How Much Does Flat Roof Replacement Cost?

Irvin Cramer

By Irvin Cramer

Last Updated on November, 2024

Want to replace a flat roof? Well, you’re in luck because flat roofs are the most affordable type for replacement. But things can still get pretty costly.

These flat roofs can cost thousands of pounds based on the type of materials used and the size of the roof. But in most cases, it’s around £7,000 to £8,000.

These replacement costs depend on various factors, and in this guide, we’ll have a detailed look at each of these factors and how they influence the flat roof cost.

So continue reading till the end, our comprehensive guide on how much does it cost to replace a flat roof. 

Quick Summary

  • The cost of replacing a flat roof can vary greatly depending on materials used, size of the roof, and other factors such as location, permits, and labor costs.
  • The average cost of replacing a flat roof ranges from £7,000 to £8,000, but can be as high as £15,000 for larger roofs or as low as £2,500 for smaller roofs.
  • It is recommended to hire a professional roofing company for flat roof replacement rather than attempting to do it yourself, as it can result in dangerous and expensive issues if not done properly.

Average Flat Roof Cost of Replacement

a roofer preparing for flat roof installation

The final cost of flat roof replacement, on average, can be around £7,000 to £8,000. At the higher end of the spectrum, the average costs can go up to approximately £15,000 to £16,000. And on the lower end of the spectrum, it can be around £2,500 to £3,500.

These rates can vary depending on a range of different factors. The types of materials used in the flat roof construction location, type of roof, size, application technique, labour, permits, etc all have a significant role to play here. 

Flat Roof Replacement Cost By Size

When it comes to size, flat roof replacement cost is based on square metres. It means that with a larger roof, you’ll need to pay more. You might pay around £4 to £20 per square metre for the replacement.

For instance, if the size of your roof is 500 square metres, the flat roof replacement cost for your flat roof will be around £1,200 to £5,500. 

Replacement for a roof that is a thousand square metres in size will cost around £2,500 to £11,000. The replacement of a 2000 square metres flat roof will be around £5,000 to £23,000. 

Useful guides:

Replacement Cost of Flat Roofs By Material

Flat roofs are available in a variety of materials. While metal roofs usually cost the most, if you’re looking for an affordable option, fibreglass roofing is your best bet.

Metal

a picture of a modern house with metal roofs

A new flat roof made of metal will cost around £4 to £30 per metre square. Although metal is the most expensive option of all flat roof materials, it’s also one of the most durable choices. Metal can withstand extreme weather conditions, such as strong winds or hail storms. 

BUR (Built-Up Roofing)

This roofing is also known as gravel and tar roofing, and a new flat roof made of BUR will cost around £4 to £10 per metre square, excluding flat roof repair activities. 

There are several layers in this roofing type, and these layers are made of bitumen and other reinforcing fabrics. 

These materials develop to make a finished membrane that can protect from physical damage or deterioration caused by sun and water. You can also opt for a felt roof which will further add to the costs. 

Rubber Membrane

This type of roofing is commonly made of ethylene-propylene-diene-terpolymer (EDPM). A new flat roof featuring a rubber membrane will cost around £4 to £14 per metre square, excluding flat roof repair activities. 

Rubber flat roofs are pretty durable and can last up to 50 years while withstanding extreme weather conditions. 

GRP (Glass Reinforced Polyester)

GRP is a corrosion-resistant, long-lasting fibreglass that can be sculpted into various irregular and complex shapes. 

Therefore, this fibreglass roof is commonly used for aesthetic and industrial applications. This material is among the more affordable options as a new flat roof featuring GRP will cost around £3 to £6 per metre square, excluding a flat roof repair cost. 

TPO (Thermoplastic Polyolefin)

Thermoplastic polyolefin is a lightweight synthetic material. This flat roof requires very low maintenance as well. Not only that, this material is resistant to water and durable. 

Hence, it is commonly used for commercial buildings and a new flat roof with TPO will cost around £3 to £13 a metre square.

Modified Bitumen

two professionals working on a flat roof installation for a building

Modified bitumen is another affordable option for a low flat roof cost. A new flat roof with modified bitumen can cost around £3 to £7 per metre square.

It goes well with conventional asphalt roofing featuring polymer modifiers for better flexibility, temperature resistance, and longevity. 

Polyurethane 

A new flat roof featuring polyurethane will cost from £3 to £6 for each metre square and is applied using a liquid mixture spray on the roof.

This spray expands and turns into a rigid foam that continues to sit across the entire existing roof substrate. As polyurethane is continuous, it can prove to be an excellent option for water resistance. Apart from that, it is highly durable, lightweight, and offers excellent insulation. 

PVC (Polyvinyl Chloride)

PVC is a kind of single ply flat roof membrane that is fire, water, and impact-resistant. 

These single ply flat roofs are mostly light or white and are highly cost-effective in reflecting sunlight and reducing cooling expenses. The PVC flat roofing material can cost around £3 to £6 per metre square. 

Concrete

These roofs can either come in the form of poured concrete or tiles. These tiles are exceptionally strong and are resistant to fire. Concrete flat roof costs can range from £3 to £7 a metre square. 

Factors Influencing the Flat Roof Replacement Costs

As mentioned previously, several factors, including application method and roof type, contribute to the final flat roof replacement cost. Let’s take a deep dive and discuss all the factors in more detail.

Roof Type

types of roofs

There are various kinds of flat roofs, suitable for different needs. Therefore, determining the cost of your roof type and matching it with your budget is important. 

