill, dry lining, ETICS wrap, 0.27 W/m²K U-value, MPRN, BER and NSAI Agrément explained.

Free, no obligation. One SEAI-registered contractor prices it, not five.

€8,000external wall grant for a detached house
€4,500internal (dry lining), detached
€1,800cavity fill, detached
24%of older homes have solid or hollow block walls

0.27 W/m²K Target Wall U-Value 8-Month Grant Offer Validity Window Better Energy Homes vs One Stop Shop Cavity Wall Grant (€700 to €1,800)Declaration of Works (Wall Insulation)External Wall Insulation Grant (€3,000 to €8,000)Higher Grant Rate (HAP, RAS & Qualifying Welfare)Internal Wall Insulation / Dry Lining Grant (€1,500 to €4,500)Interstitial Condensation & Vapour Control Layer Mixed-Wall Measure Rule MPRN (Meter Point Reference Number)NSAI Agrément Certified System & Installer Pre-2011 Build & Occupation Cut-Off Second Wall Insulation Measure Traditional Homes Solid-Wall Pilot

0.27 W/m²K Target Wall U-Value

Maximum post-upgrade thermal transmittance permitted under SEAI's Better Energy Homes technical standards for grant-aided cavity wall pumping, internal dry lining (IWI) or external wall insulation (EWI).

8-Month Grant Offer Validity Window

Strict SEAI timeline starting on the date your online grant offer letter is issued: all wall insulation works, the post-works BER assessment and the online Declaration of Works submission must be completed within 8 calendar months.

Better Energy Homes vs One Stop Shop

SEAI's two grant routes: under Better Energy Homes you manage individual upgrades yourself and claim the grant back after completion; under a One Stop Shop the provider manages a whole-home upgrade to a B2 BER and deducts the grant upfront.

Cavity Wall Grant (€700 to €1,800)

Fixed SEAI grant for pumping bonded bead into an existing twin-leaf masonry cavity wall: €1,800 detached, €1,300 semi-D or end of terrace, €850 mid-terrace and €700 apartment (rising to €2,300 / €1,700 / €1,100 / €900 on the higher welfare/HAP/RAS rate).

Declaration of Works (Wall Insulation)

Official SEAI completion form signed by the registered wall insulation contractor and the BER assessor confirming that every external wall reached 0.27 W/m²K or lower using an NSAI Agrément certified system.

External Wall Insulation Grant (€3,000 to €8,000)

SEAI's highest wall grant, paid for wrapping the outside of the home in certified ETICS insulation board and mesh-reinforced render: €8,000 detached, €6,000 semi-D or end of terrace, €3,500 mid-terrace and €3,000 apartment.

Higher Grant Rate (HAP, RAS & Qualifying Welfare)

Increased SEAI cavity and attic insulation grant tier introduced on 6 October 2026 for homeowners receiving qualifying Department of Social Protection payments and landlords whose property is rented under HAP or RAS.

Internal Wall Insulation / Dry Lining Grant (€1,500 to €4,500)

Fixed SEAI grant for fixing insulated plasterboard or an insulated stud-and-vapour-membrane lining to the inside face of all external walls: €4,500 detached, €3,500 semi-D or end of terrace, €2,000 mid-terrace and €1,500 apartment.

Interstitial Condensation & Vapour Control Layer

Moisture risk behind internal dry lining where warm indoor air reaches the cold masonry face; prevented by fitting a continuous polythene or smart vapour-control membrane on the warm side of the insulation and insulating window reveals.

Mixed-Wall Measure Rule

SEAI rule for houses with two wall types (for example, a cavity-wall main house with a solid-block rear extension): every external wall must still be insulated, and SEAI pays the single grant belonging to the measure that covers the larger wall area.

MPRN (Meter Point Reference Number)

The 11-digit ESB Networks electricity meter number used by SEAI to identify your property, check its pre-2011 occupation history and verify which wall grants have already been paid at that address.

NSAI Agrément Certified System & Installer

Dual certification required on every grant-funded wall job: both the insulation product (bonded bead, dry-lining laminate or ETICS wrap) and the installing contractor must hold current NSAI Agrément registration.

Pre-2011 Build & Occupation Cut-Off

Statutory eligibility rule for all three SEAI wall insulation grants requiring the house or apartment to have been built and occupied before 1 January 2011 (31 December 2010 or earlier).

Second Wall Insulation Measure

SEAI rule allowing a pre-2011 home that previously claimed a cavity wall grant to claim a second grant later for internal dry lining or external wall wrap to bring older walls up to modern comfort standards.

Traditional Homes Solid-Wall Pilot

Separate SEAI guidance route for pre-1940 solid stone, rubble or single-leaf brick buildings where vapour-open lime renders, wood-fibre boards or capillary-active internal linings are needed instead of standard petrochemical boards.