Flat roof replacement cost

The cost of a new flat roof is generally in the region of £1,000 – 4,000 in the UK depending on the scale and complexity of the flat roof.

There are several factors to consider when working out a flat roof replacement cost, including the type of material you’re going to use, the drainage system, the size of the roof and ease of access.

GRP roofing costs the most generally at £90 per square metre (m²), although other materials can be more cost-effective. However, it also has the most benefits and lasts the longest. This is a major consideration when working out the cost of a new flat roof.

Other materials such as EPDM rubber and roofing felt are more affordable but come with an array of pros and cons, all of which have an impact on your flat roof cost.

How much does it cost to replace a flat roof?

Most flat roof replacement costs will total in the region of £1,000 – 4,000, depending on the size of your roof. The main three factors a roofer will use to work out your flat roof cost are; the type of the material, the amount of material and the labour involved.

Flat roofs are normally more affordable than pitched roofs to replace. This is because a flat roof requires less material and labour to complete. They also tend to be cheaper overall because homeowners typically use flat roofs for comparatively small surface areas such as garages, extensions, and outhouses.

Below is a table of the most popular flat roof materials and their cost. You can use this to work out the approximate cost of a new flat roof.

Cost of flat roof materials per m²

Type of roofing Cost per m² Cost per 20m²
Felt £40 £800
EPDM rubber £45 £900
Tiles £50 £1000
Slate £60 £1,200
Lead £80 £1,600
GRP fibreglass £90 £1,800

Typically, a roofer will charge around £200 per day with the average roof installation taking three days. This will be added to the cost of the materials in your final flat roof replacement cost. If you shop around, you may be able to get a better deal.

Also, there are some other considerations to take into account when researching the cost of a new flat roof, such as:

  • Any repairs to the pre-existing structure
  • Waste removal of the old roofing materials
  • The location of your home
  • The state of the drainage system
  • How easy your roof is to access

All the factors above will ultimately determine your flat roof cost.

How much does a fibreglass roof cost?

The cost of a fibreglass roof is around £90m², or around £6,750 for a complete roof replacement.

Although the GRP roofing cost is one of the most expensive of all roofing materials, there are several benefits that it brings to the table.

My Local Toolbox recommends asking a local professional roofer to give you an estimate for the cost of a fibreglass roof. It’s not recommended that you attempt to take on the project yourself.

How long does a fibreglass roof last?

The cost of a fibreglass roof can be counterbalanced by the fact that it normally lasts over 25 years without needing to be replaced. This is because GRP fibreglass greatly reduces the pressure points of the roof’s surface where issues can arise.

For example, with other materials such as felt, water ingress can occur where two different parts of the material meet.

With fibreglass, there are no seams, meaning that water finds it extremely difficult to penetrate and cause a leak. This is an extremely important factor, so consider the pros and cons that contribute to a flat roof replacement cost.

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What is the cost of rubber roofing?

The cost of EPDM rubber roofing is around £45m². This means on the average roof; the final rubber roofing cost will be around £3,375.

However, the price can vary depending on which professional roofing contractor you use, so it’s always best to shop around.

One of the most popular types of EPDM rubber roofing is Firestone. This is because of the material’s impressive durability, ease of use and the fact that it needs minimal maintenance.

Firestone rubber roofing costs are extremely competitive and membranes are available in an array of different sizes.

Rubber flat roof cost

How long do rubber roofs last?

In general, EPDM rubber roofs last around 50 years depending on several factors. EPDM rubber roofs are one of the longest-lasting types of roofing material.

It can withstand extremely inhospitable weather conditions such as rain, snow, and sleet over long periods of time. This durability offsets the EPDM rubber roofing cost, as over 50 years the investment is minimal.

To maximise the lifespan of an EPDM rubber roof, it’s vital that you carry out regular maintenance to prevent potentially damaging issues from arising, such as poor drainage and excessive standing water.

Keep these points in mind when calculating a flat roof replacement cost.

What does a felt flat roof cost to replace?

The cost of refelting a flat roof varies depending on its size. Roofing felt costs around £40m² to install. For the likes of a garage, the total project would cost in the region of £800.

There may be additional costs to factor into your calculations when working out the cost of refelting a felt roof.

Firstly, you may have to pay for scaffolding depending on how large your house is. This is so the roofers can work at height safely.

Scaffolding can cost anywhere between £600 – 1,000 depending on the size of the project.

Also, you’ll have to think about removing the damaged roofing felt and disposing of it. A 6-yard skip will cost around £250 to hire.

Flat roof replacement cost FAQ

Is there ever a time where repairing the roof is better than replacing it?

It can be extremely beneficial to repair your roof rather than replace it, with the biggest benefit being that you would avoid the cost of a new flat roof which can be expensive.

If your roof is less than 15 to 20 years old and the damage isn’t substantial, it’s unlikely it’ll need to be replaced due to it not being at the end of its lifespan.

In this case, repairing it would be the preferred option. Also, consider if you’re likely to move home soon and compare the costs involved.

What is the best material for a flat roof?

Although there’s no definitive material that’s the best to use for a flat roof, it’s generally considered that EPDM membranes are the best solution.

The material is made from durable and water-repellent rubber that protects the roof from the elements.

Some of the benefits of EPDM membranes include the comparably low cost versus other materials, its fire-resistant qualities and long life expectancy. Your EPDM rubber roofing cost would depend on the size of your roof.

Can a fibreglass roof leak?

Yes, fibreglass roofs can leak due to several reasons.

Loose or faulty flashings can lead to water ingress.

Also, pinhole-like small holes can form on the surface of the fibreglass because of the coating not being the correct thickness.

Other issues that can arise include the fibreglass roof’s lifespan coming to an end and leaking due to general wear and tear or pools of water sitting on the surface causing drainage issues.

Can you recoat a fibreglass roof?

Yes, it’s possible to recoat areas of fibreglass roofing that are causing leakages in several ways. If you’re researching the cost of a new fibreglass roof, it may be worth considering recoating it instead.

Firstly, a professional roofer would fill in any holes or cracks that have appeared on the fibreglass roof using a waterproof sealant.

Once completed, they would recoat the surface of the roof using GRP restoration coating giving it an extra 15-year life expectancy. A local roofer would assess the size of the recoating project to suggest a GRP roofing cost.

Visit our roofing page for more insights on what to consider when replacing or building a new roof.

If you’re undecided whether to opt for a flat or pitched roof, take some time to read our roof repair cost guide. The guide also includes a handy jargon buster to help you understand the technical side of roofing.

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