Have you ever wondered why your roof might leak when it rains hard? It doesn’t happen to everyone but many homeowners and tenants will have experienced this problem at least once. It can be frustrating, and sometimes it’s difficult to find the source of the leak. In fact, there are many reasons why you might experience a leaking roof when it rains a lot.

What causes my roof to leak when it rains hard?

There are many different reasons why your roof leaks when it rains hard. And as experienced roof plumbers, we’ve seen them all.

Overflowing valleys

A roof valley is where two roof facets meet and form an interior angle, also known as a valley. These valleys will carry plenty of water when it rains. Heavy rain and blocked valleys are not a good combination. A blockage will cause the valleys to overflow and water may pool. This water might find its way through a small gap, causing a leaking roof. The best way to avoid this is to make sure your roof valleys are in good condition and that they are not blocked up by leaves and other debris.

Roof valley in tiled roof

Leaking skylights

Skylights are often a source of leaks, especially during hard rain. Leaking around skylights might be caused by poor-quality installation, rusting metal, or even a blockage of leaves and debris around the skylight. When water pools around the skylight, it often leaks through gaps, and down into the home or building. If you have skylights, check them for rust when possible and remove any build-up of debris around the area, particularly if there is a storm on the way.

Broken roof tiles

Roof tiles don’t generally break without some kind of impact. A roof tile with a fracture or crack could be caused by a falling branch, or by someone walking on your roof, such as a repair person, roof cleaner, or antenna repair person. Sometimes, even other roofers and roof plumbers can break tiles! It goes without saying that a cracked roof tile will probably cause a roof leak when it rains hard. If you have a broken or cracked tile, make sure you repair it promptly. The same goes for a more traditional roof shingle which can actually sometimes be repaired from the inside of your roof.

Flat profile roof

A roof with a flat profile might experience a leak during heavy rain. A flat roof means it’s more likely that water will pool on your roof, and may be more likely to leak through poorly sealed gaps and into your home. Some flat profile roofs simply won’t be able to deal with a large amount of rain, so do be vigilant if you have a flat profile roof.

Broken or poor-quality ridge capping

The ridges on your roof need to be properly capped, whether they are tiled, tin, or other material. If the capping is not of good quality, or if the capping cracks or breaks, there is a good chance that you’ll experience a leak. Heavy rain makes this event much more likely. Make sure you check your capping whenever you inspect your roof. This will go a long way toward making sure broken or damaged capping isn’t the cause of your leaks.

Ridge capping with roof tiles


Chimneys aren’t as common as they once were, but they can still be the cause of roof leaks. Many homes with chimneys are quite old, and they may not have been maintained to the highest degree. Therefore, over time, the seal or concrete around the chimney might be damaged, and water could enter the roof cavity or the chimney itself. It is essential to regularly check your chimney and the surrounding area, in case this is the source of your roof leak when it rains hard.

Box gutters draining slowly

There’s a reason why they say you should clean out your gutters on a regular basis! If your box gutters are full of leaves and other debris, they won’t be able to carry water to downpipes as they should. Water will then pool in your gutters. If you experience heavy rain, the gutters will probably continually overflow, and this makes a leaking roof much more likely. Avoiding this isn’t too difficult though; simply clean out your gutters on a regular basis. If you know that there’s hard rain on the way, it can’t hurt to double-check and make sure your gutter system can handle it.

Rusty roof

Tin (corrugated iron) or steel roofs are common all over Australia. They look wonderful and they are durable. However, being metal, these kinds of roofing materials can rust over time. If your roof is metal and it’s on the older side, there is a chance that parts of the roof might be starting to rust. The same goes for a tin or steel roof that hasn’t been sealed or painted properly. When these roofs do begin to rust, holes can form. Once there are holes in the roof, it’s very easy for rain to enter, causing a leaking roof. The rain itself doesn’t even need to be heavy! Repairing a rusty roof isn’t too difficult, particularly with the help of a licensed roof plumber. Just make sure you get onto the problem quickly.

Damaged or poor-quality roof flashings

Flashings are the bits of metal that keep the edges of your roof waterproofed. They are usually made from some kind of metal, and must be installed properly. If your flashings aren’t installed to the highest quality, it’s much more likely that your roof will leak when it rains. If a flashing is loose, not flush, or not properly sealed, water can enter easily. From there, the water will likely run beneath the roof and into the ceiling, where it can start to leak through plaster and light fixtures. Incorrect installation of flashings is a common cause of leaking roof when the roof has only just been installed. Avoid this problem by hiring a well-regarded roofing company.

