Internal wall insulation

When to choose it

Solid-walled homes — pre-1930s brick or stone — where the outside cannot be changed: conservation areas, listed buildings, terraces where the front elevation matters, or where you want to do one room at a time.

How it is done

Insulated plasterboard, or a stud with insulation between and a vapour control layer, fixed to the inside of external walls. Typically 60–100mm, so the room loses a little floor space. Window reveals, floor junctions and ceiling junctions must be insulated too, or the cold bridges left behind cause condensation and mould at exactly those points.

Moisture

Solid walls are meant to dry inward and outward. Insulating internally keeps the wall colder and wetter. In exposed or damp walls a breathable system — wood fibre, lime — is safer than a vapour-tight PIR board. This is a design decision, not an installer preference.

Cost and funding

£4,000–£12,000 for a typical home's external walls; can be phased by room. Solid wall insulation is a funded measure for eligible households under whole-house schemes. Current routes.

Questions homeowners ask