Multifoil in listed and historic homes — the breathable retrofit option

If you own a listed or historic home and you've been told insulation is off the table, this page is for you. Listed-building consent is where most insulation products hit a wall — and for good reason. Conservation officers across Essex, Suffolk, Kent and Cambridgeshire — counties packed with Grade II timber-frames, pargeted farmhouses, flint cottages and Victorian villas — have a long memory for retrofits gone wrong. Spray foam in a thatched roof that trapped moisture. Cellulose in a timber frame that drove up the relative humidity. Mineral wool pressed tight against breathable lath and plaster.

Multifoil is the exception they increasingly say yes to. Thin, breathable, reversible, and — crucially — it can be removed without trace if the property ever needs to revert. Here's why it's become the conservation officer's default answer, what it actually costs, and where we'd still suggest not using it.

Multifoil is one of the few retrofit insulations those officers still approve. It is thin, fully reversible, vapour-controlled rather than vapour-closed, and — critically — does not load moisture onto the historic fabric. Here is why it works for listed homes, what we install, and what the paperwork looks like.

Why listed homes are different

Pre-1919 UK buildings were built to breathe. Lime mortar, lime plaster, timber frame, solid brick in stretcher bond, thatch, or oak-boarded floors. Moisture moves through the fabric in both directions — inside to outside in winter, outside to inside in summer. Trap moisture at any point with a vapour-closed material (PIR, EPS, closed-cell spray foam) and you create a dew-point zone that rots timber, spalls brick, or delaminates lime plaster within 5-15 years.

Historic England's retrofit guidance and the SPAB (Society for the Protection of Ancient Buildings) both take the same line: use breathable or vapour-controlled materials only, keep the fabric dryable in both directions, and prefer reversible systems. Multifoil meets all three criteria — and mineral wool does not, because even though it is vapour-open, its 170mm build-up rarely fits on a Grade II rafter.

Which multifoil we fit on listed work

Not every multifoil is suitable for historic work. The three products we specify on OMEGA listed-building jobs are: Actis Hybris (105 or 155 grade), SuperFOIL SF60, and TLX Silver for breathable-membrane applications. All three carry BBA certification for the specific application we install them in, which matters because your planning approval will reference the BBA number.

What we avoid on listed work: closed-cell spray foam (permanently alters the fabric and is now effectively a mortgageability killer on listed homes), PIR-only builds without a continuous VCL (wrong moisture profile), and imported unbranded multifoils with no BBA certification (planning officers reject them on sight).

Typical applications — what we retrofit where

Rafters of a Grade II pitched roof

Actis Hybris HControl 105 between rafters (85mm thickness, fitted with the required 20mm air gap), cross-battened, then Fermacell or clay-board finish to match the historic character. Build-up 105mm total. U-value 0.20 W/m²K. Preserves rafter depth; no need to deepen the structure.

Solid brick gable end from inside

SuperFOIL SF60 battened to the inner leaf with a 25mm service cavity, then lime-plaster-compatible Fermacell board. Build-up 75mm total, versus 150-200mm for mineral wool plus plasterboard. Customers keep more of their living space and the wall remains breathable.

Timber frame panels in a Grade II* farmhouse

Thinnest build-up we fit — 45mm Actis Hybris Mini inside the studs with a 20mm reflective air gap, finished with lime-compatible wood-fibre board. Reversible: staples in, staples out, no glue, no expanding foam touching the original frame.

EPC uplift — what the numbers look like

Listed homes start from a low EPC baseline. A typical pre-1919 cottage comes in at band F or G. Multifoil retrofit across roof and one gable end consistently lifts to band D — a 15-25 SAP-point uplift. That band change matters for two reasons: it opens the door to GBIS funding (where eligible), and from 2028 it becomes a legal requirement for anyone letting the property (minimum EPC E for new tenancies from 2028, band C from 2030).

The planning paperwork we handle

1. Listed Building Consent application — we prepare drawings, material schedules and method statement.
2. Pre-application advice where the officer has historic concerns about the product.
3. BBA certificate copy, installer training record, and BBA-approved installation photos.
4. PAS2035 moisture-risk assessment showing dew-point stays outside critical fabric zones.
5. Post-install report with thermal imaging, confirming the as-built U-value matches design.

On a typical Grade II application we handle the paperwork in 4-6 weeks from survey to consent. Grade I and Grade II* are slower — usually 8-12 weeks — and we work with conservation consultants where the officer requests one. OMEGA carries the cost of the consultant in the initial quote, not added at the end.

What we will not install on a listed home

• Spray foam (open or closed cell) — the lending-risk and reversibility profile rules it out.
• Cavity wall fill on a solid-wall-with-render build (the cavity is usually decorative, not thermal).
• EWI on a listed exterior — alters the heritage character and almost never consented.
• PIR-only internal wall liner without a proper service cavity and VCL — wrong moisture profile.
• Any product without BBA certification — your planning officer will reject it.

Book a free listed-home survey

If you own a Grade II or Grade II* home in Essex, Suffolk, Kent or Cambridgeshire and you have been told insulation is impossible, book a free survey. We have completed 40+ listed-home jobs in the last 24 months and carry the paperwork end-to-end. Ring freephone 0800 229 4094 or book online. No cost. No obligation. No pressure.