Bay Window Roof Replacement Cost

Looking into the cost of a Bay Window roof in 2026?

Bay windows have been a popular feature in terraced and semi-detached houses since the Victorian era and through to the 1920s and 1930s.

They add floor space and extra natural light to the interior and better views of the exterior. Bay window roofs are flat or pitched and are covered using lead, fibreglass, EPDM rubber, tiles or felt.

If your bay window roof is leaking or looking a little dated or shabby, it may be time to consider a replacement.

Although a bay window roof is a small roof job, it is vitally important that it’s done properly to prevent water penetration, withstand high winds and last for many years.

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How Much Is Bay Window Roof Replacement?

The average cost of a bay window roof replacement is between £350 and £2,350, depending on the size of the window bay, the roofing materials and the condition of the structure underneath the roof covering.

Small, straightforward replacement bay window covering will usually be at the lower end of the scale, while larger bay windows, or bays that curve or have ornate detail, will cost more.

Replacing the bay window roof on a small bay window can cost between £350 and £730. A medium bay window replacement with no other work necessary can cost between £450 and £1,700. A large, straightforward bay window roof replacement can cost between £550 and £2,200.

These costs can increase if other work needs to be done, such as repairing or replacing the timber deck or renewing fascias or soffits.

Bay Window Roof Replacement Prices

Here are the average costs of bay window roof materials per m², using 1 or 2 days as the amount of time it normally takes to complete the job.

Average costs of a bay window roof installation according to roof material, including labour at an average of £250 a day, apart from lead and slate installers, who typically charge on average around £350 (in London and the South-East of England, labour may cost more).

Bay Window Roof Replacement Cost

Installation will take longer if there are other repairs to carry out, such as replacing rotten decking or improving insulation. In these cases, the roofing contractor may charge per m² or by the hour for work that doesn’t take up a full day. The average roofer’s rate per m² is between £30 and £60.

Typical additional work on a Bay window roof includes:

Supply Costs of Bay Window Roof Replacement

There are a number of supplies required to replace a bay window roof. The cost of supplies depends on the size of the bay and the type of roof. Overall costs will increase if you include premium materials, or leadwork and/or decorative detailing.

The main materials that may be needed include:

• The roofing cover, premium materials are lead and slate tiles, which cost between £95 and £275 per m²
• Battens - £6-£20 or can be purchased in packs.
• Timber decking - £14-£25 depending on size
• Plywood or OSB boards - £24-£35 depending on size
• Membranes - £9-£14 per m²
• Flashings - £6-£18 depending on size
• Gutter trims - £7-£20 depending on size
• Fixings - £9-£11 per pack
• Sealants - £3.50-£9.00 (300ml)
• Replacement fascias or soffits, if needed, £12-£40 depending on size

Additional Costs of Bay Window Roof Replacement

When you budget for a replacement bay window roof, it is always a good idea to think about the additional costs that might come up as a result of the work. For example, once the roof covering has been removed, you might find the decking has rotted or is sagging, insulation needs improving, or you need to fix areas where there is water damage.

Other additional costs include waste disposal if they are not included in the quote, skip hire and scaffolding if the roof is at height. You might also need to replace soffits, facias or guttering. Being aware of additional costs will help you to work out your budget more efficiently and avoid any unexpected expenses once the work is in process.

Labour Costs and Timescales for Bay Window Roof Replacement

Labour costs account for a good proportion of a bay window roof replacement. Generally, the work can be carried out by a roofing specialist who typically charges between £200 and £275 a day.

However, carpenters or general builders with experience in bay window roofing installation may also offer this service at around the same price as a roofing contractor.

If you are having a lead or slate bay window roof installed, then roofers who are specialists in working with lead and/or slate will likely charge a higher daily rate of around £350 a day, which reflects their expertise.

Labour rates in London and the South-East of England will be higher than in other parts of the UK.

Cost Factors for Bay Window Roof Replacement

There are several factors that influence the overall cost of a replacement bay window roof. The main consideration is the size and shape of the bay and whether it is curved or ornate, which will require more experienced workmanship.

The roof material will also have an effect on the final price. If you are on a budget, then felt is an affordable option. If you have a lead roof and you want to replace it with lead again, then you will be paying for a premium material and higher labour costs due to the specialists’ skills needed for installation.

