Internal wall insulation FAQs for solid-wall properties

Heat Halo is designed primarily for solid-wall properties where conventional insulation upgrades are impractical, too disruptive or unsuitable for the building fabric. This typically includes period, heritage and other hard-to-treat solid-wall properties.

Heat Halo may be suitable where traditional retrofit options would alter a building's appearance or internal detailing. Suitability should always be assessed on a property-by-property basis.

Find out more on our About page.

Yes. Heat Halo is designed as a professionally managed internal retrofit system that can typically be installed while properties remain occupied, depending on project scope.

Yes. Independent in-situ testing under BS EN ISO 9869 measured a reduction in wall heat loss and warmer internal wall surface temperatures compared with an untreated control wall. See the full methodology →

Heat Halo was independently tested by Build Test Solutions Ltd under BS EN ISO 9869 — the recognised standard for in-situ measurement of real-world wall thermal performance. The test recorded a 16% reduction in heat loss on the tested wall. Applied to a wall starting at the typical pre-1940 solid-wall baseline of 2.0 W/m²K, the equivalent improvement is around 25%. The test also recorded ~28% lower heat loss than the untreated control wall and a sustained 2–3°C increase in internal wall surface temperature — directly relevant to condensation and damp risk. Read the full methodology →

Traditional board-based internal wall insulation can require skirting removal, socket relocation, reveal rebuilding and significant space loss. Heat Halo provides a low-build-up professionally installed alternative designed to minimise disruption.

By increasing internal wall surface temperatures, Heat Halo significantly reduces the likelihood of condensation forming on cold solid walls. The independent BTS test recorded an average 2–3°C increase in internal wall surface temperature — directly relevant to condensation and mould risk. See how it works →

Black mould is influenced by moisture conditions, ventilation, occupancy patterns and cold surfaces. Heat Halo reduces condensation risk by warming wall surfaces, but mould risk should always be assessed as part of the wider building environment.

Poorly designed retrofit systems can create moisture risks if inappropriate materials are used or moisture movement is not properly considered. Heat Halo is designed as a vapour-permeable system for solid-wall properties.

Yes. Heat Halo is designed to remain vapour-permeable, allowing moisture movement through traditional solid-wall construction rather than trapping moisture within the wall.

Heat Halo is designed to minimise disruption compared with conventional internal insulation systems. There is no board installation, no major reduction in room size and significantly less invasive internal alteration.

Heat Halo is a millimetres-thin internal insulation system designed to avoid the significant space loss associated with traditional internal board systems.

Not in most cases. Heat Halo has been developed to avoid the extensive alterations associated with traditional internal boarding systems, though installation requirements will depend on the individual property.

It depends on the scope. For homeowners having the full property treated, installations typically range from approximately three weeks for smaller terraced homes to six weeks for larger detached properties, including all finishing works. Most homeowners remain in occupation throughout.

For social housing providers using the Cold Wall Pilot, each individual wall is a three-day installation. The property remains occupied throughout.

Terraced houses typically range from £12,000–£16,000, semi-detached homes £17,000–£22,000, and detached homes £23,000–£30,000. Optional plastering, decorating and finishing packages are available where required. Every quote is fixed after a survey. Full pricing by property type and how it compares to other options is covered in the Cost Guide →

Project costs depend on scope, but Heat Halo can be commercially attractive where the disruption, remedial work and space loss associated with conventional internal insulation are factored in. See the full cost comparison →

Mainstream grant schemes do not currently cover all specialist internal wall insulation systems, but local authority retrofit programmes and targeted funding initiatives may be available depending on property type and location. It is worth checking with your local council and any active Great British Insulation Scheme or ECO4 assessors serving your area.

Every Heat Halo installation is covered by a 10-year installation-backed system guarantee, covering defects in the installed coating system and associated plaster finish when installed by approved Heat Halo contractors and used as specified.

The guarantee covers the installation — not projected energy savings or EPC outcomes, which depend on many factors outside any single insulation measure. It applies to professionally installed work only, which is why Heat Halo is not available as a DIY product.

Yes — and particularly for addressing persistent damp, mould and condensation complaints caused by cold walls in occupied social housing. The Cold Wall Pilot is designed as a targeted, low-disruption intervention rather than a whole-house retrofit project.

The standard price is £2,995 per wall (up to 12m²), with a three-day installation programme. The property remains occupied throughout. Full details on the Social Housing page →

A targeted thermal treatment applied to cold, condensation-prone walls in occupied social housing. Heat Halo increases internal wall surface temperatures — reducing condensation risk on the walls that generate the most damp and mould complaints.

Each intervention covers one wall up to 12m², installed in three days by an accredited two-person specialist team. The property remains occupied. Your organisation completes finishing works through its existing contractors.

£2,995 per wall (up to 12m²). Typical pilot programmes are structured as:

5 walls — £14,975  ·  10 walls — £29,950  ·  20 walls — £59,900

This is the entry cost for a structured, evidenced intervention programme — significantly lower than a traditional 5-dwelling retrofit pilot.

Heat Halo is particularly suited to end-terrace gable walls, corner bedrooms, top-floor rooms, solid-wall construction, and locations with persistent condensation complaints or repeat mould — often the walls where mould repeatedly returns despite cleaning, decoration, ventilation improvements and resident engagement programmes.

Heat Halo provides a structured, evidenced cold wall intervention with full QA documentation per treated wall. This supports social housing providers in demonstrating a proactive, evidence-based response to persistent damp and mould complaints — rather than repeated reactive remediation.

The pilot programme generates thermal performance evidence, resident outcome data and QA records suitable for regulatory review and internal sign-off. Discuss the Cold Wall Pilot →

Heat Halo is designed to sit within a measured, risk-managed retrofit process with Retrofit Coordinator oversight, aligned with PAS 2035 principles — for social housing providers where this is relevant to their wider retrofit strategy.

The Cold Wall Pilot can be deployed independently of a full PAS 2035 retrofit pathway, as a targeted response to specific damp and mould complaints. It does not require social housing providers to commit to a whole-house retrofit programme to access the intervention.