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 through the treated wall (U-value: 0.725 → 0.608 W/m²K), ~28% lower heat loss than the untreated control wall, and a sustained 2–3°C increase in internal wall surface temperature. 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.

Programme length depends on property size and scope, but a typical whole-house installation is generally completed within approximately 2–3 weeks including finishing works.

Typical projects range from approximately £10,000 for a 1–2 bed flat or cottage to £35,000 for a larger period property. Full pricing by property type, what affects the cost, 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. Heat Halo is particularly relevant for solid-wall housing stock where external insulation is impractical and conventional internal boarding is too disruptive for occupied properties.

Find out more on our Housing Associations page.

Yes. Structured pilot programmes can be developed to assess installation practicality, resident impact, thermal performance and wider retrofit suitability. Learn more about our pilot approach →