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What’s Causing the Roof to Leak?

Roof leaks present multiple challenges for homeowners. They never occur at a time that is convenient, and they can lead to significant damage to the interior of your home. Their effects can linger long after the repair has been made in the form of mould growth on the interior surfaces of your home. Sometimes determining the source of the roof leak can be an even greater challenge.

The source of the roof leak on the outside of the home rarely matches where the leak appears on the inside of the home. This leads to a good deal of frustration for the homeowner who is attempting to repair it. Locating the source of a roof leak is not an exact science. It is a process of elimination due to the fact that a roof leak may have several contributing factors and may not always be the direct result of one specific problem associated with your roof.

Over time, the shingles in your roof can become loose. They may even curl or rot, and this can cause real problems for your home, not to mention that if left untreated, it can damage your entire roof. If you suspect that you have loose shingles, you should first take a look at your roof from a distance.

Can you see curling shingles or any signs of damage? If you can, you may need to get your shingles replaced. Like gutter cleaning, this is a fairly inexpensive job, but you will need to hire a roofing professional if you want to get it done properly.

How To Fix A Sagging Roof

If you have a flat roof, you may experience water collection. These pools of water can cause unnecessary strain on your roof, and over time you may find that the pressure results in leaks and drips. If you want to stop this from happening, you should find out the cause of your water collection. It may be because of wear and tear, or it may be that specific structures in your roof need replacing.

If you want to limit the damage being done by this, you should disperse the water wherever possible in order to put less strain on specific areas of the roof itself. Storms can also cause damage to your roof by causing leaks as well as structural damage.

For this reason, you should always have your roof looked at by a professional if you suspect that it has incurred damage from a storm or heavy rainfall. Top Glaze has a wide range of Melbourne roof restoration services. 

10 Most Common Causes of Roof Leaks

A roof leak is a major inconvenience that can cause a significant amount of damage to your home. Roof leaks can cause structural damage to your house, including damage to your attic, ceiling and walls.

Roof leaks can even create health and safety problems for your family. Water intrusion can cause mould and mildew to spread throughout your home. Additionally, if water finds its way to electrical wiring, a leak could become a dangerous fire hazard.

Aging Materials

This is probably the most prominent cause of roof leaks, but symptoms may present in a variety of ways, often resulting in an inability to prevent water ingress. As time passes, metal roofing materials will deteriorate due to the normal wear and tear of being constantly exposed to the elements.

Despite having a considerably long lifespan compared to other roofing materials, the continual expansion and contraction of the metal as the weather changes can impact the integrity of the roof over time. If your roof is approaching 20+ years, it might be worth having a qualified roofer inspect for any telltale signs of deterioration.

Problematic Penetrations

“Penno” is a roofer talker for ‘penetration’. In a perfect world, roof penetrations wouldn’t exist. In reality, however, they can be an unavoidable part of a building’s design. Chimneys, vent pipes, skylights, exhausts and air conditioning units are all types of penetrations – and ones that we rely on to improve the conditions of occupancy within the building.

The problem, however, is that these penetrations constitute a break in the ‘building envelope’ – the thing that keeps what’s out from getting in.

If the flashings and sealants around these weak spots are not installed or maintained correctly, there’s potential for water to enter at these points. In addition, if your roof is ten years or older, there is a chance it was installed prior to the introduction of compulsory dry panning. Dry pans are flashings explicitly designed to lead water away from penetrations – without them, the risk of water ingress is substantially increased.

Blocked Gutters Can’t Drain

Clogged Gutter

If your gutters are stuffed to the gills with leaves and other debris, they won’t be able to perform as designed. When water can’t drain efficiently, you run the risk of it overflowing into vulnerable internal spaces within the roof. Regular gutter maintenance will ensure unobstructed drainage. Looking for roof gutter cleaning services? Check out Top Glaze Melbourne.

Unfit or Poorly Designed and Installed Flashings

Flashings are sections of folded metal installed over joints in the roof construction to prevent water from seeping in and causing damage.

Sometimes it takes a bit of finesse to install these so that they’re watertight, and if the appropriate attention to detail isn’t applied, water may sneak into the roof cavity.

Box Gutters

Box gutters or ‘internal gutters’ are notoriously problematic roofing features. While often unavoidable, the nature of their design means that unless installed with 100% accuracy, water may not be able to drain efficiently.

Unlike in eaves gutters, where the majority of overflow is outside the building, water in box gutters is at a much higher risk of overflowing into the internal spaces below – spaces that are often hard to access or directly impact the function of your home.

In addition, if water is not able to drain, it may pool and lead to rusting.

Damaged or Incorrectly Installed Valley Flashings

Have you or other trades been spending too much time in the valley? Often the safest place to walk up and down a roof is along the valley, but unless your steps are exact, you may be causing damage to the turned-up edges of the valley gutters that prevent water from spilling into the roof cavity – hopefully, they were turned up in the first place!

Holes Caused by Rust and Corrosion

Well, it certainly could be! Rust is one of the most common and apparent causes of leaks. Whether it’s due to the installation of incompatible materials or the typical oxidisation process of iron, once the metal has broken down – it provides little protection from water ingress. 

What may begin as slight discolouration can develop into a serious issue over time, so it’s essential to make regular inspections and monitor the speed of deterioration. Once substantial rusting has occurred, the most efficient solution to prevent leakage is generally the replacement of the rusted elements.

