Thru-Wall Flashing is Essential: The Hidden Guardian to Protect Your Building from Water Intrusion

Water intrusion impacts your building’s integrity, tenant satisfaction, and bottom line. While the exterior facade may appear sound, hidden weaknesses—like failing or improperly installed thru-wall flashing—can quietly cause significant problems. Protecting what’s behind the wall(s) is essential to keeping your property dry, secure, and well-maintained.

What Is Thru-Wall Flashing and Why Does It Matter?

Thru-wall flashing is a key component of drainage plane wall systems (sometimes called cavity walls). It works behind the exterior surface to direct water from the building before it can penetrate interior spaces.

When appropriately installed, thru-wall flashing:

  • Redirects water that seeps behind the facade away from openings like windows, doors, and roof edges.
  • Prevents leaks that damage conditioned spaces, tenant areas, and structural components.
  • Preserves building integrity, protecting your investment from long-term moisture-related issues like mold, corrosion, or concrete spalling.

However, when thru-wall flashing is missing, damaged, or improperly installed, water can bypass this critical barrier, resulting in hidden damage that grows more severe (and expensive) over time.

The Hidden Costs of Failing Thru-Wall Flashing

If water infiltrates a drainage plane wall, fixing the issue requires more than surface repairs—it requires getting to the root cause. This often involves temporarily removing the exterior facade (brick, stone, or panels) to inspect and repair the weather-resistant barrier (WRB) and flashing system.

Proper thru-wall flashing repairs include:

  • Rubber and Metal Flashings: Essential for channeling water out of the wall system.
  • End Dams: Prevent water from running off the flashing edges and into the building.
  • Weep Holes: Allow trapped water to drain out of the system safely.

Without these components, water can pool behind your walls, leading to severe structural and interior damage—often hidden until it’s too late.

This is a remedial thru-wall flashing assembly being installed; however, there are no end dams visible as it is a continuous shelf-angle flashing.

Visualize It

To better understand how thru-wall flashing integrates into the overall drainage plane system, we’ve included a detailed visual example below. This graphic, created by IMI, demonstrates the layers of protection behind the cladding and highlights key elements such as flashings and end dams.

This masonry window head detail illustrates continuous air, moisture, and vapor resistance with integrated transition materials, insulation for thermal control, cavity drainage protection, and thru-wall flashing with end dams and drip edges for moisture management. While the backup wall shown is a concrete masonry unit (CMU), it could also be constructed with materials like metal studs and sheathing. Firestop material may be added per code.

Proactive Repairs: Your Best Defense Against Water Damage

Many water intrusion issues stem from construction shortcuts or aging systems where key elements, like end dams, were overlooked. These oversights result in recurring leaks, tenant complaints, and escalating repair costs.

Proactive thru-wall flashing inspections and repairs allow you to:

  • Identify vulnerabilities early, before leaks disrupt tenants or impact your budget.
  • Extend the life of your building’s wall system, reducing the need for costly emergency repairs.
  • Prevent hidden damage, ensuring moisture is effectively managed and directed out of the wall system.

How PIERCE Helps You Take Control

At PIERCE, we help property managers protect their buildings by identifying the underlying causes of water intrusion and providing targeted, practical solutions. With our expertise and LIFECYCLE360 technology, we:

  • Identify Your Wall System: We determine whether your building uses a barrier or drainage plane wall and pinpoint vulnerabilities.
  • Inspect for Hidden Issues: We uncover problems like failed flashings, missing end dams, or compromised weather-resistant barriers.
  • Provide Proactive Repairs: Our solutions address the root cause of water intrusion, not just the surface symptoms.
  • Offer Actionable Insights: Through detailed reporting, we help you prioritize repairs and plan for maintenance budgets.

Keep Water Where It Belongs: Outside Your Building

Thru-wall flashing might be hidden behind your walls, but its role in protecting your building is critical. By partnering with PIERCE, you gain a team that understands your building’s unique needs and works to protect it for years to come.

Don’t let hidden water issues spiral into costly problems. Schedule an inspection with PIERCE today to protect your building and bottom line. 

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