Right Insulation Thickness for Solid Wall External Insulation

Insulating solid brickwork walls plays a pivotal role in enhancing energy efficiency and ensuring compliance with building regulations. Understanding the appropriate thickness of insulation required for your project is crucial to achieve the desired thermal performance. Let’s delve into the specifics to guide you through this crucial decision-making process.

Building Regulation Standards

In the UK, meeting the stipulated maximum U-value for external walls, set at 0.30W/m²K by building regulations, is essential. This U-value represents the rate of heat loss through a material; the lower the value, the better the insulation’s thermal performance.

Insulation Thickness Guidelines

Expanded Polystyrene (EPS) Insulation

Achieving the targeted U-value of 0.30W/m²K for solid brickwork walls often entails installing EPS insulation with a thickness of approximately 90mm². This thickness ensures an effective barrier against heat transfer, meeting the required standard and contributing to energy efficiency.

Mineral Wool Insulation

Alternatively, mineral wool insulation presents another viable option. To meet the building regulations’ U-value of 0.30W/m²K, approximately 110mm of mineral wool insulation is necessary. This material offers excellent thermal properties, aiding in temperature regulation within the building.

Phenolic Insulation

When opting for phenolic insulation as part of an external wall insulation system, a thinner option is available. Utilizing a 60mm thickness of phenolic insulation can achieve the sought-after U-value of 0.30W/m²K. This lightweight yet effective solution ensures compliance while minimizing the overall thickness of the insulation layer.

Factors Influencing Choice

Several factors might influence the choice of insulation besides meeting regulatory standards:

  • Space Constraints: In scenarios where space is limited, opting for a thinner yet high-performing insulation material like phenolic might be advantageous.
  • Cost Considerations: While thicker insulation may offer better thermal efficiency, it’s essential to balance performance with cost-effectiveness.
  • Environmental Impact: Some insulation materials have varying environmental impacts. Considering eco-friendly options can align with sustainability goals.

Selecting the right insulation thickness for solid brickwork walls involves a balance between regulatory compliance, performance, and practical considerations. Whether it’s EPS, mineral wool, or phenolic insulation, each material offers distinct advantages in meeting the desired U-value requirements.

Consulting with insulation experts or utilising U-value calculators specific to your project can provide tailored guidance. Ultimately, making an informed decision ensures not just compliance but also optimal energy efficiency and comfort within the built environment.

What is a U-Value?

If you are interested in energy efficiency, you may have heard of the term U-Value. But what does it mean and why is it important? In this blog post, we will explain what a U-Value is, how it is measured, and how it affects the thermal performance of your home.

A U-Value is a measure of how much heat passes through a material or a structure. It is expressed in watts per square meter per degree Kelvin (W/m2K). The lower the U-Value, the better the insulation. For example, a wall with a U-Value of 0.2 W/m2K will lose less heat than a wall with a U-Value of 0.5 W/m2K.

U-values are important for designing energy-efficient buildings, as they indicate how much heat will be lost or gained through different parts of the building envelope. By choosing materials and structures with low U-values, we can reduce the need for heating and cooling, and save money and resources.

How are U-values calculated?

U-values are calculated by dividing the rate of heat transfer through a material or a structure by the temperature difference across it. For example, if a wall has a U-value of 0.3 W/m²K, it means that for every degree of temperature difference between the inside and the outside of the wall, 0.3 watts of heat will flow through each square meter of the wall.

To calculate the U-value of a composite structure, such as a wall with multiple layers, we need to add up the thermal resistances of each layer. Thermal resistance is the inverse of thermal conductivity, which is a property of each material that describes how easily heat can pass through it. The higher the thermal conductivity, the lower the thermal resistance, and vice versa.

For example, to calculate the U-value of a cavity wall with bricks, insulation and plaster, we would do the following:

– Find the thickness and thermal conductivity of each layer
– Calculate the thermal resistance of each layer by dividing the thickness by the thermal conductivity
– Add up the thermal resistances of all layers, including the internal and external surfaces
– Find the inverse of the total thermal resistance to get the U-value

The lower the U-Value, the better the insulation.

The image shows a cross-sectional view of a wall with different layers and their respective thermal resistances labeled. The U-Value of the wall can be calculated by finding the reciprocal of the sum of all the thermal resistances of each layer, including the inner and outer faces.

The formula is:


  • U is the U-Value in W/m²K
  • Rsi is the thermal resistance of the inner face in m²K/W
  • R1, R2, R3, and R4 are the thermal resistances of the first, second, third, and fourth components of the wall in m²K/W
  • Rso is the thermal resistance of the outer face in m²K/W

To find the thermal resistance of each component, you need to know the thickness and the thermal conductivity of the material. The thermal resistance is calculated by dividing the thickness by the thermal conductivity.
For example, if the first component is a brick wall with a thickness of 0.1 m and a thermal conductivity of 0.7 W/mK, then the thermal resistance is:
R1=0.70.1=0.143 m²K/W

What is K-Rend?

