At the standard 20mm ProofTherm base coat depth, ThermoSilicone increases the R-Value (thermal resistance) of a single-skin masonry wall from 0.18 to 0.738 m2K/W — an improvement of 310%. At 30mm the improvement is 406%. At 50mm it is 597%. Source: CIBSE Guide A, Section 3.
0.058 W/mK. This compares very favourably with sand (approximately 0.5–1.5 W/mK depending on type) and cement render (approximately 0.4–1.0 W/mK).
Yes — particularly in rooms on the cold side of the property and in solid-wall properties where walls are the primary source of heat loss. The insulating layer reduces the rate at which heat escapes through the wall, so rooms reach and maintain their target temperature more efficiently.
Yes. Increasing thermal resistance works in both directions. In summer, the same insulating barrier that prevents heat escaping in winter also reduces heat gain from outside — keeping rooms cooler on hot days
Perlite is a naturally occurring volcanic mineral. When subjected to intense heat, it expands to form a lightweight material with a honeycomb microstructure of micro air-bubbles. This structure gives it excellent thermal insulation properties. ProofTherm uses expanded perlite as its primary aggregate, replacing sand in a conventional render or plaster base coat.
No. ThermoSilicone is priced at the same level as a conventional external re-render. The application process and timescale are the same. There is no premium for the thermal performance.
For internal walls we are adding a full insulating layer of ProofTherm before skimming with a regular plaster, so there is a slight price uplift compared with just skimming a wall. It is, however a fraction of the cost of insulating with XPS or EPS insulation boards
No. The survey is completely free and carries no obligation to proceed.
ThermoSilicone is a five-layer system: substrate preparation, Uni Primer, ProofTherm insulating base coat (20–25mm), ProofBond emulsion primer, and ThermoSilicone silicone finish coat. The process is carried out by Proofshield-trained installers to manufacturer specification.
ProofTherm is applied as an insulating base coat at 20mm depth. This is thicker than a conventional plaster base coat. Once cured, it is finished with a breathable skim coat of lime plaster in the same way as any plastered wall.
Where existing render is in poor condition — debonding, cracked or contaminated — it is removed before ThermoSilicone is applied. Applying over a failing substrate compromises both adhesion and thermal performance and would void the warranty.
A typical external re-render on a semi-detached property takes two to four days. Internal plastering of a room takes one to two days. We confirm the exact programme at survey stage.
If your damp is caused by condensation — warm indoor air condensing on cold wall surfaces — then yes. By raising wall surface temperatures, ThermoSilicone and ProofTherm eliminate the cold spots where condensation forms. Without condensation, mould cannot grow. This is a permanent result of improved thermal performance, not a separate damp treatment.
ThermoSilicone is an effective waterproofing system for a regular external wall above the damp course. If water is entering through failed pointing, cracked masonry or structural defects, these must be addressed before installation. We identify penetrating damp during the free survey and advise accordingly
Yes. Both systems are formulated from vapour-permeable expanded perlite and Lime, which allows moisture vapour to pass through the wall rather than accumulating. This means existing damp walls can dry out over time after installation.
The warranty covers both materials (Proofshield warrants performance to specification) and workmanship (Thermal Plastering warrants the installation standard). It is issued in writing and registered with Proofshield.
Yes. The warranty transfers to the new owner within the 15-year period.
Book a free, no-obligation survey. We will visit your property, assess your walls, and tell you exactly which Proofshield system is right for you — and what it will cost. No pressure, no hard sell.