However, you can rest assured that this option will put an end to your issues the first time!

Moisture and Condensation Build-up

Now, most would argue that condensation is not a leak per se. However, the long term impacts can be the same.

Water damage occurs when moisture builds upon the roof sheets’ underside and travels from the sheets to the internal spaces below.

You won’t get water pouring in, but it may lead to watermarks, stains and mould and mildew over time. Luckily, there are anti-condensation blankets that can be installed on the underside of the sheets to prevent this from happening!


Not only are they a nuisance, but the pests that get into your roof space are often also responsible for damage to your property. Their activity may be responsible for leaks in a number of ways:

  • Chewing through insulation: as mentioned above, the anti-con blanket is designed to prevent condensation build-up – if the blanket is significantly damaged, it may impede its ability to do so.
  • Chewing through plumbing: this is a bit of a red herring situation, in that it may cause you to think there is a roof leak, whereas it’s damaged plumbing. It’s becoming more commonplace that plumbing is installed in the roof these days, so this can be incredibly misleading.
  • Possum entry = water entry: You may find that a possum’s point of access is the perfect entry for water, e.g. a loose flashing, which gradually gets displaced over time as a possum squeezes in and out may allow water to enter.

Insufficient Water Runoff

The truth is, this probably isn’t something you had any control over. However, it’s also true that low pitched roofs are more susceptible to leaks. Compared to roofs with steeper pitches where downward water flow is increased, shallow or flat roofs have poorer drainage capabilities. Water, therefore, tends to pool, and leaks develop more quickly. Low sloped roofs are also more prone to uplift, and displacement may allow wind-driven rain to enter the roof cavity.

7 Unexpected Causes of Roof Leaks

So what’s the big deal with water damage? It not only ruins your property inside your home but actually attacks the physical structure of your home, causing rot and necessitating a full remodel of any part of the house it encounters. Further, mould develops and creates hazardous air quality in your home.

Damaged Roof

And the problems don’t just stop with water. Once there’s a hole, critters can get in and wreak havoc by leaving droppings and nesting in your home. This creates air quality issues and lasting problems with your home’s structure and insulation. We have a wide range of Melbourne roof replacement services at Top Glaze.


Probably one of the largest causes of roof leaks is they have simply reached the end of their life. As a roof age, it does what it was born to do — protect your home from the elements. Even perfectly maintained roofs are going to take a beating by design.

Even if nothing catastrophic happens to your roof, you can bet that once a roof reaches the end of its life — 20-25 years — you’re going to start developing some leaks.


Another big cause of roof leaks is wildlife seeking shelter when the weather turns. When animals like mice, rats, racoons, or possums get an idea in their head to break through your roof, there is not much that will stop them.

An even bigger problem with wildlife is that once there’s a small hole, they’ll find that and use it as a starting point to develop an even larger entry. The best way to ensure this doesn’t happen is to make sure debris does not build up on your roof. Critters are attracted to fallen branches and leaves, and piled up debris will eventually lead to holes in your roof.


Fallen trees and tree branches are a big reason many Hillsboro homeowners experience leaky roofs. The culprit is generally a toxic mixture of unhealthy or dead trees and stormy weather. Healthy trees can also fall and damage your roof, but it’s a lot less likely to fall with a moderate storm.

The best way to prevent this from happening is to survey the trees on your property within striking distance of your home’s roof and make sure they are healthy. If they’re not, call an arborist and see what they can do to either revive or take down the tree.

Clogged Gutters

When gutters clog, water pools. Ask any roofing expert, and they’ll tell you — standing water is bad news for your roof. While roofs are designed to be leakproof when water falls onto them and runs off, they’re not designed to hold pooled water for too long. This is not because they aren’t waterproof, but because the water’s sheer weight will force damage to the structure of your roof and cause a leak.

Gutters become clogged by debris getting jammed in the natural flow of your gutter system. This most commonly happens in autumn when the leaves are falling. During this time of year, make sure your gutters are draining as they should. You should be checking throughout the rest of the year as well — and even having them inspected, cleaned, and cleared regularly.

Not Designed Correctly for Your Roof Slope

As we mentioned above, the slope is crucial to the design of your roof. It’s what drains water efficiently and what causes your roof to operate correctly. While low-pitched roofs can still be just as leakproof as steeply pitched roofs, they do need additional underlay material to ensure proper function.

If you work with unqualified roofing contractors, even new roofs can leak if your roof is low-pitched and not properly underlaid.

Poor Venting

Improper venting with your roofs can cause leaks two different ways — through excess condensation in your attic and through leaks in the vents themselves.

If there are not enough vents, moisture building up in your attic will cause mould and mildew growth since it will have nowhere to go but to stay in the attic. This lessens your roof’s integrity and will eventually cause leaks in addition to the already existing water damage from the condensation build-up.

Conversely, if vents are not properly sealed, they’ll eventually lead to leaks around the gaskets around the vent pipes. This could be a crack, gap, or missing nail, or just one that has worn out through years of use.

Faulty Flashing

Flashing is the most important part of a roof, but most people know nothing about it. Flashings are found underneath shingles and around the joints of your roof (such as where a skylight or chimney joins a roof). This is what truly makes your roof waterproof, as it creates a watertight barrier in the pressure points your roof needs it most.

When the seal on the flashing breaks down or is installed improperly, water will seep through and cause leaking. Since these are in critical parts of your roof, it should be fixed as soon as possible when there is a flashing issue.


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