How Much Does it Cost to Repair a Flat Roof?

Updated Repair Prices For 2021

Repair Instead of Replace

Get a Custom Quote

Welcome to Quotation Check

A Look at Professional Repair Prices and DIY Options

Is your flat roof leaking and in need of repair or replacement?

The good news is that most flat roof coverings that aren’t too old can be repaired, either by a professional or by a competent DIYer.

Below you’ll find the following:

  • Guides to professional flat roof repair prices for bitumen, rubber, mastic asphalt and fibreglass coverings.
  • DIY products that can be used by competent DIYers.
  • An example of when a flat roof repair isn’t viable.
  • Where you can get a custom price online.

1) Bitumen Flat Roof Repair

Bitumen is one of the most popular roof covering products and can be seen on millions of roofs in the UK.

With a life expectancy of between 15 and 25 years, these roofs will need a new covering at some point but you can usually extend the life of the roof if:

  • The roof is leaking in one single location.
  • There’s damage from a one-off incident, such as a falling tile, tree branch etc.

In most cases, a repair won’t be viable if:

  • The roof is sagging between the roof joists – a common sign that the decking underneath needs to be replaced.
  • The surface is showing significant signs of ageing such as; flaking, peeling, bubbling or disintegration in multiple areas.

Professional Flat Roof Repair Cost

Most minor leaks on bitumen roofs can be fixed by the roofer bonding an extra layer of felt over the damaged area.

The image below shows how this is done:

Torch on felt

We expect a minor flat roof repair to cost in the region of £175 – £300 excluding the cost of access equipment if needed.

DIY Options

DIYers should avoid using torch-on products because of the fire-risk and the specialist equipment needed.

They can, however, use a repair sealant, provided it isn’t too runny.

Thin, paint-like sealants rarely work while reinforced products work much better.

Try this repair paste and also use this scrim tape.

Here’s a video from Fix My Roof showing how the two products are used:

2) Rubber EPDM

Rubber EPDM roof coverings are very flexible and usually hold up well to movement and rarely crack or split.

With a life expectancy of between 25 and 50 years, rubber is chosen for its longevity and ease of installation.

The good news is that rubber can usually be repaired if:

  • The roof is leaking in one single location.
  • There’s damage from a one-off incident, such as a falling tile, tree branch etc.
  • Two layers have pulled apart and are no longer bonded together.
  • You can sometimes repair rubber coverings even if the roof is sagging as the rubber is very flexible.

Repairs can be very difficult if the leak is on a joint with another type of roof covering, perhaps a shared roof with a neighbour that has fibreglass or bitumen etc.

Damaged rubber roof

Splits and evidence of previous failed patch repairs suggest this roof covering should be replaced rather than repaired.

Professional Rubber Flat Roof Repair Cost

Most minor leaks on rubber roofs can be fixed by the roofer bonding a repair patch over the rubber.

The image below shows a typical torn rubber roof, this is easily repaired:

Rubber roof repair

We expect a minor rubber flat roof repair to cost roughly the same as a repair to a bitumen roof. A price of £150 – £300 is reasonable. Again, this excludes the cost of access equipment if needed.

DIY Options

If the roof can be accessed safely, there’s no reason why a tear or minor hole cannot be repaired using readily available rubber repair kits.

Repair kits are similar to those used on bike tyre inner-tubes, pond liners, inflatable rubber pools and hot tubs etc.

3) Fibreglass Flat Roof Repairs

Fibreglass is a popular flat roof material, fully waterproof and as hard as nails, it normally lasts for decades.

Unfortunately, fibreglass is so rigid that it’s prone to cracking. Small splits sometimes appear, often the result of the movement of the timber decking underneath.

If your roof has only a few splits here and there, it can likely be repaired.

However, if the fibreglass has delaminated, i.e. entire layers of the materials are lifting off the roof, or the entire surface has bubbled, it may need to be replaced.

Fibreglass Flat Roof Repair Cost

While fibreglass and the bonding resin is fairly cheap, expect minor repairs to cost somewhere between £150 – £300 which covers the time to complete the project.

DIY Options

Fibreglass repair kits cost around £25 for 1 square metre patch and they’re incredibly easy to use.

