It costs about £1,000 to £6,000 to replace a flat roof. However, this depends on the size, type, location and accessibility of the roof. So, the answer to this question is a little complicated.

Still, I will share some estimates with you. I will also discuss everything we usually tell clients who hire Fixmyroof for flat roof replacement. I will tell you:

• Flat roof replacement costs per square metre
• The types of flat roofs and their costs
• Additional costs of replacing a flat roof
• When to replace a flat roof
• When to repair a flat roof instead of replacing it

Roof replacements are normal. Even gable and hip roofs need to be replaced at some point. So, this topic doesn’t make flat roofs less cost-effective and ideal for your home or office. 

Anyways, let’s talk about flat roof replacement costs. Let’s discuss everything you need to know about the process.

How Much Does a Flat Roof Replacement Cost?

On average, a replacement flat roof costs £1,400 to £6,000. This usually adds up to around £45 to £140 per square metre. Again, the amount depends on the type, size, location and accessibility of the flat roof.

The roof type is one of the most important cost factors. Here are some examples.

• Felt flat roofs cost £45 to £70 per square metre
• Single-ply membrane flat roofs cost £70 to £100 per square metre
• Liquid flat roof costs £80 to £140 per square metre 
• Green flat roof costs £60 to £120 per square metre

About 55% to 70% of the money goes to supplies. The rest will cover labour and waste removal. Either way, these estimates should be enough to get you a replacement flat roof from Fixmyroof (us) or any of our competitors.

There will be exceptions. So, contact us or another qualified roofer to know exactly how much it will cost to replace a particular flat roof. To give an accurate quote, the roofer must inspect your roof and know your choice of roofing material.

Ask for a full breakdown. Some roofers don’t include VAT or waste removal costs in their main quote. They may also not include the cost of removing the old roof. So, get a full breakdown of the quote to avoid misunderstandings.

Factors Affecting the Cost of a Flat Roof

Here are the six factors that determine flat roof costs.

Type of flat roof

Earlier, I mentioned four types of flat roofs, namely single-ply membrane, liquid, green and felt. These are just the main types. Both single membrane and liquid roofs can be divided into more types.

However, that’s a conversation for later. So, for now, let’s focus on the main types of flat roofs. Felt flat roofs are the cheapest, while liquid roofs are the most expensive.

Installation mode also matters. A flat roof can be warm or cold. In warm roofs, insulation is installed above the roof. In cold roofs, insulation is installed between the roof’s layers. Warm flat roofs cost more.

Size of the flat roof

Size is another big factor that affects flat roof replacement costs. A bigger roof will cost more. Fortunately, it’s easy to get estimates. Simply multiply the size of your roof (in square metres) by the cost of the type of flat roof you want.

For example, you need £1,350 to £2,100 for a felt flat roof of 30 square metres.

Your Location

It’s mainly about the standard of living in your area. Southern UK and big urban cities have a higher standard of living. Therefore, flat roof replacement costs might be higher. For Northern UK and rural areas, costs will be lower.

Accessibility

Flat roofs are generally accessible and easy to work with. However, there could be issues. For example, the building could be very tall. There might also be a structure or object that can disrupt or delay the project. Any of these could affect flat roof costs.

Let’s use building/roof height as an example. Scaffolding is usually needed to replace a roof. The taller the building is, the taller the scaffolding needed. Scaffolding hire alone can increase flat roof replacement costs by up to £1,500.

Waste removal

We’ve talked about this earlier. Remember that some roofers may not include waste removal costs in their quotes. There is also the cost of disposing of the old roof. So, don’t forget to ask your roofer for a written cost breakdown.

Waste removal alone costs about £100 to £250.

Additional costs

These happen on the average home improvement project. For example, the roof’s frame may need repairs, and the gutters may need cleaning. Either way, it will affect the cost of replacing the flat roof.

Here are three common additional costs of flat roof replacement.

• Flashing repairs: £100 to £500
• Roof timber frame (structure) repair: £200-1,400
• Gutter cleaning or repairs: £100 to £350

Types of Flat Roofs

There are many types of flat roofs. So, I will only tell you about the main four. I will also tell you how much each one costs.

Single-ply membrane flat roof

This type of flat roof is usually made from EPDM (Ethylene Propylene Diene Monomer), TPO (thermoplastic polyolefin) or (PVC) polyvinyl chloride. Essentially, they are synthetic rubber roofs.

Single-ply membrane roofs are durable, water-resistant, heat-resistant, lightweight and eco-friendly. They are also easy to install and suitable for all roofing situations.

There are some weaknesses. Single-ply membrane roofs fade over time and break down under heavy foot traffic and weather. Plus, design choices are limited.

The average single-ply membrane flat roof costs £70 to £100 per square metre.

Felt flat roof replacement cost

This is the most affordable type of flat roof. Felt flat roofs cost £45 to £70 per square metre. Felt is cheap and relatively easy to install and replace. It is also low-maintenance.

