Flat Roof Replacement Cost in London | 2025 Prices, Materials & Quotes

Flat roofs are found in modern and older buildings in London, most often on home extensions, garages and front porches. They're cost-effective and can provide space for solar panels or a balcony on a home extension.

Age, weather conditions and wear and tear mean there’s a high demand in London for replacements and repairs to flat roofs.

In this guide, we’ll tell you what the flat roof replacement in London costs, with any additional costs you’ll need to consider and how to find a flat roof specialist.

The Average Cost of Flat Roof Replacement in London

Generally, local flat roof specialists' prices in London are between 10% and 20% higher than in most other parts of the UK. The total amount you can spend on a flat roof replacement will depend on the type of material you use, the complexity of the job and the size of the flat roof.

Average costs and typical costs for flat roof replacement in London are higher than in other regions, and roof costs can vary based on material, size, and complexity.

Here are some examples of roofs of different sizes to make it easier to compare costs. These illustrations include materials and labour. Roofers usually work in pairs so that you will pay each roofer an hourly or daily rate. In London, this is around £38 to £44 an hour or £275 to £355 per day.

Hiring a qualified roofing contractor or roofing contractors is important for ensuring quality and compliance.

Costs by Flat Roof Material

When considering a flat roof replacement in London, there is a wide range of flat roofing materials to choose from, including traditional felt roofing, modern rubber flat roofs (such as EPDM), GRP fibreglass, and even premium options like lead for certain applications.

The choice of roofing material or flat roofing material, whether it’s cost-effective felt roofing, quick-to-install rubber flat roofs, or high-end lead, can significantly affect the overall cost, durability, and suitability for different property types, including heritage and conservation projects.

Here’s a table giving you an at-a-glance comparison of the cost of the materials for a flat roof per m²L

London Flat Roof Prices

Flat Roof Replacement Cost in London: Material and Labour

Understanding the flat roof cost and the costs involved in a flat roof replacement is essential for effective budgeting. Here are some example flat roof costs for different roof sizes:

• Double garage (30m²): Between £780 and £1,350
• Extension Roof (40m²): Between £860 and £1,565
• Front Porch (3m²): Between £275 and £655
• Lead roof on bay window (3m²): Between £875 and £955
• Flat roof on modern home (80m²): Between £2,275 and £3,235

When planning a flat roof replacement, it’s important to consider a full cost breakdown. This includes the cost of materials, flat roof replacement labour, waste disposal fees for removing old roofing materials, and roof removal itself.

Labour costs can vary, but hiring a qualified roofer or flat roofer is recommended, as professional roofers ensure the work meets required standards and regulations.

If you are having your flat roof replaced, additional costs such as gutter cleaning or minor repair costs may apply. Flat roof replacements and roof replacements in London often require careful planning to manage all associated costs.

The cheapest material for a flat roof is felt, which costs between £35 and £45 per m². The most expensive is lead, which is often used on bay windows and costs around £134-£142 per m². A green roof, fibreglass and rubber fall between the two at £38 to £150 per m².

Material only rates:

Prices for Felt, EPDM rubber, Fibreglass and a green roof (lead only included in bay window prices) would be:

• Double garage (30m²): Between £170 and £440
• Extension Roof (45m²): Between £253 and £653
• Front Porch (3m²): Between £20 and £300
• Lead roof on a bay window (3m²): £600
• Flat Roof on modern home (80m²): Between £450 and £1,108

Labour costs at London rates:

• Double garage (30m²): 2 to 3 days will cost between £608 and £912
• Extension Roof (40m²): 2 to 3 days will cost between £608 and £912
• Front Porch (3m²): 1 day will cost between £275 and £355
• Lead roof on a bay window: 1 day will cost between £275 and £355
• Flat Roof on modern home (80m²: 6 to 7 days will cost between £1,824 and £2,128

Additional Costs to Consider

• Roof Insulation – £7 and £15 per m²
• Scaffolding hire – Average cost £890 - £1,040 per week
• Waste removal/Skip hire – Around £220
• Roof windows/Skylights – Between £755 and £3,470
• Emergency work/Same day callouts – On average in London around £250
• Insulation upgrades – May not be included in standard quotes, so be sure to factor this in when budgeting for a flat roof replacement.