Green

With vegetation and roof covering, green roofs can improve your roof’s overall drainage along with boosting the ecosystem in the vicinity. Green flat roof cost can be around £8 to £32 per metre square including the flat roofs covered. 

Tapered

Tapered flat roof cost can be around £6 to £9 per metre square and these roofs feature a slope along with an insulation that can vary in thickness. It boosts water drainage and doesn’t allow water to pool. 

Curved

These flat roofs require around £7 to £13 per metre square and they come with an arched surface that looks aesthetically beautiful and can assist in drainage. 

Hybrid

a building with newly renovated falt roof sealing

Hybrid flat roofs are a combo of warm and cold roofs and we’ll talk about both these types of flat roofs in a bit. Hybrid roofs also have layers of insulation above and below the roof deck and these roofs can cost around £4 to £10 per metre square. 

Warm

This flat roof comes with insulation at the top of the deck and it keeps the deck as well as the space under it at a steady temperature. Warm flat roof installation and replacement can cost around £5 to £11 per metre square.

Cold

A cold flat roof comes with insulation under the deck as well as within the rafters and joints. The space above is all insulated and that’s why the cost per metre square of these roofs can be around £2 to £8. 

Inverted

These roofs feature the insulation layer above the waterproof layer. In most cases, these roofs come with liquid membrane waterproofing that can protect against temperature fluctuations and extreme weather. Inverted flat roof cost can range from £3 to £8 per metre square. 

Location

Sometimes, location can also directly influence the replacement cost of your old flat roof with a new roof. For example, areas with high costs of living have higher roof repair costs than areas with lower costs of living. 

If you live in an area with extreme weather, it can make replacement and installation more dangerous and complex. Therefore, the overall replacement cost will increase for your new roof. 

Sealants

The sealants used in the installation process can also increase the overall cost. Sealants provide an additional waterproofing layer, and they can significantly boost your roof’s overall strength and durability. 

With increased durability and strength, the overall maintenance cost for your flat roof can be reduced. Prices of sealants can range from £350 to £2,000 based on the application methods and type of sealant for your flat roof installed. 

Flat Roofing Application Methods

a roofer working on the flat roof covering

Various roof types feature different materials, and they require separate application methods. Some of these methods can be more time-consuming and complex. 

For example, for some roofs fastened attachment techniques are used which can cost around £2 to £4 per metre square including labour costs. 

Ballasted roofs can cost £1 to £2 per metre square for labour, and adhered roofs can cost £2 to £3 per metre square. 

Drainage & Ventilation

Adequate ventilation prevents any moisture buildup and drainage can safeguard your entire home from any damage caused by water. Both these aspects are critical when it comes to the overall integrity of a flat roof. 

If you want to add more gutters or drains, you can expect to pay around £350 to £700, and installing a single roof vent will cost around £250 to £500. Of course, gutter cleaning costs will increase with that. 

Permits

There are times when you need a permit to replace your roof. These permits can range from £70 to £400 and even more for larger roofs. Qualified roofers will know whether you need a permit for replacing a flat roof or not. 

Therefore, hiring a professional roofing company is always a better option and you can reach out to use it for a free quote. But it’s better to double-check any permits with your local authorities. 

Labour

Hiring professional roofers is always a better option for replacing a flat roof, and it will cost around £2 to £6 per square metre based on the overall complexity of the flat roof job. 

Flat Roof Extension or Removal

Flat roof removal or extension will cost somewhere between £2 to £5 per metre square. So you can either set it aside in your budget or do it yourself. 

Pros & Cons of Flat Roofing

a picture of flat roofing

A flat roof has many advantages as well as some drawbacks. Before you initiate your flat roof replacement projects, consider the pros and cons of these roofs. 

Pros

  • Flat roofs tend to provide extra space for outdoor living, HVAC systems, and rooftop gardens. 
  • A flat roof is a suitable choice for solar panel installation. 
  • These roofs are more affordable as compared to other roof types. 
  • A flat roof is easier to install, maintain, and access. 
  • The flat roof repair cost can be on the lower side.

Cons

  • These roofs are not the best option for areas that see plenty of snowfall and rainfall.
  • Flat roofs have a shorter lifespan as compared to other roof types. 
  • A flat roof is more prone to water damage issues, such as sagging roof, etc. 
  • A felt roof to make your flat roof waterproof can further add costs. 

Doing Flat Roofing Yourself vs Hiring a Pro

It’s better not to go for your flat roof replacements yourself, until or unless you have some serious roofing experience. You need to be a flat roof specialist and have knowledge and expertise for such a project.

If you don’t install your roofs with care and accuracy, it might lead to dangerous and expensive issues for your home. It’s also a matter of safety for you and your family. 

Therefore, it is better to save yourself from any stress and hire a qualified roofer to construct flat roofs. You can get in touch with us for a free quote today. 

Even if you’re looking for flat roof repair, hiring professional roofing companies rather than doing it yourself will yield better outcomes, even if it seems to add to your additional costs upfront. 

Final Thoughts – Why Choose Us for Flat Roofing? 

Flat roof replacement costs can massively vary based on various factors. Whether you’re going for a new roof or opting for another roof type, you still have to tear the old roof off. 

You can reduce your flat roofing costs by handling the project on your own. But we highly recommend you hire a professional roofing company for this purpose. 

Flat roof costs can also vary based on the material and size of the roof. You can hire a quality roofing contractor like us for top-notch services. 

Bristol Roofers has been around for many years, and we have a team of certified and experienced professionals who understand the nitty-gritty of roof installation, removal, and maintenance. 

We can also assist you if you need any permits to meet building regulations. We never compromise on quality and strive to deliver 100% satisfaction. 

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