Try this kit from Amazon:

Fibreglass roof repair

This video shows how easy it is to repair a fibreglass surface:

4) Asphalt Repairs

Asphalt is a heavy material, often found on paths and roads but also on flat roofs.

A good quality asphalt roof will last for decades but the weight of the product and thermal expansion/contraction can result in cracks.

DIY repairs tend to be short-lived as the crack can transfer through any surface repair or overlay. For a quick, albeit short-lived repair, try this compound, it’s very messy but should waterproof the roof until a longer-term solution can be attempted.

A permanent solution can be completed by a mastic asphalt specialist who will reinforce the surface to prevent the crack from spreading. The gap is then filled with hot poured mastic asphalt.

Once repaired, a reflective coating should be applied to the roof to keep it cool so thermal expansion and contraction is kept to a minimum.

It’s difficult to offer a price for asphalt patch repairs as this work needs to completed by a specialist but expect upwards of £250 for a simple straight-forward repair with more complicated repairs running into the many hundreds or thousands.

Asphalt roofs are generally very strong and if they leak, they can be overlaid with a new covering of rubber, bitumen felts or even liquid coatings as seen in the video by London Flat Roofing:

5) When a Repair Isn’t Viable

Repairs aren’t always viable and as stated at the start of this guide, one should consider a completely new flat roof if:

  • The roof is sagging between the joists as this is a sign of the timbers underneath failing, most likely due to water damage.
  • There are large bubbles or blisters under the roof covering, this is usually due to water ingress that can’t escape.
  • Layers are peeling off and/or delaminating.

The video below, again by London Flat Roofing, shows some examples of when flat roofs can’t be overlaid with a new covering, it’s unlikely a patch repair would work on these roofs either:

6) Diagnosing a Damaged Flat Roof

Damaged flat roofs generally fall into one of three categories:

Patch Repairs – These are usually achievable on roofs that aren’t too old, haven’t failed in no more than a few places and on roofs where the decking and timbers underneath are sound.

Covering/Coatings – For roofs suffering from more extensive wear and tear, ageing etc, a new covering or coating can be applied to the entire surface provided the decking and timber underneath is sound.

Complete Replacement – For roofs where the decking and/or timbers have failed and there are obvious signs of buckling, sagging or if large sections are bubbling up, flaking or delaminating, a complete replacement should be considered.

Of course, there will always be overlaps between the categories. For example, a roof may have suffered damage to the decking and timbers to just one area where a localised repair can be attempted.

Find a Flat Roof Specialist

We hope you found our flat roof repair cost guide insightful.

While most patch repairs can be completed for a few hundred pounds at most, overlays and replacement roofs cost much more.

To get a custom price for your flat roof:

  • Get a custom flat roof repair or replacement price.
  • Check vetted reviews and ratings.
  • Compare prices from local tradespeople and specialist firms.

Flat Roof Repair

Get a Custom Price

Discover More Price Guides:

By Quotation Check

Bitumen Flat Roofs

See how much it costs to replace a flat roof with long-lasting and time-tested bitumen felt systems. These layers of felt are bonded to the roof with a gas torch, creating a strong and durable finish.

Rubber Roofs

Rubber EPDM is a popular and modern product that will hold up well in all conditions. Perhaps one of the easiest products to install, rubber can also be patch repaired too.

Fibreglass Flat Roofs

From ship hulls and kayaks to pond liners and car parts, fibreglass can be found on thousands of waterproofed products. Once set, the material is extremely rigid so for the product to last, the roof shouldn’t have too much flex in it. 

Their prices for roofline installations were correct; we were given quotes from several firms, all were similar to [Quotaton Check’s]

Quotation Check’s guides to flat roof prices are very accurate, they include all the extras many other price guides conveniently exclude.

Why only rely on three or four quotes for comparison? This website called Quotation Check gathered prices from hundreds of firms for various home improvement tasks and published their findings online.

Roofing firms often charge more than they should because they think consumers have no idea about how much the parts and labour should cost. Quotation Check’s guides are easy to read and they explain in detail about the materials needed and how long the work will take.

Go see the prices on the Quotation Checker website; they’re suggesting a price for a new roof that’s much lower than that.