EPC D to C in a terraced house

Terraces are the cheapest house type to lift from D to C — when the walls cooperate. A mid-terrace only exposes two walls to the weather; the party walls on either side barely lose heat in the SAP model. The whole question is what those two exposed walls are made of.

First, date your walls

Roughly speaking, terraces built before the 1920s have solid brick walls; terraces from the 1930s onward usually have cavities. Check the brick pattern: alternating long and short bricks (header bond) in the same course suggests solid walls, while uniform stretcher bond usually means a cavity. Your EPC already records the assessor's verdict under "Walls". The two cases lead to entirely different plans.

Worked example: 1930s mid-terrace, cavity walls, D 62

Three-bed mid-terrace, gas combi boiler from 2015, 100mm of loft insulation, double glazed in the 2000s, no room thermostat. Gap to C: 7 points.

Total: around £1,970 plus £80–£100 for the new certificate. Note the cavity fill price — a mid-terrace has so little exposed wall that installers quote near their minimum charge, which is why terrace cavity fill is often under £1,000 while a detached house pays £2,600 for the same measure. Even stopping after the loft top-up, this house sits one point off C; the cavity fill provides margin against assessor-to-assessor variation, which is worth having.

The Victorian exception: solid walls

A pre-1920 solid-wall terrace at D 56–60 is a harder project. The cheap rungs still apply — controls, lighting, loft — but they typically leave you at 63–66, short of the line. The remaining options:

• Solar PV — usually the cheapest remaining points if the roof faces anywhere south of due east/west. A 2–3 kWp array on a terrace roof at £4,000–£5,500 typically adds 6–10 points and finishes the job without touching the walls.
• Internal wall insulation on the front and rear elevations only — £4,000–£8,000 on a terrace, 8–14 points, but it shaves floor space off every treated room and needs careful moisture design around joist ends.
• External wall insulation — rarely viable on the street elevation of a period terrace (planning and appearance), sometimes used on the rear only.

For most owners the realistic Victorian terrace route is: cheap measures plus solar, total £5,000–£7,000. Conservation areas complicate the solar option — check with the planning authority before quoting. The measures ranking has full notes on each option.

Terrace-specific pitfalls

• End-terraces are halfway to semis. Three exposed walls instead of two — costs and gains both scale up. Treat an end-terrace plan more like the semi-detached example.
• Rear extensions with flat roofs often hide uninsulated roof area that drags the score. Insulating during any re-roofing is near-free points; retrofitting is expensive.
• No loft access in some older terraces means the assessor must assume the worst. Fitting a hatch and showing the insulation can recover points you have already paid for.
• Narrow returns and alleyway walls count as exposed wall. Make sure the assessor records the layout accurately — and keep the cavity guarantee certificate where it can be found at reassessment.

Letting the property? Terraces dominate the private rented stock in many northern cities, and the proposed 2030 band C requirement would catch a D 62 terrace squarely — the landlord page covers timing and cost caps. For budgets across every route, see the cost ladder.