What is External Wall Insulation (EWI)?

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External wall insulation involves fixing a layer of insulation material to the wall, then covering it with a reinforcement and a modern thin-coat render. The finish is usually a textured render, pebble-dash, brick slip or a brick effect render finish could be used.

A typical EWI System

These finishes can be used alone, or in a combination so that considerable variety in the appearance of the treated wall can be achieved.

Key Points – External Wall Insulation:

  • Can save approx. £435* per property per year (Detached house – source: Energy Savings Trust)
  • Can save approx.1.8 tonnes* of carbon dioxide per year (source: Energy Savings Trust)
  • Can be applied with minimal disruption to the household and its occupants
  • No internal access is required
  • Does not reduce the floor area (living space) of the property
  • Improves the appearance of the property – potentially increasing the property’s value
  • Improves weatherproofing and sound resistance
  • Will make the building more airtight, reducing heat loss (Need to ensure building has sufficient natural and mechanical ventilation)
  • Reduces the risk of condensation

* based on insulating a gas-heated, detached home (source: Energy Savings Trust)