Lead Flashing: Should You Flash the Cash for it?

What is Lead Flashing? 

Lead flashing is a thin, flexible sheet of lead that is used to cover joints and seams in a roof. Typically used in areas where two roof surfaces meet, such as around chimneys or dormer windows. Lead flashing is available in different sizes and thicknesses, depending on the application. Due to its malleability and unrivalled waterproofing properties lead flashing is perfect for roofing jobs such as flat roofing/pitched roofing, dormers, chimney flashing and more. Fully sustainable and environmentally friendly, lead roof flashing is 100% recyclable with a life expectancy of over 100 years!  

What is Lead Flashing Used For? 

Lead flashing is used to prevent water from seeping into your home through the roof. When two roof surfaces meet, there is a gap between them that needs to be covered and sealed to prevent water from entering the home. Lead flashing is the ideal material for this job because it's highly flexible and malleable, meaning it is easy to work with and can be bent and shaped to fit any angle or contour on the roof. It's also non-corrosive and extremely durable and long-lasting, so it will protect your home from water damage for many years.  

Why is Lead Flashing Important? 

Lead flashing is an important element of any well-built roof because it protects your home from water damage. Water can be incredibly destructive to your home, causing mould, rot, and structural harm. From rotting wood, concrete degradation, insulation damage and more, water damage can lead to costly repair fees that preventative measures will avoid. By sealing the gaps between roof surfaces with lead flashing, you can stop water from seeping into your home and causing these types of problems. 

In addition to preventing water damage, lead flashing also helps to maintain the structural integrity of your roof. Without flashing, the joints and seams in your roof would be exposed to the elements, which can cause them to weaken and deteriorate over time. By covering these areas with lead flashing, you can protect your roof from damage and extend its lifespan, keep your home dry and safe for your family. 

Lead Codes 

A lead code indicates the thickness and therefore the weight of the lead and will help determine the uses for which that lead will be appropriate.  


Code                    Nominal thickness         lbs per sq foot       Kg/m2 

Code 3 lead        1.32mm                                  3                        14.98 

Code 4 lead        1.80mm                                  4                        20.41 

Code 5 lead        2.24mm                                  5                        25.40 

Code 6 lead        2.65mm                                  6                        30.07 

Code 7 lead       3.15mm                                   7                        35.72 

Code 8 lead       3.55mm                                   8                        40.26 

Code 3 Lead 

Code 3 lead flashing is typically 1.32mm in thickness and is used in most standard roofing applications. Perfect for pitches below 15 degrees, the flexibility and malleability of code 3 lead flashing means that it can be moulded around chimneys and dormer windows with ease.  Versatile and durable, lead flashing is a material that is essential for ensuring a watertight and secure seal around awkward angles and gaps. 

Code 4 Lead 

Code 4 lead flashing is typically 1.80mm in thickness and is used in more heavy duty and ‘high risk’ applications than Code 3 lead. Perfect for pitches above 15 degrees, this thicker lead, though more expensive than Code 3, is typically used where there is more need for the strength and durability of the lead on the roof and where that extra support and thickness is required to cover the gap for waterproofing protection and where there are challenging weather conditions and heavier roof.  

Code 5 Lead 

Code 5 lead flashing is typically 2.24mm in thickness and is used for vertical cladding as well as in roofing applications where there is a heavier rainfall and more severe wind speed aimed at the roof. Also used in historical restoration projects where the importance of maintaining specialist historical features is high. This thick lead is strong and durable and ensure a high level of waterproofing and protection and resistance and ensures the risk of deformation under heavy loads is greatly reduced. More expensive than both Code 3 and Code 4 lead, Code 5 lead is used when it is essential for the longevity and structural integrity of a building's roof and walls, particularly in areas with challenging weather conditions or high loads.  

Code 6 Lead 

Code 6 lead flashing is typically 2.65mm in thickness and is used when the need for utmost strength and durability is required. Historical restoration projects as well as roofing projects and vertical cladding projects where a heavy load will be involved. Extreme weather conditions and areas with high rainfall, this lead will benefit the roof greatly. A high level of waterproofing but with high cost. The thickness of this lead makes it a lot harder to work with due to its denser and heavier construction but once applied it will stand the test of time.  

Code 7 Lead 

Code 7 lead flashing is typically 3.15mm in thickness, and like Code 6 lead is used for projects where strength and durability is desired. Used for projects where a roof with a heavy load is expected or a vertical cladding project that has the potential where impact could be an issue, also where extreme rainfall and other weather conditions are an issue then this lead code is one of the best to use. The waterproofing level, once this lead has been worked and ready to use is extreme. A high-level of longevity and reliability comes with the higher lead code. 

Code 8 Lead 

Code 8 lead flashing is typically 3.55mm in thickness and is the thickest and heaviest lead available in the construction industry. Used for extreme-duty and high-risk projects, this lead has the highest level of water penetration resistance level. It is strong and durable and can bear heavy loads and impact. Withstanding harsh chemicals and extreme weather conditions, perfect for industrial as well as commercial properties and historical restorations, this is the most expensive of the lead flashings but the. Specialist tools and expertise may be required to use this thickness of lead as it is not as easy to work with as other lead codes due to its lack of malleability.  


Lead flashing needs at least a 100-150mm overlap for effective protection against water penetration. The overlap ensure that the water runs down the surface of the flashing and away from the joint. The amount of overlap needed will depend on the lead code used. 

Safety Precautions 

It is essential to note that lead flashing installation requires proper safety precautions and should only be performed by trained professionals to avoid exposure to toxic lead dust.  All our lead sheeting is competitively priced, and we offer a nationwide delivery service, if you need some advice on what lead roof flashing you require, please get in touch with our customer service team. 

Choose your Lead Flashing with Roofing Supplies UK 

Roofing Supplies UK is an expert retailer of lead flashing products. We can advise on the right option for your needs, to ensure your roofing project is a success. We have a range of Lead Flashing  available to suit a wide variety of roofing needs. 

Are you interested in choosing your lead roof flashing today? Email us at sales@roofingsuppliesuk.co.uk, call us at 01752 466151, or order online 24 hours a day, seven days a week. We’ll be able to help you purchase your lead flashing now.