Cornerstone Insulating Render

Render, Insulation and Dehumidifier all in one. Lightweight render which offers low strength, high flexibility, high vapour permeability and advanced thermal performance, for use on solid walled masonry.

Insulating Render has been specifically designed to reduce heat loss in solid walls and older buildings. Working as a lightweight base coat for rendering and plastering applications, Insulating Render offers significantly improved insulation and moisture management, as well as much faster application times compared to conventional lime renders.

Key Benefits

  • Work Quicker, Apply Thicker – Insulating Render can be applied up to 30mm depth as a single coat, compared to standard lime mortar which is 15mm per coat, significantly reducing labour times and costs.
  • Let Your Walls Breathe – behaves the same as a standard NHL2 render, offering a highly vapour permeable and highly flexible coating, helping reduce issues such as damp and decay
  • Highly Insulating – with a measured K Value of 0.12, a 25mm coat will improve the U Value of a solid wall by around 40%, whereas a 50mm coat will improve the U Value by around 60%.
  • A Dehumidifier for Your Walls – by incorporating non-porous aggregate Insulating Render helps to regulate moisture movement through the wall and reduce cold spots. Independent testing verifies how Insulating Render can absorb, store and buffer excess moisture, releasing it when suitable and never trapping it within the wall, improving the air quality and comfort of internal spaces.
  • Superior Performance – Insulating Render is at least 50% more insulating than the closest performing market alternative and is priced to meet or cost less than market alternatives.
  • Space Is A Premium – Insulating Render can be applied directly the wall it does not require framing or boards which can reduce space. If you are looking to maximise insulation it can also be incorporated within a boarded system.
  • Natural Mineral Ingredients – made using only NHL2, recycled aggregates and additives enabling it to be used on virtually any background and contains no organic content so no fear of the coating rotting or breaking down.


£12.75 Ex VAT. (£15.30 Inc VAT.)

5% discount on orders over £500 (Excluding Vat & Delivery). For larger projects visit our pricing page.

SKU: 212301.
9 kg
Categories: , . Manufacturer:
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Cornerstone Insulating Render is designed to improve the thermal performance of solid walled masonry, whilst maintaining the high vapour permeability and low strength of an NHL2 render. Insulating Render offers a viable solution for Part L1B legislation in that it meets the requirements for improving the thermal performance of a wall, whilst maintaining a permeable fabric which absorbs and readily allows for the evaporation of moisture and will not prejudice the character of the host building or increase the risk of long-term deterioration of the building fabric or fittings. With a measured K Value of 0.12, Insulating Render significantly outperforms similar systems both in terms of performance and cost. A 50mm application will improve the U value of a solid wall by 50% or more, significantly reducing heat loss.

Most available lightweight/insulating materials use aggregates that have a two-dimensional structure, when these are subject to pressure during application the aggregate can breakdown, reducing both the thermal performance and durability of the mortar. Cornerstone Insulating Render uses a specialist recycled ultra-lightweight hardened aggregate with a three-dimensional structure, which does not breakdown under application and improves both the durability and insulating properties of the render.

Fibre additions improve the flexural strength of the render, distributing stresses across the render to help reduce point loading, and negate the need for any mesh to be applied to the wall or inserted within the render

Insulating Render can also be used in sustainable construction projects as a basecoat onto natural building materials such as hemp, straw and rammed earth. The insulating properties help reduce the thermal expansion differentials between the background and any subsequent coatings.

Area of Use

Ideal for use internally on properties with solid wall construction.

Used In Conjunction With

Insulating Render can be used as a base coat, for internal plaster like finishes we would advise using Cornish Lime CLM66 fine putty plaster and for external finer finishes we would recommend using Cornerstone Promix fine NHL2.

  • Cornish Lime Fine Putty Mortar Bag
    Fine Putty Mortars
    Natural lime mortars with fine sands for pointing, fine renders and plastering.
  • Cornerstone Promix
    Professional grade, multipurpose lime mortars and renders for Pointing and Render applications.


For internal applications it can be applied as backing coat or through to finish coat, or finished with a lime plaster. For external applications, apply as a backing coat with Cornerstone Promix fine NHL2 as a finish.

Suitable for application onto most host surfaces. If working on weak/friable backgrounds such as cob, please contact us for further application information.

After mixing, a bag will produce approximately 13.8 litres of mortar. For quantity purposes, assume that for every 10mm depth, you would need 0.72 bags per square meter.

Please read the Cornerstone Insulating Render DataSheet for full application information.

Each project is unique, always seek professional advice before undertaking a project.

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