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Common causes of roof leaks and how to fix them

  • 20, Jun 2021
  • Read time: 12 mins

This guide will help you to understand the common causes of roof leaks and some of the steps that can be taken to fix the problem. If you spot a roof leak, don’t put it off; it’s time to sort the issue immediately.

Roof leaks often go unnoticed for some time. Damp can build up slowly, especially when the cause of the leak is just a small crack or hole. Remember, ‘maintenance and wear and tear’ is not covered on our policies, so if you have a roof leak, you’ll need to fix the issue quickly.

Rainwater leaking from the guttering.

Damp may not always show directly below the root cause, due to the pitch of the roof. Water can find a way in through one point of your roof, and find its way down to a seemingly unrelated part of your house, so careful investigation is always needed.

Some leaks are easier to spot than others, but all may result in costly damage. So, don’t wait too long before acting on any household damp that you notice.

How to find roof leaks

Always check your roof for signs of wear and damage, particularly after a storm. You can do this curb side, establishing whether this is a DIY job, or better left to the professionals. If access is straightforward it may be possible to fix the problem yourself. However, if you’re at all unsure, it’s probably wiser to give an authorised tradesperson a call.

If you are attempting repairs yourself, get the right tools for the job, including ladders or scaffolding for easy access and remember to take your time, picking the right day to begin repairs.

Missing tiles are often visible from outside, but if you can’t see anything obvious, try going up into the loft. Shine a torch onto the inside of the roof on a rainy day, as any water will reflect in the torchlight if it's leaking in.

If dry weather is forecast but you still want to spot leaks, use a garden hose and gently spray the area you believe to contain the leak. Make sure you also have a spotter working on the inside, ensuring they’ve protected the inside of the home for potential water damage.

If you do locate the leak and you’re not sure of how to fix the issue, call in the experts immediately.

How much does a roof repair cost?

A roofer will not charge based on time, but on the complexity of the task.

Even a simple tile replacement task may have added complications, such as the need to erect scaffolding for access where ladders are not safe or sufficient to do the job.

You could be living in a bungalow or a five bedroomed detached home. The height of your property will be an important aspect of any roof repair.

There may be added complexity if the roof has different levels, with tricky access issues including skylights, dormer windows or various chimneys to navigate.

So, when trying to estimate the how much your roof will cost to fix, approach the job from a roofer’s perspective. Don’t always assume it’s a straightforward task.

Common roof leak causes

Here are some of the common causes for your roof to leak. Knowing the signs can help with those spot checks for general roof maintenance before a problem gets more serious.

Missing or cracked tiles or roof slates

Missing tiles or cracked roof slates are easier to spot upon inspection. You can expect to pay around £200 for a relatively simple replacement of several roof tiles

Flat roofs and valleys

Water can pool in low spots on flat roofs or collect in valley gutters if they are not laid to the correct pitch or have become blocked. In this case water will leak into the roof directly below the pool. This can be fixed but you’ll need to call an expert, so try The National Federation of Roofing Contractors Limited (NFRC) to find a local repairer.

Flashings and joints

Flashing around roof joints, skylights and chimney stacks can often be a culprit of damp. Over time the metal and sealant corrodes and needs re-sealing or replacing. Mortar joints in the brickwork of chimney stacks, and the mortar beds of chimney pots can also be damaged by frost.

Ensure any obvious gaps are sealed and old flashing replaced at the first sign of a leak. If you’re in an older property, consider asking a local contractor to carry out a roof inspection every few years. Prevention is half the cure. The cost of repairing flashing can be between £100 and £250 per metre. 

Failure of underlay

Holes in felt underlay can help contribute to a loss of tiles or slates in adverse weather, as well as being a source of a leak itself.

If you have access to your loft you’ll be able to see the underlay.

Tears can be repaired quite easily, but if it’s rotting that’s causing the damage, the underlay will probably need replacing.

The cost of replacing underlay will be factored into the overall price of repairing the damaged area as it is a job that will include removal of tiles and other tasks.

Blocked guttering

You can usually spot a blocked guttering problem by water gushing down from the area of the blockage when it rains. Ensure you clean out your gutters regularly, particularly during winter when leaves and moss can accumulate. If you’re not comfortable attempting this, then a reasonable price for this type of work would be in the region of £4 per metering of guttering

Soffit and fascia damage

Soffit and fascia not only keep your guttering in place, underpinning and encasing the area under roof beams, but also help to keep water away from the wooden framework under the roof.

As well as keeping your gutters clear, you should ensure that soffits and fascia’s are regularly repainted to protect against rot. Alternatively, you could consider replacing timber with lower maintenance PVC boards.

Brick chimneys

Repairing brick chimneys is never an easy proposition. Not only are they difficult to get to, but they take a battering from the elements. What appears to be a simple fix, can sometimes turn out to be quite an extensive task. Mortar joints in the brickwork of chimney stacks, and the mortar beds of chimney pots can also be damaged by frost. Plus, chimneys come in various shapes and sizes and the complexity of the task will involve navigating around these carefully.


Skylights are a popular and cost-saving addition to any home, flooding attic spaces with welcome sunlight. Made of acrylic or polycarbonate, on the rare occasion they do go wrong it’s important to know what your options are. Here are some common issues that skylights suffer from:

  • Daylight glare and UV damage – this is caused because the skylight is usually always in direct contact to the sun’s rays
  • Rainwater and snow contact will cause damage over a number of years
  • Heat can escape through a window just as easily heat can also be transmitted through it. Pay attention to the skylights placement when installing.
  • Ice dams can form during colder months allowing water to pool and seep into the house through seals and flashings
  • Bathrooms are not ideal places to have skylights due the constant levels of warm moisture present. Use ventilation fans to extract the air outside

Your residential skylight will usually sit on a raised curb surrounded by tiles while metal flashing will keep it watertight. Replacing a small Velux skylight may cost between £500-£800.

How to prevent leaks in the roof

If you want to keep a roof over your head, get to know your roof and its various strengths and weaknesses so that you can spot issues before they become serious.

  • Regularly inspect your roof and particularly after bad weather
  • Be diligent about clearing debris from gutters as this can quickly lead to more serious problems if left for a long period of time
  • Where possible, cut back trees from getting too close to your property. As flying or falling debris, such as leaves and algae, will always find a place on your roof, slowly causing decay that can result in leaks
  • Check chimneys and ventilation ducts are well maintained. A roof that is poorly ventilated may suffer slowly from rotting wooden structures that are initially difficult to spot from the outside.

Does home insurance cover roof leaks?

Make sure you understand exactly what your buildings and contents insurance covers you for in the event of damage to your roof. 

MORE THAN, like most insurers, won’t cover general wear and tear. However, if your roof is damaged during a storm it will be covered. 

Your insurance may have emergency assistance that provides cover for, among other things, an emergency repair to your roof. We offer up to £200 home emergency assistance to secure or make your home safe with the option to upgrade your home emergency cover. Upgrading gives you up to £1,000 to fix, among other things, roof damage that threatens further damage to your home.

    Learn more about our home insurance cover

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