Internal wall insulation vs external — which is right for a Victorian Leeds terrace?

If you live in a Victorian or Edwardian solid-wall terrace anywhere across Leeds — Headingley, Roundhay, Chapel Allerton, Burley — you'll be losing 35–45% of your home's heat straight through the brickwork. Wall insulation fixes it, but which type? Here's a fitter's-eye view of the trade-offs.

The short answer for most Leeds terraces

Internal Wall Insulation (IWI) is right for 80% of the Leeds solid-wall terraces we survey. Conservation areas, listed exteriors, brickwork you actually want to keep visible, and the fact that EWI on a mid-terrace is structurally awkward — all push the decision indoors.

Internal Wall Insulation — the upside

• No scaffolding, no exterior change, no planning hassle in conservation areas
• Done one room at a time — no need to vacate the house
• Typically £70–£120/m² supplied and fitted
• Cuts heat loss through that wall by 50–60%
• Rooms warm up faster — you feel the difference within days

Internal Wall Insulation — the trade-offs

• You lose 50–100 mm of room depth on every external wall
• Skirting, sockets, switches and architraves all need re-fitting
• Vapour control detailing has to be done properly or you get condensation behind the boards
• Cold bridges at floor/ceiling junctions need careful detailing

External Wall Insulation — when it makes sense

EWI works brilliantly on end-of-terrace and semi-detached properties where the gable end can be wrapped. It avoids any internal disruption, eliminates cold bridges, and gives the building a fresh render finish. But it costs roughly twice as much per m², usually needs scaffolding, and changes the look of the house — which rules it out for most period terraces and conservation areas.

How we spec IWI properly

Every IWI job we install is detailed to PAS 2030 / 2035 standards. The system depends on the property — PIR board for max U-value in tight rooms, mineral wool when breathability matters, woodfibre on truly historic stock. Vapour control layers are continuous, perimeters are taped, services are first-fixed cleanly. Done right, IWI lasts the life of the house.