Cornerstone Insulating Render

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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. Available in a 9kg bag.

£15.55 £18.66 inc VAT

SKU: 212301 Category: Brand: Cornerstone

In stock


Cornerstone 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.

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.

As with any natural product, variations in colour, texture and shape may occur. In addition, images may vary slightly from actual products due to these natural variations and screen resolution. For the best consistency, ensure to acquire a sufficient amount of material with your order to avoid batch-to-batch variation.

  • 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.

Ideal for use internally on properties with solid wall construction.

For internal applications, it can be applied as backing coat or through to finish coat, or finished with a lime plaster. For internal finishes we recommend a our Cornish Lime CLM66 Fine Putty Plaster. Browse our range of Fine Putty Mortars.

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 cover roughly 1.4m2 to 1.5m2 at 10mm.

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

See the Technical Data and Documentation section for more detailed product information, application guidance and datasheets. Always read the available datasheets and guidance before use. Each project is unique; always seek professional advice before undertaking a project.

When working with lime, an alkaline material, always ensure you wear the appropriate PPE. Browse our range of tools and PPE to get started.

Pallet orders with Palletforce Economy are typically dispatched from Cornish Lime within 1-2 business days, providing your item is in stock and not made-to-order. Once dispatched, Palletforce will deliver your order within 3-5 business days, depending on your location. Please ensure that your site can accommodate articulated lorries or similar-sized vehicles.

Local Delivery
The Cornish Lime team provides local delivery with a 12-tonne vehicle with a crane to assist with unloading. You will be contacted by phone to arrange delivery and ensure your site can accommodate our vehicle.

APC Parcel Courier
Orders shipped by APC parcel courier are typically shipped the next business day and arrive within 2-3 business days, providing your item is in stock and not made-to-order. APC will contact you via email with delivery information, and orders can be tracked on the APC website.

Premium or Expedited Service
For a premium or expedited delivery service, please get in touch to discuss if this option is available for your order.

For further information, see our delivery information page.


  1. 5 out of 5

    Fantastic fast curing product!
    Great to work with building thickness!
    Verified Review


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