Internal Wall Insulation

The answer when the outside of the house has to stay as it is.

How It Works

Insulation fixed to the inside face of the external walls, room by room.

Not every home can be insulated externally. Protected structures, houses built right up to a boundary, properties where the brickwork or stone is the whole character of the building — for all of these, the insulation has to go on the inside.

Insulated plasterboard, or an insulation layer with a separate board finish, is fixed to the inside face of the external walls. Joints are sealed, a vapour control layer is maintained, and the wall is skimmed and decorated as normal. Work is carried out room by room, so the house stays liveable throughout. Skirtings, architraves, sockets, switches and radiators are removed and reinstated as part of the job.

It delivers the same thermal improvement as its external counterpart. It asks more of the detailing and costs you a little floor area, but on the right house it’s the right call.

When Internal Insulation Is the Right Choice

Where external insulation is not possible, permitted or appropriate.

  • Protected structures and period homes where the façade can’t be altered
  • Terraced and mid-terrace houses with no external access to the front or party walls
  • Properties on the boundary line where building outward isn’t possible
  • Phased projects where a homeowner wants to upgrade one or two rooms now and more later

It’s also common to mix approaches — external insulation to the rear and gables, internal to a protected front elevation.

A typical internal build-up takes 60–100mm off each external wall. In a large room that’s barely noticeable. In a small bathroom or a narrow hall it needs thinking about, and we’ll show you the numbers room by room before you commit.

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Getting the Detail Right

Internal wall insulation is unforgiving of shortcuts. Three things decide whether a job performs.

Continuity at junctions. Where an internal wall or a floor meets the external wall, heat can bypass the insulation. These junctions need to be insulated back into the room — returns at reveals, at floor and ceiling lines, and around party walls.

Vapour control. The insulation makes the masonry behind it colder. Without a properly sealed vapour control layer, moist internal air reaches that cold surface and condenses inside the build-up. That’s how interstitial condensation problems start, and they’re expensive to fix.

Ventilation. Tightening the internal envelope changes how the house breathes. Ventilation has to be assessed alongside the insulation, not after it.

Grants and eligibility

Internal wall insulation is supported under SEAI grant schemes, both individually and as part of a One Stop Shop deep retrofit. We handle eligibility, application and compliance documentation as part of the service.

Interior of a property stripped back during renovation

Frequently Asked Questions

Is internal insulation as good as external?

On thermal performance the insulation itself performs the same. External has the edge on continuity because it wraps the junctions automatically. Internal can match it, but only with careful detailing — which is exactly what we specify for.

Do I have to move out?

No. We work room by room. You’ll need to clear the rooms being worked on, but the house stays occupied.

What happens to my radiators and sockets?

Removed and reinstated. Radiators are typically brought forward onto the new wall line; electrical points are extended and refitted.

Will I lose my window boards and skirtings?

Skirtings and architraves come off and are refitted or replaced. Window boards usually need replacing because the reveal depth changes.

Talk to us about internal wall insulation.

Call 051 850722. We’ll assess the walls, the junctions and the ventilation together, and show you the build-up room by room.

Why ENCON

Detailing and vapour control specified before a board goes up.