Downpipe spreaders leaking onto tiles

On a multi-storey home or building, water will generally flow from the upper roof, onto the eaves and lower roof area. This is done through the use of downpipe spreaders, which spreads the falling water over a larger area. These spreaders lower the amount of water falling on any one tile, and they aim to avoid leaks. However, if downpipe spreaders are blocked or not working as intended, they may be dumping a large amount of water on only one or two tiles. And if it is raining hard, this makes it much more likely that you will have a roof leak. If you notice that your downpipe spreaders are not working as intended, make sure you have them cleaned or repaired where necessary.

Rust and corrosion around fasteners

A tin or steel roof requires fasteners, which keep the sheet metal fixed to the roof frame. These fasteners should be correctly sealed and waterproofed, during the manufacturing and then installation process. However, poor or incorrect installation of roof fasteners can result in a leaky roof. Time also plays a part; the area around the seal may rust or corrode, eating away at the metal. This can create cracks and gaps, and when it rains, water will find its way into your ceiling cavity. Even if the amount of water is minimal, over time it will cause damage and create black mould patches. Weather can also create gaps around fasteners, as heat and cold will cause the metal to expand and contract throughout the year.

Did You Know? The ‘Share of total population living in a dwelling with a leaking roof, damp walls, floors or foundation, or rot in window frames of floor’ study conducted by EuroStat in 2020 identified that 25% of Males in Portugal live in such conditions. The highest out of all of the European countries that took part in the study.

So why does my roof leak only when it rains hard?

If you notice water dripping from your ceiling, it’s likely caused by one of the above problems. When this leak only occurs when there is heavy rain, it’s likely that the leak is occurring because of a heavy volume of water. This might mean there is a small gap that does let water in, but the amount isn’t noticeable unless it rains a lot. It may also be that your gutters or downpipe spreaders can cope with a normal amount of water, but flood when there is heavy rain.

What kind of damage does a leaking roof cause?

It doesn’t matter how much water is leaking through your roof. Over time, any amount of water can cause significant damage to your home. Primarily, this damage occurs to the plaster ceilings and walls. However, if the drip continues for some time, the incoming water can also damage floor finishes and even possessions. Sometimes, a fast onset means a large amount of water enters the house quickly, without the time to remove your items.

It is more common that a leak will gradually lead to black mould and damage to the plaster. However, the water from a roof leak can cause an electrical fire especially if the water finds its way through lighting fixtures. Electricity and water do not mix! If the leak is dripping water into your wall cavities, insulation, and timber frames can be compromised. If the frame of your house is built from hardwood, which isn’t sealed, the timber may begin to rot.

Finding the source of a leaking roof quickly is important so that you can minimise and stop further damage.

What should I do if my roof leaks when it rains?

When you do experience a leaking roof, you’ll need to locate the source of the leak. However, the first step should be to deal with the water that is entering your home. That might mean using a bucket to catch droplets while shifting your possessions away from the drip or the leak. This will prevent further damage, particularly if the flow of water increases.

If your roof only leaks when it rains hard, it might be tough to find the source of the leak. If this does continue to happen, you’ll need to engage the services of a roof plumber. A quality roof plumber will take the time to locate the source of the leak at your Melbourne property. Then, they will notify you of the problem, and the steps required to fix the issue.

How to repair a leaking roof?

Repairing a leaking roof is best left to the experts. It’s not a DIY job, and can be dangerous. Working at heights on a slippery roof is full of risks, so you shouldn’t try to repair your roof yourself. And chances are, you won’t be able to tackle the issue without the right tools, equipment, and materials that a plumber will have access to.

The repair process really depends on the issue itself.

For instance, if you’re experiencing a small roof leak due to a corroded fastener, it could be as simple as replacing the fastener and properly sealing the surrounding area. If you have a cracked roof tile, simply replacing that one tile should stop the leak in its tracks. These more minor repairs are affordable and will not take long to complete.

On the other hand, your leak might be caused by a more significant problem. For instance, if a crumbling chimney is the source of the problem, this may need to be rebuilt or removed entirely. In extreme cases, such as an old tiled roof with many cracked tiles, or an older metal roof with large areas of rust, the roof may need to be replaced entirely.

However, your roof plumber will explain all of this to you, so you can decide on the best course of action together.

Emergency roof plumber

Sometimes, when it rains hard, a roof leak can appear rapidly. If the volume of water is large and it is threatening your possessions, causing electrical problems, and damaging your home, you need to treat it like an emergency. It’s critical that you get this kind of leak fixed as soon as possible, to avoid potential injuries and damage to your home.

A professional emergency roof plumber like us here at North East Plumbing will come on time, and maintain clear communication with you throughout the process. We’ll explain the problem, and then commence with high-quality repairs. This will ensure that you don’t experience another roof leak when it does rain hard.