Chimney flashing repair cost

What is flashing?

Roofers are often asked this all-important question because most people recognise that broken tiles are an issue, but they don’t realise that damaged flashing can also prove to be a costly problem.

Flashing is the construction technique of installing a watertight sheet on a domestic or commercial roof to cover any joins and ensure they are sealed to prevent any leaks, damp or mould.

The average cost of replacing lead flashing on a chimney is £350 – 500, but you’ll need a budget of around £700 – 1,000 if scaffolding is required (as is often the case).

Flashing is typically made from metals such as stainless steel, copper and aluminium as these materials allow for long-lasting durability and minimal water corrosion.

Although the metal sheets used are hard-wearing and durable, they do degrade over time. Any damaged sheets will need replacing once they start showing wear and tear.

How much does lead flashing cost?

The cost of labour for lead roof flashing installation is around £20 – 40 per hour, depending on the complexity of the installation and the location of the property. Additional charges for material will apply.

Lead flashing is used wherever roofs meet walls and windows, as well as its use on chimneys.

Often, when insulation seems to be failing in a home, it is due to an issue with the flashing no longer providing a tight secure bond.

Rust and corrosion from water damage can cause the lead apron flashing to degrade. Having this checked all over your roof (particularly if you are experiencing draughts or damp and mould) is recommended.

Top tip: Whilst you are employing a roofer to repair your chimney flashing, you may want to consider having other areas of flashing examined and replaced if needed around the rest of your roof.

Whole roof flashing cost

The average approximate cost of materials for replacing lead flashing throughout a whole roof will range between £80 – 140 per m². The cost will be marginally higher if your roof is pitched.

As well as the lead flashing material, you will also need to consider the cost of other materials to complete the job, such as sealant and nails.

Sealant can cost between £5 and £10 per tube.

Fixings like nails or screws can cost between £1 and £5 per pack.

Any nails or additional fixings should have the same water-proof properties as the flashing itself, providing you with a reliable, durable seal.

Roofers generally operate in pairs and will usually charge in the region of £200 – £300 per day for labour.

Most standard flashing jobs will be completed within a single day and in many cases potentially only half a day will be required, thus reducing costs further.

Why is well-maintained flashing important?

These are the main reasons well maintained flashing is important:

• Prevents water damage
• Prevents structural damage
• Stops the development of mould and mildew due to damp
• Provides increased energy efficiency

Failure of chimney flashing can cause damage to your roof and loft space.

If you notice any signs of roof deterioration you should contact a roofing company right away to prevent any damage to the structural integrity of your chimney or roof.

Poorly performing flashing can cause significant water damage.

What can affect chimney flashing repair costs?

Location

Put simply, you can expect to pay more for your labour and material costs if you live in London and the South East compared to the rest of the UK.

Size of your chimney

The estimated cost for lead chimney flashings is £150 – 200 for supply and £100 – 250 per day for labour, the larger the chimney, the more time and materials required to complete the job so the price will potentially be higher.

Ease of access

The average cost of hiring scaffolding in the UK is between £60 – 150 per day, and most chimney flashing jobs will be completed within one day.

If your chimney flashing does not require scaffolding to access it, costs will be considerably cheaper. Most heights-related works will require the use of scaffolding to ensure safety and you will have to factor this cost into your overall budget

You will have to take into account the additional days for the scaffolding to be erected and then taken down.

Top tip! Consider hiring your scaffolding for a longer period of time and having any other work completed that requires the use of it, such as gutter cleaning or other roof maintenance.

Thickness of flashing

You can expect to pay between £25 – 70 for a three-meter roll of flashing, depending on the thickness required.

Lead flashing is available in a range of thicknesses and the cost of the chimney flashing rises accordingly.

The thicker the lead, the more expensive it will be.

The thickness of lead flashing required for your roof varies depending on the weather conditions of your property, and it is very important to ensure that the correct thickness is used for your job.

Installing flashing of an incorrect thickness or using too large a sheet of lead for a smaller space can lead to watertight failure and problems further along the line.

Lead codes range from 3 to 8, with each code representing a specific weight in kilograms per square meter. Thickness options can be discussed with your roofer.

Can I install my own chimney flashing?

You could attempt to install your own chimney flashing by buying your materials and watching a few DIY guides, but we would certainly advise against it.

Understandably, chimney flashing installation requires specialist equipment and skills and any job that requires access to a roof can be dangerous, using the right safety equipment is vital.

The cost of chimney flashing may feel higher when compared to just doing it yourself, but it is actually much more cost-effective when done correctly, compared to the cost of dealing with a damp, mouldy or leaking chimney or roof due to a bodged DIY job.

To kick your project off, post a job to get a free, no-obligation quote from a local roofer today.