There is just the problem of durability. Felt roofs are not as durable as the others. They don’t last as long. They also can’t survive extreme weather conditions. Plus, repairs will make the roof patchy, ruining aesthetics.

Liquid Flat Roof Replacement Cost

Liquid flat roofs are usually acrylic, bitumen or fibreglass. They are durable, lightweight, waterproof and great for surfaces of all shapes and levels of evenness. They are also easy to repair.

On the other hand, professional installation is crucial. A liquid roof is also high-maintenance and prone to slips, punctures and sun damage.

The average liquid flat roof costs £80 to £140 per square metre.

Green flat roofs

A green flat roof is also often called a living roof. To build one, you install a growing medium. Then, plant on it. This encourages vegetation and wildlife, giving your building a unique aesthetic.

A green roof is energy efficient and noise cancelling. However, it is also high maintenance, costly, heavy and prone to leaks. So, it’s crucial to install waterproofing under the growing medium.

The average green flat roof costs £60 to £120 per square metre.

When Should You Replace a Flat Roof?

It costs a decent amount of money to replace a roof. So, people are often tempted to keep repairing and using a bad roof.

This is dangerous. It’s a hazard to everyone and everything under that roof. At the very least, it could damage the roof’s frame. This will further increase the cost of replacing that roof.

Once the signs show up, there is no other solution. You must replace that roof. So, here are the signs that a flat roof needs replacement.

Leaks

Leaks are repairable. Just call an experienced roofer first. Let the professional examine the roof and recommend a solution. If the leaks persist (especially after several repairs), it’s probably time for a new roof.

Water pools

Still, pooling could be a sign that the roof needs to be replaced. If you don’t do something quick, the roof will start leaking. The support frame may also get damaged.

Flat roofs aren’t actually flat. They usually have a slight slope to aid drainage. However, drainage is still one of the biggest weaknesses of flat roofs. So, water pools may happen occasionally, especially after heavy rains.

Moss and mould

Algae, mould and fungus are signs of drainage issues. They grow in water pools and damp cracks. They ruin the aesthetics of the roof. Imagine those unsightly green creatures on your roof deck.

So, don’t allow water to pool on your flat roof. Treat algae, mould and fungi as soon as possible. If the problem persists, replace that roof.

Cracks, punctures and blister

Over time, any structure will have cracks, punctures and blisters. It’s a natural result of wear and tear from daily usage and the weather. It’s also a sign that the structure (in this case, the flat roof) is old and tired. Therefore, it should be replaced.

The problem will only get worse. The cracks and holes could leak. Blistering is the peeling of the outer weather-resistant layer of the roof, thereby exposing the inner layers. This also makes the roof vulnerable to weather damage.

Sags and bleaches

Sagging is usually a result of problems with the roof itself or its timber frames. Bleaching, on the other hand, is caused by old age, the sun and the weather. They both make the roof look horrible. Sagging also encourages flooding.

When a roof is sagging and bleaching, it might be time to replace it.

How Much Does Flat Roof Repair Cost?

Flat roof repairs cost around £150 to £2,000. However, this depends on the type of repair and the scale of the damage. For example, roof frame repairs could cost as much as £2,000. Meanwhile, gutter repairs cost only £170 to £300.

Should You Repair or Replace a Flat Roof?

The signs are the same. So, it’s tricky. Sure, there are times when the decision is easy to make.

For example, when a flat roof is old and dilapidated, you can easily tell that replacement is the only viable solution. Also, when a healthy flat roof has a minor problem, it’s clear that you only need to repair and not replace it.

Then, there are times when the answer isn’t really clear. In those cases, what should you do? Call a professional. It’s that simple.

I recommend calling a professional in any situation. Whether you want to install, repair or replace a flat roof, call a professional. The professional will help you make the right choice.

Let’s assume you hire Fixmyroof to repair or replace your flat roof. Our roofing experts will first inspect every part of the roof. We’ll also examine the timber frame. Only then will we recommend repairing or replacing the roof. 

There is no guesswork. Our decisions are based on expert examination. We can also help you make a lot more informed roofing decisions. Contact us anytime.   

How Much Does It Cost to Remove a Flat Roof?

Flat roof removal costs around £70 to £100 per square. This should cover the labour and supply costs of removing and disposing of a flat roof.

How Much Does It Cost to Install a New Flat Roof?

It costs £500 to £6,000 to install a new flat roof. Here are some examples.

Summary

Flat roof replacement costs £1,400 to £6,000 or £45 to £140 per square metre. Remember that this depends on the type, size, accessibility and location of the flat roof. There could also be additional costs.

Either way, this is a very good investment. Flat roofs are a cost-effective and versatile roofing solution for commercial and residential properties. Plus, you probably won’t need to replace it in the next 10 to 50 years.

When the time does come, it’s crucial to hire a reliable and experienced roofer like Fixmyroof. We offer gable, hip and flat roof installation, repair, and replacement in various parts of the UK. Actually, we do a lot more than that. We are experts in all sorts of roofing solutions.