K-Rend: The Ultimate Solution for Superior External Wall Finishing

Welcome to the definitive guide to K-Rend, your go-to resource for understanding the ins and outs of this revolutionary external wall finishing solution. At EZ External Wall Insulation, we’re passionate about providing you with the most comprehensive information to make informed choices for your projects.

What is K-Rend?

K-Rend is a high-quality render specially formulated for external wall applications. It’s a pre-mixed cementitious product designed to provide a durable, weather-resistant finish to buildings, offering both protection and aesthetic appeal.

K-Rend: Brand or Product?

K-Rend is a renowned brand name in the rendering industry. It’s synonymous with excellence in external rendering solutions, offering a range of innovative products designed to meet diverse construction needs.

K-Rend or K-Rendering?

The term “K-Rend” is often used interchangeably with “K-Rendering.” Both refer to the same high-performance render manufactured by the K-Rend brand.

Does K-Rend Manufacture Silicone Render?

Yes, K-Rend, the leading brand, offers a range of render solutions, including silicone render. Their silicone-based renders are known for their flexibility, water repellency, and breathability, making them ideal for various construction applications.

Does K-Rend Only Manufacture Monocouche Render?

While K-Rend is recognised for its Monocouche render, they offer a broader spectrum of rendering solutions, catering to different project requirements.

Is Silicone Render Better than Monocouche Render?

Determining the superiority between silicone render and Monocouche render depends on specific project needs. Silicone render excels in flexibility and water resistance, while Monocouche render is celebrated for its one-coat application and breathability. Each has distinct advantages, making the choice reliant on project specifics.

Is K-Rend the Same as Silicone Render?

K-Rend encompasses various types of renders, including silicone-based and Monocouche renders. Therefore, while K-Rend offers silicone render, the brand represents a broader array of rendering solutions.

Is K-Rend a Coloured Render?

Yes, K-Rend offers a wide selection of colours to suit architectural preferences and design requirements, ensuring a vibrant and lasting finish to your exteriors.

Is K-Rend Better than Silicone Render?

The superiority of K-Rend or silicone render hinges on project-specific needs and preferences. Both render types offered by K-Rend excel in different aspects, providing durability, aesthetics, and weather resistance.

In conclusion, K-Rend stands as a leading brand, offering diverse, high-quality render solutions for external wall applications. Whether you opt for the flexibility of silicone render or the ease of application with Monocouche render, K-Rend ensures excellence in both quality and performance.

For more information and to explore our range of K-Rend solutions, get in touch with E Z External Wall Insulation and Rendering today!

Multi-Coat Structural Waterproofing Render for Basements and Swimming Pools

Unseen but essential, the structural integrity of buildings depends greatly on how well they withstand the forces of nature—especially water. Among the various protective measures available, tanking emerges as a hero in ensuring the longevity and resilience of basements and swimming pools. Let’s dive into the depths of tanking, exploring its significance, application, and benefits.

Understanding Tanking

Tanking, simply put, is the process of creating a waterproof barrier within a structure to prevent water ingress. This is particularly crucial for areas like basements and swimming pools that are below ground level or in constant contact with moisture.

Multi-Coat Structural Waterproofing Render: A Game-Changer

Within the realm of tanking solutions, the multi-coat structural waterproofing render stands out as a reliable choice. Composed of specialized materials such as cementitious or polymer-based systems, this render provides a multi-layered shield against water penetration.

Application Process

The application of multi-coat render involves meticulous steps:

  1. Surface Preparation: Thorough cleaning and preparation of the substrate to ensure proper adhesion.
  2. Priming: Application of a primer to enhance bonding between the substrate and the render.
  3. Coat Application: Layering the waterproofing render in multiple coats, ensuring even coverage and adequate thickness.
  4. Curing: Allowing sufficient time for each coat to cure and achieve its maximum strength.

Benefits of Multi-Coat Tanking

The adoption of multi-coat structural waterproofing render brings forth a multitude of advantages:

Robust Waterproofing

The multiple layers provide enhanced protection, making it highly resistant to water ingress. This durability ensures long-term structural integrity.


Adaptable to various substrates, including concrete, masonry, and even existing finishes, making it a versatile solution for different structures.

Durability and Longevity

With proper application and maintenance, multi-coat tanking systems boast extended lifespans, reducing the need for frequent repairs.

Structural Reinforcement

Aside from waterproofing, these renders can also add structural strength to the surfaces they cover, contributing to the overall stability of the building.

Importance in Basements and Swimming Pools

Basements and swimming pools are vulnerable to hydrostatic pressure and constant moisture exposure due to their location. Implementing multi-coat tanking systems in these areas is crucial to prevent water seepage, structural damage, and Mould growth, ensuring a safe and habitable environment.

Tanking, especially through multi-coat structural waterproofing renders, plays a pivotal role in fortifying structures against water-induced damage. Its application in basements and swimming pools is not merely a choice but a necessity for ensuring the longevity and safety of these spaces. Investing in robust tanking solutions is not just a precaution; it’s a commitment to a secure, water-resistant future for our built environments.