Other factors include:

• Amount of timber repair
• Whether extra insulation is applied
• The need for scaffolding
• Complexity of flashing work
• Whether roofing materials need to match the rest of the property
• Ease of access
• Whether internal damage caused by leaks needs to be repaired
• Regional labour rates

One of the most important things is to deal with any underlying issues. If these are ignored to save money, the roof covering won’t last its lifespan, and you may end up spending even more on repairs and another bay window roof replacement.

Building Regulations for Bay Window Roof Replacement

In most cases, replacing a bay window roof covering will not require building regulations approval, especially if the material being replaced is the same and there are no alterations to the structure.

However, building control will need to be informed if structural work is involved. Checking with your local authority’s building control department before you start any work is best if you aren’t sure.

Types of Bay Window Roof

Many householders choose to replace their bay window roof covering with like-for-like material. But you can change the roof covering if you prefer the appearance of another material, or you need to match the covering to your budget. Common bay window roof coverings include:

Felt

Felt is one of the cheaper materials and is popular as a covering for flat roofs. It is durable, but it has a shorter lifespan than other types of material. Installation is usually straightforward, as felt can be shaped into any awkward angles.

Cost: £50-£80 per m²

Lifespan: 15-20 years

Lead

Lead was the traditional covering for bay window roofs. They can last a lifetime, and they look beautiful. Lead isn’t cheap, and it may also be difficult to insure because it is now a target for thieves who sell lead for scrap.

Cost: £140-£250

Lifespan: 50-100 years

Slate Tiled

Slate is the traditional tile used for a bay window roof. It is strong and durable, easily withstanding UK weather conditions, and it is also very attractive. However, it is complex to fit, so you will need an expert installer, and the cost of the slate is high.

Cost: £95-£275 per m²

Lifespan: 80-150 years

Fibreglass

Fibreglass is becoming the modern alternative to lead as a bay window roof covering. It is extremely durable, and it can be installed in various designs and colours.

Cost: £120-£180 per m²

Lifespan: 35-50 years

EPDM Rubber Roofing

EPDM rubber roofing is often used on flat roofs. It is highly waterproof and low-maintenance. But it doesn’t have the aesthetic appeal of other roofing materials.

Cost: £80-£100 per m²

Lifespan: 25-35 years

You can also change the shape of the roof. It can be pitched or flat.

Pitched Bay Window Roof

Pitched roofs are usually found on period homes and traditional builds. They are often covered with slate tiles or lead. Pitched roofs tend to deal with water drainage better than flat roofs and offer a longer lifespan.

Cost: £95-£275 per m²

Lifespan: 80-150 years

Flat Bay Window Roof

Flat bay windows are cheaper to install than pitched roofs, and often you can use less expensive materials like felt, fibreglass or EPDM rubber as a roof covering.

Cost: £70-£125 per m²

Lifespan: 15 to 30 years

Alternative Types of Roof Replacement

Other jobs similar to a bay window roof replacement are often as affordable and include:

The costs depend on the size of the roof replacement and the type of material being used. Felt and EPDM rubber are the most cost-effective, and lead and fibreglass are the most expensive.

Hiring Contractors Checklist for Bay Window Roof Replacement

When you post your bay window roof replacement project on MyJobQuote, you will get at least 3 quotes from local roofing specialists in your area. Although it is tempting to go for the cheapest quote, make sure you compare each one to check what is and isn’t included. A cheap quote can often lead to additional costs once the work has begun.

Before hiring a roofing contractor, consider using the following checklist:

• Does the contractor have experience replacing bay window roofs?
• Are they specialists in slate or lead roofs (if required)
• Do they have samples of previous work and feedback from satisfied customers?
• Is waste removal included in the quote?
• Can they provide a separate quote to give you an idea of what costs would be if new decking or insulation needs to be installed?
• How much would new fascias and soffits cost?
• Is scaffolding included (if required)
• Do they have up-to-date public liability insurance?
• Is the work guaranteed?

Also, make sure the quote is in writing and covers the complete scope of the work as well as pricing for materials and labour.

Removing an Existing Roof

Before a new roof is installed, the old roof covering will be removed. The process is usually as follows:

• Strip back the original roofing cover or remove the lead or tiles
• Check the timber underneath for damage. If the decking is damaged, it will need to be removed and replaced or repaired.
• Check insulation and improve if necessary
• Lay new roofing material and ensure all joints are watertight.

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