Flashing is an essential part of any roofing system. As the first line of defence protecting your business or home from the elements, your roof needs to be in top condition to provide the level of security required. Installed correctly, flashing is essential in preventing the intrusion of water, perhaps the most damaging of all the elements.

Flashing explained

Flashing is thin pieces of impervious material designed to prevent the passage of water into a structure from a joint or other potential entry position. It works to protect at points such as skylights, chimneys, dormers or vents. It is a critical part of any roofing system, particularly where water is prone to penetration.

In the past, before sheet products became readily available, carpenters would have to be creative in order to minimise the penetration of water and moisture. Often they would angle roof shingles away from the joint or place features like chimneys at the ridge.


A wide range of materials have been, and are still, used for flashing. At some points in the past Birch Bark has been used for flashing but most popular materials include metal, plastic, rubber or impregnated paper.

Metal materials include the likes of lead, aluminium, copper, stainless steel or a metal treated with a coating. When using metal for flashing, expansion joints on long runs should be used to ensure that sheets do not become deformed due to expansion and contraction. Other roof materials shouldn’t be allowed to stain metal flashing or react chemically to it.

Flashing material can also be flexible and such elements such as rubberised asphalt, butyl rubber and acrylic are employed. Flexible flashing is not designed to remain exposed however and should be kept concealed.

Environmental concerns mean that the use of lead for flashing may be limited, but the flexibility and durability of the material make it an excellent choice for the job. Modern materials may provide adequate protection for up to 20 years whereas lead is likely to last in excess of 500 years!

Make sure flashing is fitted properly

Whilst the correct installation of flashing provides essential protection at edges, valleys and joints in your roof, poor or badly fitted flashing could lead to premature deterioration in the areas it’s designed to strengthen. So, whether it’s a new roof or just a repair or upgrade to an existing structure it’s important to make sure that installation is done correctly and professionally from the outset. Effective flashing can be one of the best things you can do to protect any property investment.

If you need a reliable roofing company and you are in London or surrounding boroughs then look no further than All Seasons Industrial Roofing Ltd. We have years of experience, superior quality control, a dedicated team and we also offer excellent prices. We are members of the National Roofing Contractors Association; one of the construction industry’s oldest trade associations

We pride ourselves on being highly recommended by our customers for providing a quality and affordable service on all our types of roofing.

For friendly advice and a FREE estimate or quote call now on 020 8938 3498