Why Is My Roof Leaking?


April showers are a real thing! Whilst showers may ‘bring May flowers’, these small, frequent amounts of rainfall can cause problems for houses and rooves. You may notice your roof leaking more in these wetter spring months than in the dry, cold spells of winter, or in the heat of the summer. Some areas in Cornwall- particularly Bodmin Moor- can get especially high rainfall during early spring, as well as being exposed to strong wind. Roof leaks and repair work is common during this time of year! If you have noticed water coming into your house, or damp patches caused by your roof leaking, you will need to get it repaired as soon as possible, and should call experienced roofers. The longer you leave it, the worse the problem will get. But what are the most common causes of a leaky roof? What is likely to be going wrong? And what can be done to fix it? This article will explain the likely causes of a leaking roof…

Why is my roof leaking?

One of the most common causes of a leaking roof is damage or poor installation of lead flashing. Lead flashing is an important part of a well-protected roof.

Lead flashing

Flashing is installed at the joints of your roof to seal and protect these vulnerable areas from water infiltration and pest infestation. If your flashing becomes cracked or broken, it might soon become the ideal location for a roof leak to begin and cause major problems. Age-related wear and tear, exposure to varying temperatures, physical impacts, or even loose fixings or caulk can all cause flashing to fail. Any cracks or other damage to your flashing should be visible if you examine it closely.

It is vital to fix your lead flashing as quickly as possible due to the critical location of flashing around areas such as skylights, chimneys, or simply where two sections of roof meet. To replace broken lead flashing, first, pry out any fasteners and replace them with a new line of flashing. This should then be secured using roofing nails, which can be further protected by coating the nail heads with roofing sealant. Even if you don’t suspect a problem, we recommend inspecting your roof’s flashings a few times a year. You can read more about what lead flashing is in this article. To understand more about how we make sure that lead is safe, read this blog post. And to see some examples of our previous lead work, you can visit this link.

Age-damaged rooves

The most common reason for a leaky roof is that the roofing components have reached the end of their useful life. While most roof tiles are built to survive for decades, their level of protection will ultimately deteriorate, making them more vulnerable to water infiltration. You may reduce the danger of this happening by performing routine maintenance, such as cleaning moss from your roof tiles, but nothing lasts forever. Extreme temperatures, poor weather, collisions, and debris all wear down your roof over time, making the tiles more brittle and leading to cracks down the road.

Flat-roof leaks

Acute damage, such as tears or punctures produced by collisions, or pooling water owing to faulty installation, is often the reason for flat roof leaks. Both of these can quickly result in roof leaks, as breaches in the roofing membrane or felt allow water to enter easily, and pooling water puts additional strain on the material and structure underneath.

You can see some examples of our flat-roof work by clicking here.

A leaking lean-to

It’s critical to evaluate your garage or extension with a lean-to roof on a frequent basis if it has one. This is especially critical if the lean-to is located beneath your main roof, where rainwater is frequently lost. The repetitive impact of this water, combined with rising moisture levels, will eventually weaken this roof, resulting in a leak through the roofing membrane or its underlay.

Roof tiles that need repairing

Roof leaks are frequently caused by broken or loose roof tiles. Any sources of damage, such as falling debris, will almost certainly influence your roof tiles, which serve as the principal means of protection throughout the majority of your roof’s surface. While many roofing materials are engineered to withstand a lot of abuse, they can only withstand so much before giving way. It’s easy to spot broken or missing tiles on your roof, and heavy winds may leave chips or full tiles strewn around your back garden.


Trees are beautiful and important for our environment. However, an overhanging tree can risk damage to your roof tiles due to fallen limbs, trash, bird poo, and other factors, all of which can lead to roof leaks. If branches and leaves have fallen onto your roof, especially in the autumn and winter, they may be cracking or chipping away at your roof tiles. If the leaves find their way into your gutters, you’ll soon be dealing with a clog. Pruning back overhanging tree branches or even removing the tree altogether is the best approach to prevent roof leaks.

