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Internal vs External Wall Insulation

External wall insulation wraps the outside of the house, doesn't reduce room sizes and deals with cold spots best, but costs more and changes how the house looks. Internal insulation suits homes where the outside can't change, such as period homes, but makes rooms slightly smaller.

  • Cost and grants
  • Disruption
  • Room size
  • Which homes suit each
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Emergency Trade is independent and not part of SEAI or any council. Always confirm details with the official source before applying.

Side-by-side comparison

InternalExternal
Typical cost (semi)€6,000–€18,000€18,000–€28,000
SEAI grant (semi)€3,500€6,000
Room sizeReduced slightlyUnchanged
AppearanceOutside unchangedNew render finish
DisruptionInside the home, room by roomOutside, with scaffolding
Best forPeriod homes and protected facadesSolid or hollow-block walls where the outside can change

Choose internal if

  • The outside of the house must stay the same
  • You're renovating rooms anyway
  • You're on a tighter budget

Choose external if

  • You want the biggest improvement without losing room space
  • You'd like to refresh the outside of the house
  • You can stay living normally inside during the work

See the insulation grants.

Frequently asked questions

Which is better, internal or external insulation?

External usually performs better and doesn't reduce room sizes, but internal suits homes where the outside can't change.

Are there grants for both?

Yes. SEAI offers grants for both internal and external wall insulation.

Will internal insulation cause damp?

Not when designed properly with suitable materials and ventilation, especially in older solid-wall homes.

Find vetted contractors for this work

By area:

  • North Dublin City: Artane, Cabra, Clontarf, Coolock, Drumcondra, East Wall, Fairview, Glasnevin, Phibsborough, Stoneybatter
  • Dublin North Coast: Raheny, Baldoyle, Donaghmede, Howth, Sutton, Portmarnock, Malahide
  • South West Dublin: Tallaght, Citywest, Firhouse, Knocklyon, Ballyboden, Templeogue, Walkinstown, Kimmage, Rathfarnham, Terenure
  • Stillorgan, Sandyford & Foxrock: Mount Merrion, Stillorgan, Goatstown, Sandyford, Cherrywood, Cabinteely, Foxrock, Deansgrange
  • West Dublin & Leixlip: Chapelizod, Palmerstown, Lucan, Leixlip, Adamstown, Clondalkin
  • Dún Laoghaire & South Coast: Blackrock, Booterstown, Monkstown, Dún Laoghaire, Dalkey, Killiney
  • Dublin 15: Blanchardstown, Castleknock, Mulhuddart, Ongar, Hansfield, Ashtown
  • North County Dublin: Swords, Lusk, Rush, Skerries
  • South Dublin City: Ballsbridge, Donnybrook, Sandymount, Ranelagh, Rathgar, Harold's Cross, Churchtown, Dundrum

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