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Breathable, Insulating Render & Plaster

Internal / External Wall Insulating Render

ProofTherm is an award-winning, insulating render/plaster that is ultra-breathable and made from inert natural minerals. It has been designed and formulated as a practical and affordable insulation solution that allows buildings to breathe, reducing the problems and damage caused by damp.

ProofTherm is applied as an insulating basecoat at a minimum of 20mm on external or internal walls. Up to 35mm can be applied in a single pass without slumping, and multiple layers can be built up to 100mm if and where required.

The vast majority of existing properties could benefit from better insulation. Heat loss through walls accounts for up to 33% of all domestic heat loss in UK buildings according to The Energy Savings Trust. ProofTherm very effectively increases the thermal resistance of any wall, which means it’s ability to resist temperature change by not allowing heat to pass through it.  Better insulated walls means lower heating bills in winter and a much more comfortable living environment in summer.


How does ProofTherm Work?

The insulating aggregate in ProofTherm is full of microscopic air bubbles trapped in a honeycomb like structure. Heat can’t be conducted easily through air; it’s why we now build houses with cavity walls and why we wear down-filled jackets. By creating a continuous layer of highly aerated render/plaster across a wall, we are creating millions of micro-cavities that resist the flow of heat through the structure.


How is ProofTherm applied?

ProofTherm is supplied in bags and mixed with water in a large bucket, typically using a paddle mixing attachment with a drill. It can be applied to any sound wall once the wall has been properly primed with ProofBase breathable acrylic primer. Once roughly applied, it is flattened off and left to dry before application of a protective top coat. If breathability is a key concern, the finishing coat also needs to be breathable. ProofDeco mineral render is a breathable, protective top coat that can be applied at 3mm-5mm to provide a decorative finish. Alternatively a lime based, coloured skim coat can be applied as the protective top coat.

When used internally, ProofTherm should be finished off with a lime skim coat (lime plaster) to protect it from damage.

Call us now on 01622-535009 to place your order or for more information

ProofTherm is suitable for use on external walls, internal walls and is also manufactured as a screed for insulating floors

Its primary function is to provide insulation which it achieves by combining lightweight aggregates of igneous rock that have millions of air bubbles trapped in their structure, with a traditional mineral render. The result is a lightweight render/plaster that can be applied to most walls to increase the thermal and acoustic performance of the structure.


ProofTherm is a high-performance insulating render/plaster that provides a number of benefits in one product: Thermal insulation, fire resistance and sound insulation.

When applied as an insulating base coat it helps regulate the internal temperature and moisture handling properties of the building, reducing the energy demand for heating and cooling and creating greater thermal comfort.

The vapour permeable structure of ProofTherm makes it a highly breathable solution for older properties where damp and mould problems max exist.

Essential Characteristics Performance Method of test
Thermal Conductivity λ10 dry (W/m.K) T1 (0.06 W/m.K) EN 1745:2012
Reaction to fire A1 EN ISO 1182, ISO 1716
Adhesion(N/mm2 and fracture pattern (FP)A,B or C 0.1 N/mm2 FP:B EN 1015 - 12:2000
Compressive Strength CS II EN 1015 - 11:2000/A1:2007
Capillary Water Absorption W1 (0.3 kg/m2.min⁰.⁵) EN 1015 - 18:2014
Water vapour permeability (μ) 6.27 µ EN 1015 -19:2000/A1:2006
Dry bulk density (kg/m3) 450 kg/m3 ±%10 EN 1015 -10:2001/A1:2007
Sound insulation (db) 23db (3cm/500hz) EN ISO 10140-2


ProofTherm insulating render/plaster is prepared and used in much the same way as any ready-to/use render or plaster product.

One 15kg bag of ProofTherm covers approximately 2m2 of wall when applied at a depth of 20mm and can be applied at depths ranging from 20mm up to 100mm.

Careful preparation of the surface to be insulated is, as always, very important. For optimum adhesion the wall should be free of dust, grease and any loose material and should then be prepared with ProofBase acrylic primer.

ProofTherm is primarily an insulating material and needs to be finished off with a decorative and resilient top coat such as ProofDeco mineral render.

For full instructions on how to use ProofTherm, please download our guide.

20mm of ProofTherm applied to an uninsulated brick wall will increase its Thermal Resistance by 250%

Manufactured to European Standard EN-998-1:2016


+44 1622 535009


ProofShield Ltd
Energy Works
Gas Road
United KIngdom

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