Insulation Imbalance

Insulation imbalance occurs when a building or structure has unevenly distributed insulation, leading to a variety of issues including thermal bridging, condensation, and potential mould growth. This imbalance can occur around various parts of the building such as eaves, reveals, loft spaces, chimney breasts, and flooring. Here we delve into the scientific details and implications of insulation imbalance within buildings.

Key Areas of Concern

Eaves and Reveals

Eaves and reveals are typical areas where insulation imbalance occurs, often due to inadequate or improperly installed insulation. This can lead to thermal bridging, where heat is transferred through the less insulated parts of the building, causing energy loss and potentially leading to condensation issues.

Loft Insulation

Poorly laid loft insulation can cause significant heat loss, especially during colder months. This not only leads to higher energy bills but can also result in condensation and mould growth in the loft space.

Chimney Breasts

Chimney breasts can be areas of insulation imbalance when cold or warm air enters the void, particularly in older buildings with single brick skins. This can lead to thermal inefficiency and condensation issues within the chimney breast.


Floors, particularly those in contact with the ground or over unheated spaces, can suffer from insulation imbalance if not properly insulated. This can lead to cold floors, thermal bridging, and in humid environments, condensation and mould growth.

The Science of Condensation and Mould Growth

In a humid environment, the poorly insulated zones within a building are prone to condensation as the low temperature in these areas increases the relative humidity. Mould thrives in high humidity conditions and will grow where relative humidity remains high for extended periods.

Thermal Bridging

Thermal bridging is a common result of insulation imbalance, where heat is transferred at a higher rate through the less insulated or non-insulated parts of the building. This not only leads to increased energy consumption but also a higher likelihood of condensation which can, in turn, lead to mould growth.

Relative Humidity and Mould Growth

Mould requires moisture to grow, and high relative humidity provides the perfect environment. When the temperature drops in poorly insulated areas, the relative humidity increases, creating conducive conditions for mould growth. Persistent mould can lead to structural damage over time and poses health risks to the occupants.

Addressing Insulation Imbalance

  • Proper Installation: Ensuring that insulation is properly installed in all areas of the building, paying particular attention to traditionally problematic areas like eaves, reveals, and lofts.
  • Regular Inspections: Conducting regular inspections to identify any areas of insulation imbalance early on, before they lead to more significant issues like mould growth.
  • Professional Assessment: Engaging professionals to assess and rectify insulation imbalances, particularly in older buildings or those with a history of condensation or mould issues.


Insulation imbalance is a prevalent issue that can lead to thermal bridging, increased energy consumption, and in humid environments, condensation and mould growth. By understanding the key areas of concern and the science behind condensation and mould growth, homeowners and property managers can take proactive steps to address insulation imbalance, improving the energy efficiency and overall comfort and safety of the building.

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