Average cost to repair flashing on a roof

There are a number of different factors which will indicate the likely bill if you have defective flashing on your roof and these are:-

• Whether your roofer can re-use the existing flashing or whether you require new flashing and/or an upgrade in the type of flashing
• How easy it is to access the area that needs repair and how complex the repair is as this affects labor costs
• What metal the flashing is made from if you are buying new
• Whether there has been an ongoing leak (more about leaky roof repair) which has damaged structures underneath or adjacent to the flashing

What is flashing and why is it required?

Flashing is a thin material, usually galvanized steel, that provides a seal to direct water away from any point where the roof plane meets a vertical surface like a wall or dormer.

It is commonplace to fit flashing around root features and inserts like vents, chimneys, skylights and dormer windows to direct water away from a potentially vulnerable point towards the roof shingles where it can be channelled downwards and into the guttering instead of seeping into the roof deck. Roof features are always vulnerable to the ingress of water at these points. Without the protection of flashing, water could drip into the crevice between the wall and the roof and then make its way into the rooms below, causing mould and mildew, damp stains and potentially ruining decoration. Water will also cause slow rot in the roof deck which could even lead to collapse at a later date.

Flashing is also used for other critical roof areas including sidewalls – this is where the roof surface meets the wall – valleys, where two roof slopes meet, and roof edges which means the rakes and eaves in the roof.

According to the Federal Emergency Management Agency or FEMA, absent, damaged or incorrectly installed roof flashing around the chimney, dormer or roof cricket is near enough the most common cause of roof leaks. Flashing is not something to overlook when you are planning the spend for a roof repair or roof replacement or upgrade. Learn more about roof leak repair costs.

Different types of flashing

There are countless different types of flashing depending on the area which needs repair but here are the key types:-

• Continuous flashing – also called ‘apron’ flashing, this flashing does exactly that, acts like an apron. It is one long, single piece of metal that channels water onto the shingles and this type of flashing is prone to breaking or warping as it struggles to flex as the roof expands and contracts in different weather conditions. If you have old apron flashing, it could pay to replace it with an upgrade to flashing with built-in expansion joints which offer more flexibility
• Base flashing – some parts of the roof require two pieces of flashing, for instance, around the chimney, one of these pieces is sometimes referred to as the base flashing or apron flashing which forms the bottom piece. Two-part flashing is better able to manage the continued expansion and contraction of the roof materials than continuous flashing
• Counter flashing – this is placed opposite to base flashing
• Step flashing – this is a rectangular piece of flashing shaped with a 90-degree bend in the center and is used for roof to wall joins. Step flashing is usually installed in layers with the roof shingles to direct water away from the wall
• Skylight flashing – some skylight manufacturers will include bespoke flashing with their products whereas sometimes your roofing professional will have to purchase it or make it separately
• Valley flashing – open valleys have flashing to protect this vulnerable area of the roof
• Drip edges – the edge of the roof all the way along has thin metal flashing that helps the water drip off the roof to prevent ponding and pooling
• · Kickout flashing – the bridge between step flashing and the start of the gutter, kickout flashing directs water away from the wall and into the gutter

Buying flashing for your own roof repair

There are premade flashing pieces available for purchase but many professional roofers will cut their own pieces of flashing from sheet metal and then bend them to the exact size and shape they need. Premade flashing needs careful research as there are products available which are not designed to be used on roofs and are manufactured for door and windows – these will break if you try and install them on a roof.

How do you know if the roof flashing is failing or in poor repair?

The clearest sign that roof flashing is failing is leaks from the roof. Roof flashing when it deteriorates may cause slow water moisture leaks which over time can allow significant amounts of water to penetrate the structure of the house. Staining can appear on walls or ceilings and wood will start to rot, there could be mould or mildew growth. Paint can bubble up and there may be visible mould growth on exterior walls which were previously protected so you may notice this as a new occurrence.
The flashing itself may start to rust or move or even break loose which will be visible from the ground. Flashing can also become bent, cracked or dented and even fall off. Regular roof inspections can help you spot problems with flashing before they become serious, leading to just a minor repair with a small bill at the end of it rather than a serious and expensive problem.

What is the best and most cost-effective flashing to repair a roof?

There are different types of metal for roof flashing and the correct choice depends on the roof style, your budget and other factors like access for maintenance and rust-resistance. Here are some of the most popular metals:

• Galvanized Steel – probably the most cost-effective choice and the most durable and long-lasting as galvanized steel is resistant to rust
• Aluminium – lightweight and easy to bend, aluminium is the roofer’s choice for roofs with oddly shaped features and where the seal is awkward or tricky
• Roofing felt – not so durable, roofing felt is not usually deployed as a sole material but used in conjunction with other types of flashing as it is not waterproof. Roofing felt is often a second line of resistance to prevent water ingress
• Copper – less available, copper is a great choice with a very pleasing aesthetic when matched with copper roofing materials. Copper is malleable, sturdy and resistant
• Rubber – rubber is flammable so houses at high risk of fire should best avoid it, it is also not durable although it is flexible but ironically, does not always provide the most efficient watertight seal
• Plastic – PVC is a good and cost-conscious choice, it is long-lasting and durable, however it cannot be matched with asphalt roof shingles
• Galvanized steel is the most common choice as a roof flashing but discuss with your roofer if you think another material may be a better choice.

Do roof flashing products come with any guarantee or warranty?

They do and it is usually one year although some products will offer a longer guarantee often as long as twenty years. A year is not as long as the warranty offered for the other roofing materials that make up your roof and this is because of the varied life of different roofs and potential adverse weather conditions. Flashing must be correctly and properly installed otherwise any warranty will be void.