Flat roofs are becoming more popular in the UK – not just for buildings like sheds and garages, but for homes and commercial premises, too. In this article, we’ll look at when and how to replace a flat roof, the signs to look out for and the likely cost of replacing a flat roof.
How long does a flat roof last?
The main factors affecting the lifespan of a flat roof is the material it’s made from.
Many flat roofs are made from a mineral felt or asphalt base with a rubber coating. This traditional roofing felt is cheap and easy to fit, but usually only lasts around 10-15 years before it needs replacing. Similarly, a built-up roof, made up of layers of waterproof material, hot tar and gravel, can last for 15 to 20 years.
Newer materials are generally more durable and will last a lot longer. For example, an EPDM (ethylene propylene diene monomer) roof made with a flexible rubber membrane can last around up to 50 years with very little maintenance.
Other factors affecting the lifespan of a flat roof include location, weather conditions, ventilation and maintenance.
Is it better to repair or replace a flat roof?
Whether it’s better to replace or repair your flat roof depends on the extent of the damage, plus the age of your roof. If it’s seen better days, you might be tempted to upgrade it for newer materials and avoid making a series of repairs in the near future.
However, it’s a mistake to automatically assume your roof needs replacing. Eurocell stocks a range of industry-leading products for flat-roof maintenance and repairs, which can extend the life of your flat roof by many years.
Can I repair my own flat roof?
Small cracks or blisters are relatively easy to fix yourself. For a felt roof, smaller leaks or splits can be fixed with flat roof sealant, while bigger areas can be patched with a new layer of adhesive or torch-on roofing felt or a range of Liquid roofing products. Repair kits are also available for Hybrid Polymer, fibreglass and EPDM roofs.
If damage is more extensive, with several areas of the roof needing attention, ask a roofing professional to advise you on whether to replace the whole roof.
Signs you need to replace your flat roof
There are several signs a flat roof may need replacing.
Leaks
Holes, tears or obvious damage to the roofing membrane can be caused by external factors such as falling branches and vegetation growth. But leaks can also be caused by incorrect installation or poor-quality materials, which creates a bigger job.
Rotting
If water is pooling on the top of a flat roof rather than draining away, it can cause issues such as water damage, rotting ceiling boards or a buckling roof. If this is the case for you, we recommend seeking advice from a professional roofer.
Weather damage
Years of exposure to harsh weather conditions and UV rays can cause flat roofs to split, crack, blister or stretch. It’s a common issue when certain materials, such as EPDM, become older and more brittle.
Age
No flat roof will last forever, so if yours is starting to look a bit scruffy you might want to think about upgrading before you find yourself making emergency repairs. A newer, better-performing roof will also provide increased protection, improved insulation and a smarter appearance.
Cost of replacing a flat roof
Checkatrade estimates that, depending on what needs fixing, a flat roof replacement will cost between £1,440 and £3,400 (according to figures in 2024), or £45 to £100 per m². That includes labour as well as materials, so completing some (or all) of the work yourself will bring the totals down. If you’re gathering quotes, a good tip is to ask for an estimate without labour costs for a better comparison.
Another guide, from priceyourjob.co.uk, breaks average costs down by roofing material:
| Flat roof replacement material | Average cost per m2 |
| Roofing felt | £40 - £60 |
| Liquid Roofing | £30 - £80 |
| Fibreglass | £70 - £100 |
| EPDM | £80 - £90 |
How long does it take to replace a flat roof?
The amount of time the work will take depends on the size and complexity of the roof, as well as the materials used. Assuming you’re working with professional roofers, you can expect a garage or porch flat roof to take two to three days, an extension to take up to four and a whole house up to five days.
How to replace a flat roof
The method for replacing a flat roof varies depending on the material you’re using. For an EPDM roof the process briefly involves:
- Cutting up the old membrane and pulling it up in sections
- Cleaning and preparing the roof’s surface (usually timber decking)
- Rolling out the rubber roofing material and laying into position across the full roof
- Smoothing it out to make it completely flat, then trimming excess pieces
- Pulling the roofing material back and applying a water-based adhesive to the decking
- Securing edges, corners and details with a stronger adhesive
While a simple repair is easy enough to do yourself, a whole flat roof replacement is probably best left to professionals, especially if you’re using a material you’re less familiar with. Not only is it important that the roofing material is fitted perfectly, there’s also the safety consideration of working at height.
Best materials for a flat roof replacement
So, what’s the best flat roof replacement material? It depends on your priorities, budget, building type and roof size. For a fast, cost-effective repair or replacement, traditional roofing felt or a choice of Liquid Roofing is still a great option. For something longer lasting, EPDM offers value for money, high performance and durability.
There’s a more detailed explanation of different flat roof types, including built-up roofs, roofing felt, fibreglass, EPDM and green roofs, in our buyer’s guide.
Are flat roofs worth it?
Whether you’re replacing an existing roof or considering a flat roof for your extension, the options have never been better. New materials provide decades of reliable performance for less than the cost of a pitched roof, with easier maintenance. Flat roofs can make a striking visual feature too, giving homes a clean, modern look that can be enhanced with a skylight or roof lantern.
Just as flat roofing materials have become more advanced, so have repair products. Take a look at our industry-leading flat roof repair products and to get in touch if you’d like any help or advice.