Is 50mm External Insulation Enough for Effective Home Insulation?

People often wonder if 50mm external insulation is sufficient for effective home insulation. This question arises from a desire to optimise energy efficiency while balancing cost considerations. 

In this article. We will discuss what works well for keeping homes cosy. 

Understanding External Insulation

External solid wall insulation or EWI is a process where an insulating material is applied to the exterior walls of a building. This layer acts as a barrier that prevents heat from escaping in the winter and keeps the interior cool during the summer.

How Thick Should Exterior Insulation Be

50mm external insulation is a common thickness but its effectiveness can vary depending on 

several factors. Let’s explore these factors in detail:

Factors Affecting the Effectiveness of 50mm External Insulation

  1. Building materials: Brick and concrete walls may require thicker insulation to achieve optimal thermal performance. On the other hand, timber-framed buildings may be better suited for 50mm insulation due to their inherent insulation properties.
  1. Climate and weather conditions: In colder regions or areas with extreme temperatures, 50mm insulation may not provide sufficient insulation. Milder climates, however, may find 50mm insulation more suitable.
  1. Insulation material type: Rigid foam boards typically have a higher insulation value per millimetre than mineral wool. The insulation material’s thermal conductivity plays a role in its effectiveness.
  1. Building age and construction methods: Older buildings with poor existing insulation may benefit from thicker external insulation. Modern construction techniques and building regulations often require thicker insulation levels.

As you can see, the effectiveness of 50mm external insulation is influenced by a complex interplay of elements. It’s crucial to carefully evaluate these about your specific property and location. 


Insulating your home is a critical investment in energy efficiency, comfort, and long-term cost savings. 50mm external insulation can provide a reasonable level of insulation but thicker 100mm or more may be recommended for optimal thermal performance and energy savings.

Remember that insulation is not a one-size-fits-all solution. Consult with insulation experts, energy assessors, and experienced contractors for better insights and guidance. They can assess your unique situation and recommend the appropriate insulation thickness and materials to maximise energy efficiency and long-term benefits.

Don’t settle for suboptimal insulation solutions. You can create a home that not only meets your immediate needs but also stands the test of time with the right insulation strategy.

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