What Is Lead Flashing and Why Does It Fail?

Lead flashing is a vital component of a roof structure, and a part that helps to protect your roof from some of the most common causes of weather damage. 

So, if you’ve spotted damp patches on your ceiling or around the chimney breast, or seen water ingress occurring near a roof window, it could be caused by failing lead flashing.

In this article, Stapleford Roofing’s team of roofing repair professionals have shared a handy guide to understanding what lead flashing does, and what causes it to fail. 

That way, you can identify and resolve these issues quickly and effectively, before they are allowed to escalate. 

What is lead flashing?

Lead flashing is a waterproof, weatherproof barrier, which is added to any point where the roof surface meets a vertical structure. 

It is designed to prevent rainwater from seeping into any vulnerable joints on the roof (the points where different parts of a property intersect), thereby adding extra weather protection.

The flashing is added in a way that creates a secure, watertight seal. It is also shaped in a way that directs rainwater away from the property itself, and onto the surface of the roof (towards the gutters). 

Typically, lead flashing is added around:

• Chimney stacks
• Roof windows and skylights
• Roof junctions and valleys
• Dormer windows
• Abutment walls

Why does lead flashing fail?

It’s important to note that lead flashing is constantly exposed to the elements, protecting the property against wind and rain all day every day. 

While lead is an extremely robust and durable material, there are some factors that mean flashing may not achieve its predicted lifespan. 

Common reasons why lead flashing can deteriorate and fail include: 

• Age – Lead flashing is designed to last for decades. But, over time, changing temperatures (causing repeated expansion and contraction) will gradually weaken the flashing. Over time, this can result in fatigue cracks.
• Thermal movement – High quality lead flashing is designed to accommodate this cycle of expansion and contraction. But, if the flashing wasn’t installed correctly, it may struggle to accommodate this movement, which can lead to the flushing raising, distorting or splitting. 
• A poor quality installation – Common issues caused by a faulty or low quality installation include incorrect lead thickness or sizing, insufficient fixing, insufficient overlaps, incorrect coverage over the roof’s features. All of these issues can result in the flushing failing early. 
• Deteriorating mortar joints – If lead flashing is dressed into brickwork or masonry, it is held in place using mortar joints. If the mortar cracks or erodes, then the joints can fail, and the flashing can come loose. 

What happens if flashing issues are ignored?

If lead flashing develops a defect, it can escalate extremely quickly. 

As the flashing is constantly exposed to the elements, water can soon penetrate the structure, causing it to develop and worsen rapidly into a much more expensive and complex problem. 

For instance, in a short space of time, lead flashing defects can develop into:

• Internal damp 
• Ceiling staining
• Damaged plasterwork
• Mould growth
• Timber decay and rot
• Extensive roofing repairs

Repair VS replacement?

It’s important to note that an issue with your flashing doesn’t always necessitate a complete replacement.

Generally speaking, if the lead itself is still in good condition, then a professional repair may be enough to resolve the issue. 

If the damage is limited to either minor movement, isolated damage or deteriorated mortar joints, then a professional may be able to repair this for you. 

However, if the lead itself developed cracks, or it has distorted or deteriorated, then it’s best to replace the flashing, before you risk more significant property damage. 

At Stapleford Roofing, our expert team can assess the condition of your flashing and the issue you’re facing, and recommend the most effective long-term solution. 

To find out more, or to arrange our professional repair services for your property, don’t hesitate to get in touch.