The problem

Most insulation was not designed for heritage buildings.

Pre-1919 buildings were designed to breathe. Lime mortar, solid brick and stone absorb and release moisture as part of a natural cycle. Seal that wall with modern insulation and you trap moisture inside the structure.

  1. 01

    Moisture trapped

    PIR boards create cold bridges and vapour barriers. Moisture condenses inside the wall, invisibly damaging the historic fabric.

  2. 02

    Wet walls waste heat

    Wet walls conduct heat up to 3× faster than dry ones. Insulation that causes dampness can worsen energy performance over time.

  3. 03

    Bulky systems wreck proportions

    Thick build-ups alter window reveals and room proportions, the features that define a Georgian or Victorian building. BreatheTherm achieves excellence in as little as 25mm.

See the BreatheTherm solution

Our approach

Insulation that works with your walls, not against them.

BreatheTherm breathable insulation is specifically formulated for pre-1919 and listed buildings. Our systems use natural vapour-permeable materials (including perlite and aerogel) that maintain the balance your walls depend on.

Moisture is always present: rain, ground moisture, occupancy. The aim is not to block it, but to manage its movement safely.

  1. 01

    Moisture moves freely

    Vapour-permeable materials allow moisture to pass through rather than accumulate at the insulation boundary.

  2. 02

    Walls self-regulate

    Hygroscopic products absorb peak moisture and release it gradually, smoothing humidity spikes inside the building and within the wall.

  3. 03

    Building fabric lasts longer

    No interstitial condensation means no timber decay, masonry spalling, failed renders or mould growth.

  4. 04

    Thermal performance improves

    Dry walls insulate better. As moisture balances, heat loss reduces and efficiency genuinely improves.

  • Energy efficiency
  • Breathability
  • Heritage friendly
  • Sustainability
  • Compatibility
  • Comfort & well-being

Retrofit without regret

What changes in the wall.

The cheapest insulation is not always the lowest cost option. In traditional buildings, moisture risk, failed detailing and fabric damage can turn a quick fix into an expensive problem.

Designed to keep heat in, let moisture out, and protect the building for the long term.

Conventional BreatheTherm

Moisture

Moisture safety Higher risk in solid wall buildings Designed to manage moisture safely
Breathability Typically sealed systems Fully vapour-open
Long-term performance Can degrade if damp develops Stable, moisture resilient
Remedial risk Risk of corrective works if issues arise Significantly reduced risk

Heritage fit

Listed building suitability Often difficult to obtain consent Typically more acceptable
Build-up thickness Often requires thick layers Slim, space-saving build-up
Property value impact Risk of issues arising at survey Long-term quality increases valuation

Doing it once

Upfront cost Lower Moderate–higher
Installer complexity Multiple systems and detailing required Simple, integrated system

Explore every layer

External walls

Floor

PerliTherm

17th-century Cotswold farmhouse