What Happens if Water Gets Behind External Wall Insulation?

External wall insulation (EWI) is a highly effective way to improve the energy efficiency and thermal comfort of buildings. However, when water finds its way behind this insulation, it can lead to serious structural, aesthetic, and safety concerns. In this article, we’ll explore the causes and consequences of water intrusion in EWI systems and provide actionable solutions to prevent and address these issues, especially in Dublin, Ireland’s damp and unpredictable climate.

Types of External Wall Insulation

The most common EWI systems include:

• Exterior Insulation and Finish System (EIFS): A lightweight synthetic cladding combining insulation and a reinforced finish.
• External Brick Effect Insulation: Provides an authentic brick appearance while improving insulation.
• Weatherproof Panels: Designed for durability in variable climates, these panels provide both protection and insulation.

These systems are tailored to suit specific building requirements and environmental conditions, making professional installation by an external wall insulation company in Dublin crucial.

Mechanisms of Water Intrusion

Barrier vs. Drainage Systems

The mechanism of water intrusion often depends on the type of EWI system installed. Early EIFS systems had a barrier design, which relied entirely on external seals to resist water. Unfortunately, even small breaches in these seals allowed water to penetrate and accumulate behind the insulation. In response, modern drainage EIFS systems, introduced in the mid-1990s, incorporated water-resistive barriers (WRBs) and flashings to manage water flow more effectively.

Condensation and Entrapped Moisture

Water can also enter EWI systems through condensation. In vapor-permeable walls with insufficient insulation, temperature differences between indoors and outdoors cause moisture to form, gradually accumulating within wall assemblies. This issue is compounded by thermal bridging, where structural components that are poor insulators create cold spots, further encouraging condensation.

Consequences of Water Intrusion

Moisture-Related Damage

Water behind external wall insulation can lead to costly and extensive damage. This includes:

• Loss of insulation effectiveness, reducing energy savings.
• Structural deterioration and weakening of external walls.
• Mold growth, which poses health risks such as respiratory issues.
• Delamination or detachment of the insulation cladding.

Impact on Exterior Sheathing

If moisture remains trapped, exterior sheathing materials like paper-faced gypsum can degrade over time. Biological growth like mold or algae can develop, damaging the sheathing and leading to potential structural hazards.

Adhesive and Fastener Failure

Moisture infiltration can corrode the adhesives and fasteners securing the EWI. Over time, this may cause the insulation panels to loosen or detach completely, especially during strong winds or storms common to Dublin’s climate.

Statistics and Risk Levels

High-Risk Moisture Content

Research highlights that wall sheathing with moisture levels exceeding 20% are prone to decay, while levels above 28% indicate an urgent need for remediation. Incorporating proper flashing and drainage systems during installation can drastically reduce these risks.

Flood and Water Event Risks

Dublin properties in low-lying or flood-prone areas face additional threats. A house within a “100-year” floodplain has a 26% chance of experiencing flooding during a 30-year mortgage period. Such events often accelerate water intrusion in EWI systems, creating long-term challenges.

Preventive Measures and Solutions

Incorporate Flashing and WRB

Ensure all systems include water-resistive barriers and well-designed flashing at every joint or opening. These measures act as the first line of defence against leaks and prevent water from seeping behind the EWI.

Maintain Proper Ventilation

Ventilation prevents condensation-related issues within wall cavities. Vapour permeability in EWI systems must be balanced to allow trapped moisture to escape effectively.

Regular Inspections and Maintenance

Scheduling consistent checks can identify minor issues before they escalate. Fixing small cracks or sealant failures can prevent major damage to the building envelope.

For all your external wall insulation needs, consult an experienced home insulation company in Dublin.

Future Considerations and Climate Change

In Dublin’s ever-changing weather conditions, climate change has already begun to influence rainfall patterns. Flash floods and prolonged rainy seasons increase the likelihood of EWI-related water damages. Additionally, rising sea levels may lead to more frequent flooding in coastal communities, necessitating robust, future-proof building designs.

Take Control of EWI Issues Today

Water intrusion behind external wall insulation can be a silent yet devastating issue. By understanding its causes, investing in proper installation, and embracing preventive measures, homeowners can ensure the longevity of their insulation systems.

If you’re in Dublin and worried about your EWI’s condition, contact us at Osber Insulation today. Share your thoughts in the comments below, subscribe for more practical advice, or get started on protecting your home today!