Common Causes of Roof Leaks

A man checking a roof leak


As the autumn season rolls in, many people are are thinking about how well their roof will survive the winter. Heavy rain and even snow is sure to hit us at some point in the coming months, and that means it is important to know what damage it can cause, and roof leaks are one of the most common issues affecting roofs.

Understanding the common causes of roof leaks can help you prevent them, spot them early and fix them before the damage gets out of hand.

To make sure your roof is functioning properly, here are some of the most common causes of roof leaks.

Clogged Gutters

Guttering is designed to drain water away from your roof. When guttering fails or gets clogged by branches, mud or other debris, rainwater cannot be drained away easily. This causes water pooling against your roof which leads to leaks. Any insufficient drainage on a property can lead to roof leaks, but luckily, the solution to this is simple.

  • How to Spot

Regular inspections of your guttering should help you to spot when your gutter is clogged. Watch out for leaves, branches or large quantities of mud along your guttering and watch for any downpipes that don’t seem to be pouring out water while it’s raining.

  • Solution

Clearing your guttering of any debris will help you prevent roof leaks caused by this problem.

Slipped Tiles/Slates

Bad weather can sometimes cause tiles or slates to slip off, leaving roof underlay exposed. Large quantities of rainwater can then pool in that area, making a leak increasingly likely to occur. The same thing can happen when slates/tiles crack or chip.

  • How to Spot

This is one of the easiest things to spot because it is usually visible from the ground. If you suspect any small cracks or chips in your roof tiles, you may have to get a closer look. But remember, don’t do anything that you are incapable of and call a professional if you are unsure.

  • Solution

Usually, the only solution to a slipped roof tile or slate is to get it replaced. Make sure you find an appropriate replacement tile that is the same material and colour to avoid it sticking out or looking odd. Again, if you are unsure, it is always best to get some help.

Underlay Failure

Even though roof tiles and other forms of roofing are designed to keep rainwater out, there is still a chance that extreme weather can cause water to seep through gaps. One of the purposes of underlay is to carry this water away but, overexposure to this can cause the underlay to rot. If this happens, the underlay will not function properly, and roof leaks may occur.

  • How to Spot

Failed underlay can be very difficult to spot before a leak occurs because it resides underneath the roofing. The best thing you can do is carry out regular inspections of your roof from inside and outside the property. This will alert you to any problems that can lead to rotting underlay or have been caused by rotting underlay.

  • Solution

If you catch it early and the damaged area is small, you can patch it up. But first, you will need to remove the roof that is covering it and replace that afterwards. However, larger areas of underlay damage may require completely new underlay. It is impossible to replace only the underlay, so you will also need an entirely new roof. This makes regular inspections of your roof vital, particularly before and after bad weather periods.


Condensation is not a direct cause of a roof leak. But, if your roof is poorly ventilated, then condensation can form on the underside of the underlay or tiles. This leads to small water droplets dripping down, which is often mistaken for a roof leak.

  • How to Spot

Keep an eye out for any slow dripping water in your loft or attic and don’t always assume it is caused by a roof leak. You might also spot an issue if you hear cracking noises against the roof. Cracking occurs when a layer of condensation freezes in very cold temperatures.

  • Solution

To prevent this problem, consider how to reduce moisture in the property and whether you need to add ventilation measures to your roof. Check that any insulation hasn’t covered ventilation holes. If you are unsure, call a professional who will be able to advise.

Built-Up Debris

Built-up debris doesn’t only block guttering, it can also cause roof leaks if it is left lingering on your roof. Whether it’s branches, leaves or other debris, it traps water against the roof which makes it more likely to cause roof leaks. It can also prevent rainwater from running into the gutter, causing insufficient drainage.

  • How to Spot

You can usually see when there is any debris on the top of your roof if it is sloped, but on a flat roof, you may need to get up a ladder to have a look.

  • Solution

Removing any debris as quickly as possible will help you to prevent this leak-causing problem. It is also useful to trim back any overhanging trees which may cause regular debris falling on your roof.

man removing roof debris

Damaged Roof Junctions

Roof Junctions, corners and flashings are some of the most likely places for a roof leak to occur. It can happen when it hasn’t been correctly installed or when there is a little damage. The smallest gap in roof flashing or junctions can lead to massive issues.

  • How to Spot

You may need to get close to your roofs detailing to spot any small gaps. Some you can see from the ground, but if you’re uncomfortable working at a height, you may need to get some help to spot this issue before you get a large leak.

  • Solution

Very small gaps in roof flashing, junctions or details can sometimes be fixed using a strong sealant or filler. Mostly, this is best used only as a short-term solution. In many cases, the flashing or junction will need replacing and installing to a higher standard.

Roof Valleys Unsealed

If you have valleys on your roof (where two sloping planes meet), then a common cause of roof leakage is valleys that aren’t sealed together sufficiently. If the seal is weak, water will seep through and will cause roof leakage or other damage.

  • How to Spot

This is often difficult to spot because it can occur in many different places along the seal and it is hard to know where exactly the problem is. Because of this, the best thing to do is contact a professional if you suspect a problem and get them to give your roof valleys an inspection.

  • Solution

The good news is that this can be easily corrected, but it will have to be carried out by a professional under most circumstances.

Rubber Tears

If you have a flat rubber roof such as EPDM membrane, tears or other damage can sometimes cause roof leaks. Despite the fact that EPDM has a reputation for being very strong and resistant, extremely worn EPDM can sometimes get tears or splits which can cause water to seep through, creating a leak.

  • How to Spot

A small inspection of your flat roof will normally alert you to any tears and splits because they are in plain sight. Taking notice of these things and acting quickly is the key.

  • Solution

The great thing about EPDM rubber roofs is that they can be repaired very easily. You can buy simple repair and patchwork kits that will help you to repair your roof until it is as good as new.

So there you have it. Identifying common causes of roof leaks can help you to prevent them. To find out more about how to prepare your roof for winter and the bad weather, read this blog post. For more information about EPDM rubber roofs, visit the rest of the Avenir Roofing website.

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