Solid-wall performance report
How SprayCork performs on the UK's 8.5 million solid-wall properties.
Independent in-situ U-value, air-permeability and thermal-retention measurements from CorkSol UK's Comprehensive Analysis Report — plus a Heat3D U-value certificate on a pre-1900 solid brick wall at Church House, London.
Headline numbers
Measured, not modelled.
32%
U-value reduction
Solid brick, Heat3D test (Church House, London)
24%
U-value reduction
Solid sandstone, in-situ measurement
32%
Air permeability drop
Whole-building post-application
53%
Equivalent leakage area cut
Less uncontrolled ventilation
61.7%
Longer heat retention
TTL 1°C improvement, 1930s brick
4 kg
CO₂ offset per m²
Cork content alone (Ecobilan / PwC)
Case study · Church House, London SW1
Solid brick, pre-1900 — 1.06 → 0.72 W/m²K.
Tested by CorkSol UK using the Heat3D in-situ measurement method with a FLIR ONE Pro thermal camera. Both surveys followed identical 45-minute timelapse protocols on the same office wall, before and after a 4–6 mm SprayCork application.
Pre-application
1.06 W/m²K
U-value rating: Poor
- Internal surface temp
- 14.6 °C
- vs SAP assumed
- 38% better than SAP assumed (1.70)
Post-application
0.72 W/m²K
U-value rating: Average
- Internal surface temp
- 19.2 °C
- vs SAP assumed
- 57% better than SAP assumed (1.70)
Case study · 1930s solid brick · York
Semi-detached, brick — heat loss high → low.
Original render to front and side was insufficient; rear monocouche was cracked and discoloured. Existing render was removed, brickwork tied and primed, and SprayCork applied at 4–6 mm. The rear monocouche was sprayed over directly — no hack-off needed.
Heat-loss risk
High in all rooms → medium/low
Time-to-lose-1°C
28 min → 53 min (+61.7%)
Installation time
Few days, no scaffolding scars
Disruption
Non-invasive, no internal space lost
Case study · 1920s solid sandstone
Solid stone — U-value, air-tightness and leakage area.
| Metric | Pre-retrofit | Post-retrofit | Change |
|---|---|---|---|
| Ground-floor north U-value | 1.45 W/m²K | 1.22 W/m²K | -24% |
| Air permeability (whole house) | Baseline | Baseline -32% | -32% |
| Air permeability (front room) | Baseline | Baseline -28% | -28% |
| Equivalent leakage area | Baseline | Baseline -53% | -53% |
Why this matters
7.7 million UK solid-wall homes are still uninsulated.
Government data puts the UK solid-wall stock at 8.5 million properties — 90% uninsulated. Traditional internal wall insulation (IWI) eats internal floor space; external wall insulation (EWI) is expensive, intrusive and often refused on traditional or listed buildings. SprayCork delivers measurable U-value reductions at <6 mm thickness, with full vapour permeability and a 25-year warranty.
Lower heating demand
Up to 30% structural heat-loss reduction reported in-situ.
Better air-tightness
32% lower whole-building air permeability post-application.
Fire-rated B-s1, d0
EN 13501:2007 — suitable internally and externally up to 11 m.
Carbon-negative
≈ 4 kg CO₂ offset per m² from the cork content alone.
FAQ
Solid-wall performance, answered.
- How much does SprayCork reduce U-values on a solid brick wall?
- In an independent Heat3D in-situ test at Church House, London, a pre-1900 solid brick wall measured 1.06 W/m²K before SprayCork and 0.72 W/m²K after — a 32% reduction, with no loss of internal floor space.
- What U-value reduction was measured on solid stone?
- On the 1920s solid stone case study, the ground-floor north façade fell from 1.45 W/m²K (pre-retrofit) to 1.22 W/m²K (post-retrofit) — a 24% reduction, validated against the modelled prediction of 1.29 W/m²K.
- Does SprayCork improve air-tightness?
- Yes. Whole-building air permeability fell by 32% after application on the 1920s case study, with the equivalent leakage area dropping 53%. That means less uncontrolled ventilation and lower heating demand.
- How long does the building stay warm after the heating switches off?
- On the 1930s solid brick case study, the time-to-lose-1°C (TTL 1°C) increased from 28 minutes to 53 minutes — a 61.7% improvement in heat retention.
- What's the carbon footprint of SprayCork itself?
- Cradle-to-gate (ISO 14040, stages A1–A3): 1.09 kgCO₂eq/kg. Because cork is harvested without felling the tree, the product offsets approximately 4 kg of CO₂ for every m² installed.
- Is it suitable for traditional and listed buildings?
- Yes — SprayCork is vapour permeable to Class 1 (EN 1504-2:2005), so traditional solid walls continue to breathe. It's been used on Victorian, Edwardian, 1920s stone and 1930s brick properties across the UK.
Same wall, lower U-value, no lost space.
Tell us about your solid-wall property and we'll come back with a U-value calculation and indicative price.