How to Fix External Insulation Problems

As a homeowner or property manager, you know the importance of maintaining your building’s external wall insulation system. Even the best insulation can develop issues over time. Left unaddressed, these issues can lead to higher energy bills, structural damage, and costly repairs down the line.

We will discuss how you can fix external wall insulation problems to ensure your property’s external wall insulation remains in top-notch condition.

How Long Does it Take To Install External Insulation 

Before beginning repairs, it’s important to plan accordingly as the installation process can be time-consuming. For minor repairs to a small area, it may only take a day or two. 

However, for larger-scale insulation replacements around an entire home, the project timeline extends to a week or more depending on the size of the property. 

Now let’s discuss the process. . .

  1. Inspect and Identify the Issues

You need to thoroughly inspect your external wall insulation system and identify the specific problems before you can fix any issues. Here’s how:

Visual Inspection

Carefully examine the exterior walls and look for any visible damage. Pay close attention to areas around windows, doors, and all corners as these are the common spots for issues to develop.

Thermal Imaging

Use a thermal imaging camera to detect areas of heat loss which can indicate gaps or moisture problems in the insulation system. Thermal imaging can reveal issues that might not be visible to the naked eye.

Moisture Testing

Use a moisture meter to check for high moisture levels in the insulation or rendering. Excessive moisture can lead to mold growth, deterioration, and other serious problems.

  1. Prepare the Work Area

Before starting any repair work, it’s essential to prepare the work area properly:

  • Clear the area around the affected walls, removing any obstacles or debris.
  • Set up safety equipment, such as ladders, scaffolding, or lifts, to ensure safe access to the work area.
  • Gather all necessary tools and materials, such as sealants, fillers, rendering materials, and protective equipment (e.g., goggles, gloves, respirators).
  1. Address Cracks, Rendering Issues, and Moisture Problems

External wall insulation systems can develop a variety of issues over time – from cracks and gaps in the insulation itself, to problems with the protective render coating, to moisture infiltration that can wreak havoc. 

This step walks you through properly repairing all three major types of damage:

First, locate and repair any cracks or gaps in the insulation:

  1. Clean and thoroughly dry the affected area.
  1. For small cracks/gaps, apply a flexible sealant or filler according to product instructions.
  1. For larger gaps, reinforce with mesh tape before applying the sealant.

Next, tackle any issues with the rendering (the protective outer coating):

  1. Carefully remove any loose, crumbling, or detached sections of render.
  1. Prepare the exposed surface by cleaning and priming per manufacturer’s specs.
  1. Apply a new render coating, following all application and curing instructions precisely.

Finally, resolve any moisture problems, as dampness can severely compromise insulation:

  1. First, identify and eliminate the source (leaks, rising damp, condensation, etc.).
  1. Use dehumidifiers and/or heaters to completely dry out damp areas.
  1. Replace any damaged panels.
  1. Once fully dry, apply a vapor-permeable waterproof coating to prevent future moisture ingress.


Addressing external wall insulation problems can seem daunting but this guide shows you have the power to restore it to optimal condition by following the right steps. Don’t let insulation issues persist and cause bigger headaches down the road. 

The key is taking a proactive, preventative approach. Have confidence that you can handle many common insulation repairs as a diligent homeowner. Approach fixes strategically using this guide and you can restore high-performance insulation. You’ve got this!

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