What Is Lead Flashing?

When it comes to keeping your home watertight, there are a few crucial components. One of the most important ones is lead flashing, and whether you’re building an extension, replacing a roof or simply carrying out maintenance, understanding what lead flashing is and how it works is vital for any UK homeowner.

In this blog, we’ll explore what lead flashing is, its purpose and benefits as well as the various types available. If you’re planning any form of roofing project, this guide will provide you with everything you need to know.

Read on for more…

What Is Lead Flashing?

Lead flashing is a flexible, waterproof material used in building construction to prevent water from penetrating the junctions and edges of roofs. It acts as a seal between different building materials, especially around areas that are prone to water ingress, like chimneys, dormers, valleys and areas where walls meet roofs.

Made from high-quality, malleable lead sheeting, lead flashing has been used for centuries across the UK due to its excellent durability and performance in harsh weather conditions. It is traditionally applied to layers or folded over and around various elements of a roof in order to channel water away from vulnerable areas of a property.

What Is The Purpose Of Lead Flashing?

The primary purpose of lead flashing is to create a watertight seal between different parts of a building. As roofs and walls naturally expand and contract due to temperature changes and weather exposure, the flexibility of lead allows it to accommodate this movement without cracking or becoming damaged.

Without proper lead flashing, rainwater can seep through gaps in the house and cause serious problems such as:

Damp patches on walls or ceilings
Mould growth
Structural wood rot
Internal leaks and damage

By directing water safely away from joints and seams, lead flashing plays a vital role in preserving the structural integrity and comfort of your home.

What are the benefits of lead flashing?

Lead flashing remains the material of choice because it has several key advantages:

Durability: When correctly installed, lead flashing offers unrivalled longevity and can last for over 100 years.
Weather resistance: Lead flashing performs exceptionally well in the UK’s varied climate. From heavy rain to freezing frost, it can withstand all weather conditions.
Flexibility: Lead can be easily shaped and moulded to fit the desired architectural features.
Low maintenance: Once it’s been installed, lead flashing requires minimal upkeep.
Environmentally-friendly: Lead is a recyclable material and has a low carbon footprint compared to many alternatives.

These benefits make lead flashing a reliable long-term choice for homeowners looking to protect their property.

Types of lead flashing

Lead flashing is used in various parts of a building, and its type is generally defined by its location and function. Some of the most common types include:

Roof flashing
Chimney flashing
Wall flashing
Valley flashing
Apron flashing
Drip edge flashing
Sill flashing
Channel flashing
Pipe flashing
Step flashing

Understanding The Lead Code System

The lead code system is a standard classification that is used to describe the thickness and weight of lead sheet. Each code corresponds to a specific thickness, weight per square metre and recommended application. The codes begin at three and progress to eight. The higher the code, the thicker and heavier the lead sheet. Selecting the correct code ensures that the flashing performs as intended under specific loads and weather conditions.

What Is Code 3 Lead Flashing?

Code 3 lead flashing has a thickness of approximately 1.32mm and a weight of around 14.79kg per square metre. It is typically used for internal applications and areas that have minimal exposure to water, such as:

Soakers (narrow strips used under tiles)
Cladding
Small-scale repairs

Due to its lighter weight, Code 3 is not suitable for main roof flashing or areas with high water runoff.

What Is Code 4 Lead Flashing?

Code 4 lead flashing is around 1.80mm thick and weighs 20.41kg per square metre. It’s the most commonly used lead code for general roofing applications and offers a good balance between flexibility and strength. It is suitable for:

Chimney flashing
Valley gutters
Dormer windows
Apron flashing

Its increased thickness makes it more durable and capable of withstanding greater exposure to weather elements.

Why Is Choosing The Right Lead Flashing Code Important?

Using the wrong type of lead flashing can lead to serious problems, both in the short and long term. Here’s why it is important to get it right:

Durability Issues

Thinner lead, like Code 3, can fail if used in areas that require more robust protection. The weight of water or weather stress can lead to splits or tears in the flashing.

Leaks And Water Damage

Incorrect thickness may not hold up against heavy rainfall, resulting in leaks and water ingress that can cause severe damage.

Expansion

Like with many other materials, lead can expand in the heat of the day and contract at night when the temperature drops. If the wrong type of flashing has been fitted, this can cause it to buckle and split, exposing your roof to water ingress.

Aesthetic Inconsistency

Using mismatched codes can also be unsightly on the building, especially if the flashing ends up splitting or sagging.

Non-compliance With Building Regulations

For commercial buildings, regulations will often specify the type of lead flashing that needs to be used. Using the wrong type could result in a failed inspection or require costly remediation work.

Wasted Costs

Cutting corners with cheaper, thinner lead flashing may save money upfront, but will likely lead to higher maintenance or replacement costs down the line.

Final Thoughts

Overall, lead flashing is a critical component in any roofing or external wall system. It offers protection, durability and peace of mind for homeowners across the UK. From sealing chimneys to protecting roofs, this versatile material continues to stand the test of time.

So, whether you’re embarking on a DIY project or hiring a professional, always make sure your lead flashing is up to the task. For more home improvement blogs, be sure to browse our website’s range of articles.