Wall insulation · UK installer
Wall insulation that cuts heat loss and stops damp — without ripping your house apart.
We install breathable sprayed cork wall insulation for solid-wall and cavity-wall homes, listed buildings, and commercial properties across London and the South East. Up to 30% better wall U-value, no scaffolding scars, no repaint cycle, 25-year warranty.
Why insulate your walls
Around 35% of a UK home's heat escapes through the walls.
Wall insulation is the single most cost-effective fabric upgrade you can make to a poorly-insulated property. With energy bills volatile and the UK pushing toward net-zero, untreated solid walls are leaking heat — and money — every winter. The right wall insulation cuts that loss, eliminates cold-bridge condensation, and lifts the EPC rating of the building.
The challenge: traditional external wall insulation (EWI) is expensive and invasive. Internal wall insulation eats room space and creates dust. Cavity wall insulation only works if you have a cavity. Sprayed cork wall insulation sits between all of those — breathable, 3–6 mm thick, externally applied, and a fraction of the cost of EWI.
Internal & external wall insulation
Two systems, one breathable material.
External wall insulation
For exterior walls of homes and commercial properties. Breathable, 3–6 mm sprayed cork bonds to brick, render, pebble-dash, timber and uPVC. No scaffolding scars, no repaint cycle, 25-year warranty.
View serviceInternal wall insulation
For cold internal walls, damp patches and condensation. Raises wall surface temperature above the dew point so condensation can't form, while staying vapour-permeable.
View serviceWhy sprayed cork for wall insulation
Breathable, fire-rated, and a third of the cost of EWI.
Cuts heat loss up to 30%
Independent U-value testing on solid walls. Most clients see a clear difference in the first winter.
Breathable, stops condensation
Vapour-permeable Class 1. Raises wall surface temperature above the dew point without trapping moisture in the brick.
Carbon-negative material
Cork bark is hand-stripped without felling. Harvested oaks store up to 5× more CO₂.
25-year warranty
Manufacturer-backed. 40+ year service life. No repainting.
How wall insulation options compare
Cavity, EWI, IWI or sprayed cork?
| System | Suits | Breathable | Indicative cost |
|---|---|---|---|
| Cavity wall insulation | Post-1920s cavity walls | Depends on fill | £400–£1,500 |
| External wall insulation (EWI) | Solid walls, max thermal upgrade | Limited | £8k–£22k |
| Internal wall insulation (IWI) | Listed exteriors, no EWI option | Limited | £5k–£15k |
| Sprayed cork (ours) | Solid & cavity, heritage, commercial | Class 1 vapour-permeable | ~⅓ cost of EWI |
Indicative ranges only. Final pricing confirmed after a free site survey.
Wall insulation FAQs
What people ask before insulating their walls.
- What is the best type of wall insulation for a UK home?
- The right wall insulation depends on your wall construction. Cavity walls (post-1920s, two skins with a gap) are usually filled with blown bead or mineral wool. Solid walls (pre-1920s single-skin brick or stone) need either external wall insulation (EWI), internal wall insulation (IWI), or a breathable thermal coating such as sprayed cork. For older solid-wall homes and heritage properties, breathable cork wall insulation is often the most appropriate option because it doesn't trap moisture in the wall fabric.
- How much does wall insulation cost in the UK?
- Cavity wall insulation typically costs £400–£1,500 for a standard 3-bed semi. External wall insulation (EWI) is £8,000–£22,000 fully installed. Internal wall insulation (IWI) is £5,000–£15,000 with all the disruption that brings. Sprayed cork wall insulation lands at roughly a third of the cost of EWI and is applied externally without scaffolding scars or disruption inside the property.
- Does wall insulation actually reduce heating bills?
- Yes. Around 35% of heat loss in an uninsulated UK home goes through the walls. Effective wall insulation can cut that loss substantially — independent testing of sprayed cork shows up to a 30% improvement in wall U-value, with most clients reporting a clear difference in the first winter and payback inside 5–8 years.
- What's the difference between internal and external wall insulation?
- External wall insulation (EWI) goes on the outside of the building — typically expanded polystyrene or mineral wool behind a render finish. Internal wall insulation (IWI) goes on the inside as insulated plasterboard, reducing room size. Sprayed cork is an external coating but it's only 3–6 mm thick, so it preserves architectural detail and doesn't need scaffolding to remain in place once installed.
- Can wall insulation cause damp?
- Poorly chosen wall insulation can — particularly non-breathable systems on solid walls, which trap moisture against the brick and cause interstitial condensation. Breathable wall insulation (such as sprayed cork) is vapour-permeable, so moisture passes through the coating rather than getting trapped. This is why cork is widely specified for listed buildings and pre-1920s solid-wall properties.
- Do I need planning permission for wall insulation?
- For most properties on standard streets, no — wall insulation is treated as a re-render or redecoration under permitted development. Listed buildings, conservation areas and flats above the ground floor will need consent. We handle the conservation officer conversation for you on those projects.