Roof membrane

While roof tiles or slates serve as the first line of defence, there is always the risk that they will be destroyed, exposing the membranes beneath. While roofing underlays like breather membranes are designed to handle modest amounts of moisture and transport it to your gutters, if they are pushed to bear too much water, they can rot away or rip, producing a continuous leak every time it rains.


When uninvited guests such as rodents or birds create a home on your roof, one of the most prevalent causes of roof leaks is. Mice and rats looking for a place to live can often carve out a den in your roof space, making any existing holes much larger and more problematic than they should be! The best approach to deter wildlife from making your roof their home is to keep it clean and free of debris, as these pests are often drawn to falling branches and leaves. For additional information, see our guide to preventing birds from building nests under roof tiles.

Roof pitch and roofing materials

Roofing materials such as tiles, slates, and sheets are only intended for use on roofs with a specific pitch range. Furthermore, depending on the pitch of your roof, the way you install your roofing varies. Roofs with a shallow pitch, for example, may require a double-layer of underlay to give the same waterproof protection as roofs with a higher pitch. However, if your roofer gets this incorrect, it can quickly lead to costly problems like a leaking roof.

A tiled roof with a low pitch is more exposed to the elements, particularly heavy winds and rain. This is why many manufacturers recommend that you leave less of a gap between each tile and use extra fixings for added security. Roof leaks caused by incorrect materials or installation can be prevented by consulting the manufacturer’s guidelines, and ensuring that the roofing materials you choose are appropriate for your roof’s pitch and that they are installed correctly. An experienced roofer will ensure that all materials are appropriate for your pitch of the roof.

Rooves are not designed to bear the weight of humans!

Many roofing materials are designed to withstand the harshest weather conditions. They are not, however, meant to support the weight of a human being. If you’ve been working on your roof, take care to only step on the pinnacle of tiles and use boards to guide you. This is because walking on your roof can easily cause roof tile cracks, which can lead to a leak in the future.

‘Un-fixed’ fixings

When fixings are not secured into the rafters or nails are protruding into your roof space, this offers a direct route for water ingress and leaks. These are particularly troublesome just after a cold snap, as the nail may frost over during cold weather, but as it warms this ice will turn to water and begin dripping down. This issue can be made worse by poorly ventilated or insulated loft spaces, which are a breeding ground for excess moisture, which will only exacerbate the issue. To remedy poorly placed fixings, you’ll simply need to pry the fixing up and seal the hole left behind.

Leaking roof valleys

Valleys are a frequent weak area where two sections of roof meet, making them more prone to roof leaks. It’s only a matter of time until water finds its way in and causes a leak if the flashing installed along your roof valley has become damaged or wasn’t done correctly. Search for wet patches along the seams of your roof to see if your roof valley is leaking, or alternatively, verify that the flashing is still in good shape. It may be required to replace the lead flashing to repair a leaking roof valley, as this is the most prevalent cause of problems.


Condensation is a severe concern for homeowners that can lead to a variety of issues, including roof leaks. Due to the way air rises and the fact that it is directly between interior and outside temperatures, the loft space is especially prone to condensation. Condensation occurs when heated air collides with a cold surface, therefore this can act as a catalyst. If condensation is a problem in your home, the moisture can build up and eventually leak down into your loft’s floor, causing water damage.

You might detect a leak coming from your attic, or perhaps just a strong, musty odour from damp timbers, which can lead to decay, mould, and mildew growth. Installing appropriate roof ventilation, which allows warm air and excess moisture to escape, is an efficient way to reduce condensation in your loft space. Another option is to improve your loft insulation, which will maintain a constant temperature and remove extra moisture from the air.

Condensation must be stopped as soon as possible, since it poses a major threat to the structural integrity of your roof, especially if the timbers have been damaged by water for a long time.

Soffit and fascia boards

Soffit and fascia boards keep water and vermin out of your roof space by preventing them from entering from the underside or front. However, these boards can deteriorate over time, especially if your property has a conventional wooden soffit and fascia. The timber can soften as a result of issues such as leaking gutters that can spill over onto your home’s façade, eventually leading to holes and rot. Pests such as rats and birds, as well as water penetration, are attracted to these locations. We advocate replacing the soffit and fascia boards with modern UPVC, which is almost impervious to the problems that affect old wood and is significantly less likely to leak. Call up an experienced roofer to find out more about replacing your old soffit and fascia boards.

