Cost Of Replacing A Flat Roof: A Guide

Cost of replacing a flat roof
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Facing the prospect of replacing a flat roof can be daunting for homeowners and property owners alike. Both in terms of the potential challenges and the financial investment required. A common question that arises is, ‘What’s the cost of replacing a flat roof?’ 

This guide aims to demystify the complexities surrounding flat roof replacement, offering insights into common issues, influencing factors, and the various types of flat roofs you might be dealing with. 

By the end, we hope you’ll have a thorough understanding to make an informed decision about this oh-so-crucial improvement project.

Why Should I Replace My Flat Roof?

Let’s start with the obvious things first, and that includes why you would even need to replace a flat roof to start with. When you’re considering the cost of replacing a flat roof, it’s important to first understand the decision you’re making. And if you’re replacing a flat roof, it should be for good reason. 

Usually, replacement is needed if there are issues that go beyond simple repairs and fixes. Common problems that lead to flat roof replacement include:

  • Leaks – persistent water leaks that are beyond repair or have already caused further damage.
  • Pools of standing water – inadequate drainage causes water accumulation and pooling.
  • Splits, cracks and tears – seemingly small structural damages can compromise the overall integrity of your roof
  • Aged roofing system – natural wear and tear occurs, but your system may also be out of date (roughly 10 years for a mineral felt covering)
  • Safety concerns – structural issues can make your building risky for its occupants
  • Inadequate insulation – this contributes to energy inefficiency and further complications

It’s vital that, when you evaluate the choice between repair and replacement, you weigh up the big picture. Consider factors like the effectiveness and longevity of repairs versus the potential benefits of a complete replacement.

What Affects The Cost Of Replacing A Flat Roof?

Understanding what influences the cost of replacing a flat roof is half of the hard work. It’s especially important if you want to wrap your head around budgeting for a flat roof replacement. There’s a lot to take into consideration for your overall expense. 

Here’s what you’ll need to take into account:

  • Size of the roof – larger roofs naturally incur higher costs for materials and labour.
  • Access to the roof – the need for scaffolding or specialised equipment can impact your costs.
  • Roof type – different materials and designs come with various price tags, so beware when choosing.
  • Design choices – opting for intricate designs or extra features can really add to your costs.
  • Waste management – disposing of old materials inevitably adds to the overall price, but it’s a necessary factor.
  • Roofing contractor – choosing an experienced professional may mean a higher price, but the quality of work is often worth the investment and peace of mind.


There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man’s lawful prey.

John Ruskin.

The Cost Of Replacing A Flat Roof

If your decision is leaning toward flat roof replacement, breaking down the costs into specific components might give you a clearer picture. Typically, the process involves…

  • Identifying the issues – First, you’ll need a thorough inspection and assessment of the problems you’re dealing with. This is sometimes offered by your professional roofing contractors as an initial assessment, but you may require further investigation.
  • Creating access to the roof – Installation of scaffolding or other necessary equipment can come with a significant price tag. But it is essential, as without roof access, your flat roof cannot be safely replaced.  All work on roofs is highly dangerous even if a job only takes a few minutes. Proper precautions are needed to control the risk. Anyone working on the roof must be trained, competent and instructed in use of the precautions required. A ‘Risk Assessment & Method Statement’ (RAMS) is the common way to help manage work on roofs and communicate the precautions to those involved. It’s not wise to ask your contractor to take shortcuts, particularly in order to save money. If a client exercises any control over the manner in which a contractor is to undertake work they have a duty to take reasonable care to protect the contractor from harm.
  • Removal of your old, damaged roof – There’s the matter of getting rid of your old, damaged roof so that a new one may be built. This means lots of old roofing material and debris need to be handled and disposed of with proper care – and in an environmentally friendly way, too.
  • Installing the new flat roof – This includes the construction and installation of your chosen roof type and the selected materials. This is no small feat, as it requires specialist knowledge, tools and expertise to get right. 

These are all factors that are unavoidable, but will be specific to your needs and your flat roof type, so you can see how much the cost of replacing a flat roof might vary. But if you’d like to get into the numbers, you can get an even better idea of cost.

Getting Into The Numbers

To give yourself a more detailed estimate based on the square meterage of your roof, consider these figures as a general guide…

  • 3m x 5m(15sqm): £4000 to £8000
  • 4m x 8m (32sqm): £8000 to £12000
  • 5m x 12m (60sqm): £15,000 to £20,000

The price will vary depending on the type of flat roofing you choose, the size of your roof and the other factors mentioned above. You can learn more about the cost of a new flat roof in this guide here – or get a online instant estimate for your roof using our pricing calculator.  

But cost isn’t the only factor you need to consider. The longevity of your roof is important too. A flat roof that costs less now, but has a shorter lifespan, will cost you more in the long run. 

How long does a flat roof last? It depends on several factors, but here’s a rough guide on the longevity you can expect from each type of flat roof. 

  • Mineral Felt  – Average lifespan of 1-8 years
  • Fibreglass (GRP glass reinforced plastic) – Average lifespan of 1-15 years
  • EPDM (ethylene propylene diene monomer, synthetic rubber) – Average lifespan of 5-15 years
  • PVC single ply – Average lifespan 20-40 years

When you’re evaluating your costs, it’s crucial to consider the long-term value you’re going to get from your roof. A quick fix won’t seem so quick when you’re replacing your roof again the very next year. A higher initial investment may well translate to better value over time if your chosen roof has a longer lifespan.

The Benefits Vs The Cost Of Replacing Flat Roof

While the cost of replacing a flat roof may seem daunting, it’s essential to consider the benefits that will come with your investment:

Improved energy efficiency – new roofing materials are often better insulators, leading to lower energy costs.

Added home value – a well-maintained and modern roof adds to the overall property value.

Enhanced safety – A structurally sound roof means safe occupants.

Quick installation – modern roofing methods are often faster to install.

Longevity – a new roof provides peace of mind for years to come.

Low maintenance – Newer roofing types often require minimal upkeep, reducing long-term costs, too.

Cost Of Replacing A Flat Roof: A Guide

Making Your Flat Roof Replacement Choice…

The cost of replacing a flat roof is undeniably a significant investment. But with the right information and careful consideration, it can be a wise and cost-effective decision. If you’re thinking about a flat roof replacement, our experienced team is here to help. You can get an instant estimate for replacing your flat roof on our online price generator here. 

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