Roof Flashing Done Wrong: What It Looks Like and Why It Causes Problems

When roof flashing is installed incorrectly, it creates vulnerabilities that affect the performance of the entire roof. Flashing is a crucial part of any roofing system, designed to direct water away from joints and transition points. It is typically installed around chimneys, skylights, roof valleys, and anywhere the roof meets a vertical surface.

Even small errors in flashing installation can lead to serious water ingress. Poorly seated flashing, exposed fasteners, and incorrectly lapped joints are all common issues. When these faults occur, rainwater can find its way under roofing materials and into the structure below. A professional roof inspection can identify these problems early, and a roof condition report can assist with repairs or contractor accountability.

What Flashing Is Designed to Do

Roof flashing plays a simple but essential role. It acts as a moisture barrier that keeps water from entering your roof at its most vulnerable points. The materials used are usually sheet metals like aluminium or galvanized steel, which are shaped and installed to direct water toward drainage points.

In a well-installed system, flashing is tucked beneath or layered over roofing materials in a way that maintains the natural water flow of the roof. The goal is to keep rainwater moving downward and outward rather than allowing it to pool or seep inward. When installed correctly, flashing prevents water from entering spaces around chimneys, vents, skylights, and roof edges.

Problems arise when flashing is cut too short, installed without proper sealing, or simply left exposed to the elements. These mistakes reduce the effectiveness of the roof and can lead to major damage if not addressed quickly.

Roof Flashing Done Wrong: What It Looks Like and Why It Causes Problems

Signs Your Roof Flashing May Be Poorly Installed

Flashing faults are not always visible from the ground, especially if you’re not sure what to look for. However, there are a number of warning signs that often point to poor workmanship or premature failure after recent roofing work.

Visible gaps or lifting edges: Flashing that is lifting or sitting away from the surface of the roof is a clear sign of incorrect installation. It should lie flat and form a tight seal with adjacent materials.
Exposed nail heads or fasteners: Nail heads used to fix flashing in place should be covered. If they are visible, they can rust over time and create direct paths for water ingress.
Misaligned seams or sloppy overlaps: Flashing should be installed with clean, watertight overlaps. Misalignment or lack of proper lapping creates weak points where water can penetrate.
Staining or rust around flashing areas: Discolouration or signs of rust around flashing can indicate that water is already breaching the surface and pooling behind the metal.
Leaks that appear during or after rain: If you notice water entering around skylights, chimneys, or internal ceiling junctions, the flashing in those areas may be compromised.

All of these signs should be taken seriously. What may appear to be a minor oversight can quickly become a major issue if water begins entering the roof structure.

Why Flashing Failures Lead to Water Damage

When flashing fails, it disrupts the entire waterproofing system of the roof. Water may begin seeping beneath tiles or metal panels, soaking the insulation or rotting the timber beneath. These types of slow leaks are often difficult to detect until staining, mould, or ceiling damage becomes visible inside the building.

On metal roofing systems, water entering at flashing points can cause corrosion to spread from fasteners or seams. In tiled roofs, water may soften battens or cause tiles to shift as the underlying support deteriorates. The structural logic of the roof depends on all components working together, and flashing is a key part of that system.

A professional roof inspection will highlight both the obvious and subtle impacts of faulty flashing. In many cases, we find that a problem begins with a flashing issue and eventually compromises multiple parts of the roof over time.

What We Check During a Roof Inspection

If you suspect your flashing has been installed incorrectly, a detailed roof inspection is the most effective way to assess the problem. Inspections are designed to identify faults that are not visible from the ground and to document the full extent of the issue for future action.

Placement and layering: Inspectors evaluate whether flashing has been positioned in line with best practices. This includes checking that it is layered in the correct order with tiles or metal sheeting.
Sealing and adhesion: We look for signs that flashing has been properly sealed where necessary, and that adhesive or sealant is intact and compatible with the surrounding materials.
Fastening methods: Poor fastening is a major cause of flashing failure. We assess the type, spacing, and coverage of nails or screws to ensure secure installation.
Material condition: Some flashing fails due to material faults or incompatibility. We identify any corrosion, brittleness, or bending that might affect performance.
Flow pattern and drainage: Inspectors assess whether water is being properly redirected away from joints. Improper angles or obstructions often cause water to collect near flashing points.

Each of these factors is documented in a detailed roof condition report. This report becomes a vital reference for repair work, warranty discussions, or insurance claims where workmanship is under question.

What to Do When Flashing Has Been Poorly Installed

If your roof inspection confirms that flashing has been installed incorrectly, it is essential to act before further damage occurs. Small flashing faults can usually be repaired in isolation, but larger issues or systemic installation errors may require replacement of entire flashing sections or removal of roofing material to access the fault.

For property owners who recently had roofing work completed, the first step is to check if the job is under warranty. A roof condition report is an important tool to present to the original contractor or builder. It clearly outlines the problem and provides evidence that the issue resulted from poor workmanship.

If no warranty applies or the original installer is unavailable, we can recommend the best course of action based on the condition of the roof. Whether a small targeted repair or a more significant restoration is required, it is always better to address flashing issues early, before water damage spreads to internal structures.

Book a Roof Inspection with a Focus on Flashing Issues

Flashing is one of the most common failure points on roofs we inspect across South-East Queensland. If you have had work done recently or are concerned about water ingress, a roof inspection focused on flashing can give you the answers you need.

We provide detailed roof condition reports that outline current faults, highlight risks, and help you take the next step: whether that involves requesting a repair, seeking insurance compensation, or simply gaining peace of mind about your roof’s condition. If you are concerned about the state of your roofs flashing, give Roof Inspection Reports a call on 0418 677 524 or you can click here to contact us online.

Frequently Asked Questions

Flashing should last at least 20 years when installed properly, but poor workmanship can cause early failure in under five years.

No. In many cases, flashing faults are hidden beneath roofing materials or only show signs during heavy rain. A professional inspection is needed to confirm.

Sometimes, but not always. If the flashing is under layers of tile or sheet metal, those areas may need to be lifted to perform a proper repair.

Yes. A roof condition report provides documented evidence of poor workmanship and is often used when requesting warranty-backed repairs or refunds.

Flashing is commonly used around chimneys, skylights, valleys, roof penetrations, and where the roof meets vertical walls or parapets.