Leaking skylights and windows

On the plus side, a leak originating from one of your roof windows is likely to be the easiest to detect and diagnose, as it should be rather evident. However, if leaks are coming from the top of your roof window or skylight, it’s possible that the flashing around it, rather not the window itself, is damaged. Aside from acute damage such as hits from falling debris or age-related wear-and-tear, incorrect installation is the most common cause of a leaky roof window.

Clear the area of any debris, especially moss or mud, before attempting to fix a leaky roof window. Then, carefully examine every portion of your window for cracks or other signs of deterioration. Seal these cracks with resin or silicone once you’re sure you’ve found everything you’re going to find. Even if you don’t think it’s the problem, now is a good opportunity to take a closer look at your window flashing, since there may be some warning signals that will create problems in the future.

Roof vents

Roof vents are an important feature of a healthy roof because they allow warm air to leave and excess moisture to escape from your loft. You’d rapidly run into issues like wet, condensation, and more if your roof didn’t have enough ventilation. Roof vents, on the other hand, can create leaks in a variety of ways, including cracks in the vents or damage to the flashing used to seal around where they protrude from your roof. If a roof vent is leaking, look for black stains beneath it, which indicate moisture ingress.

If your roof vent is leaking, the first thing a roofer will do is pry up and remove the rubber boot around the base of the vent with a tool like a knife. Then they will pry up any tiles that are in the way. They will replace the flashing, rubber vent boot, or vent itself, whichever portion was causing the problem. Then, they’ll simply replace the roof tiles in their original positions, and the job’s finished!


Your property’s gutters are integral. Maintaining a building necessitates a well-functioning guttering system. If your gutters become clogged, they will stop working correctly and may begin to leak. As collecting water enters fractures and weak points in your roof space, you’ll be more likely to have a roof leak. Clogged gutters should be easy to spot, as leaves, twigs, and other debris may protrude from the top, especially in the autumn. During heavy rain, you may also observe that not much water is going through the downspout.

Unfortunately, the only option to clean your gutters is to climb a ladder and clear the debris manually. Start by removing the larger pieces of trash with your hands or a plastic scoop, which may then be discarded onto a plastic sheet below. Once you’re sure your gutters are clear, test them by pouring water into the top and watching if it makes it to the bottom. We recommend examining your gutters at least once a year, preferably at the beginning of spring and winter.


Ice damming happens when ice forms a dam along the edges of your roof, preventing snow or rainfall from exiting. The weight of pooling water or trapped snow, as well as the damage caused by water entering your roof area through any fractures or weak places, can cause extremely serious problems. When snow on your roof melts owing to the warmth of the residence below, the water rushes towards the cooler edge of your property, freezing and forming an ice dam.

Dealing with damming ice or too much snow on your roof can be dangerous, and it’s better to wait until the snow melts before attempting to remove it.

Leaky chimney

Our chimneys take a battering over their lifetime, and after repeated exposure to harsh weather, the mortar which holds it all together can wear away, offering an entrance to water. The most common place where a chimney may be causing a roof leak is in the mud cap or the mortared portion at the top of the chimney. Aside from that, you should also inspect the mortar and flashings around the base of your chimney, to ensure they haven’t been damaged.

Repairing chimneys is difficult, and depending on the issue you’re facing, may require specialist tools. Therefore, if you’ve got a roof leak coming from your chimney, it’s best to leave repairing it to a qualified professional. Whilst this is more expensive than trying it yourself, you’ll be safe in the knowledge that the job is being done right.


With all of these root causes, we recommend calling in a roofing team to come and have a look at what could be causing the leaking. Even if the problem seems simple, or small, experienced roofers will know how to fix it well, within budget and so that it doesn’t break again! Get in contact with our expert roofers on 01288 381256.