Neglecting timely replacement or repairs can result in more costly repairs down the line, especially if underlying damage or sealing issues are missed.

Cost saving tips for flat roof replacement in London:

• Compare multiple quotes from reputable contractors
• Choose materials that balance durability and cost
• Schedule work during off-peak seasons to potentially get better rates

Factors Affecting the Cost of Replacing a Flat Roof in London

There are a number of factors that will affect the total cost of replacing a flat roof in London, and they include:

• The size of the roof – Materials are sold by square metre (m²) 
• The type of material: For example, Felt costs between £50 and £80 per m², whereas fibreglass costs between £90 and £150 per m². The choice of flat roofing material or roofing material will impact the overall cost, durability, and suitability for different roofing systems, including those used on commercial buildings.
• Complexity and scaffolding - The average cost of scaffolding all around a semi-detached home will cost around £890 to £1,040 per week
• Removal and disposal costs of the old roof – Removing the existing flat roof or existing roof is a key step in the replacement process. If your quote doesn’t include the disposal of the old roof, you might need to hire a skip. Expect to pay around £220 for skip hire. 
• Insulation to comply with building regulations – Between £7 and £15 per m². Upgrading insulation can improve thermal performance and energy efficiency, which is essential for habitable spaces.
• Labour rates in inner London and outer boroughs – Between £300 and £350 a day. Inner London rates will be at the higher end of the scale, and roof costs in the South East, including London, are typically higher than in other regions. 

Insulation to Comply with Building Regulations

A professional flat roof installer will be aware of the building regulations for insulation and will either include this in your quote or provide a separate quote, depending on the type of insulation you want to install. Insulation is required unless the roof covers an unheated building, such as a detached garage.

Your building can have a cold roof or a warm roof, but to meet building regulations, it must have a U-value of 0.18 W/m²K.

A cold flat roof has the insulation placed inside between the roof joists. Although it is less expensive to install, it must have adequate ventilation to prevent moisture build-up and condensation.

A warm flat roof has the insulation beneath the waterproof layer on the outside of the roof, which means it is more energy efficient because there is minimal heat loss, and it doesn’t need ventilation.

Upgrading to a warm roof system with external insulation significantly improves thermal performance, helping to meet building regulations and enhance energy efficiency.

How Long Does a Flat Roof Replacement Take?

The length of time to install a flat roof does depend on the size of the roof, whether or not it needs scaffolding and the complexity of the job. Weather can also have a bearing on the completion date, as wet weather can affect drying times and labour schedules.

Rubber flat roofs are often quicker to install than other materials, making them a popular choice for fast flat roof replacements. Hiring professional roofers ensures the project is completed efficiently and to a high standard. But on average, most jobs will take a professional London roofer around 2 to 3 days to complete.

Flat Roof Lifespan and When to Replace

Typical Lifespans for flat roofs are:

• Felt: 10-30 years
• EPDM: 25-30 years
• Fibreglass (GRP): 20-30 years
• Lead: 100 years plus
• Green Roofing: 30-50 years

You might want to consider a flat roof replacement if there are cracks or tears in the material, you notice water pooling on the roof’s surface, or there are leaks when it rains.

If flat roof repair is no longer effective due to extensive leaks or structural damage, a full flat roof replacement may be necessary. Delaying the decision to replace a flat roof can lead to more severe structural damage and higher costs in the long run.

Finding a Roof Specialist in London

Hiring a professional roofer means you don’t have to worry about building regulations, safety and finding the time to get the job done. Always get at least 3 quotes if you can for a flat roof installation, so that you can compare each quote and pick the one that suits you best.

For the best results, consider hiring professional roofers with experience in flat roof replacements.

The easiest way to find a flat roof installer in London is to use MyJobQuote. Simply post your job on our website and you’ll be matched with local tradespeople.

Replacing a flat roof in London is an investment that will prevent costly water damage that could ruin treasured possessions or expensive furnishings. Posting a job on MyJobQuote ensures you can find trusted local roofers to compare quotes easily.