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Mold from a Leaking Roof: The Uninvited Guest You Don’t Want in Your Home

Mold from a Leaking Roof

Why Should I Worry About Mold Caused by A Roof Leak?

If there were a hall of fame devoted to things that cause mold growth in the home, then a leaky roof would be like Babe Ruth. A leaky roof is one of the worst causes of mold growth in any home because they are able to go undetected for so long.

If you are not positive that your roof is in good condition, then there is always a chance that there is a leak, and where there is a leak there is almost assuredly mold.

Mold growth is serious business. Mold has corrosive qualities that can seriously damage your home's structural integrity.

On top of that, mold exposure can cause serious illness in your home. If you want to be positive that your home is mold free, then you need to know what causes a leaky roof and what you can do about it.



Common Causes of Roof Leaks

Age of The Roof

Old roofs have been through a lot. They've seen a lot of good weather, and they've seen a lot of bad weather.

When a roof has been through a lot, it must be properly maintained. If you have not done proper maintenance and replacement on your roof in the last fifteen years, there is a chance there are damaged or even missing shingles on your roof.

There may even be damage to the roof itself. Where there is damage, there is an opportunity for your roof to leak.

Improperly Installed Flashing

Your roof's flashing is meant to be a layer of defense against possible leaks. It is meant to add an element of waterproofing to your roof to ensure that there is no water damage. However, if the flashing on your roof was not properly installed, then there is a chance that there is an exposed area on your roof that is ripe for a leak, and eventually, a mold infestation.

Improperly Installed Skylights or Roof Windows

Once upon a time, having a skylight was considered a mark of luxury for a home. Indeed, there is something simultaneously serene and regal about being able to peer up into the sky while in the comfort of your home.

However, if your skylight, or roof window, was not properly installed, it can serve as a big welcoming sign for leaks. While a skylight leak may only leak directly into your home, it can still be a magnet for mold growth which can spread to your home's structure.

Improperly Installed or Damaged Roof Vents

Roof vents are meant for increased air circulation and good air quality for your home. However, if they have been improperly installed or damaged at any point, they could be letting moisture into your home, going right to your attic.

Missing or Broken Roof Tiles, Shingles, or Slates

On a roof, the shingles, tiles, or slates are there to protect your home from nasty weather. When any of them are damaged, missing, or entirely broken, they practically invite rainwater and mold into your attic, compromising your home's structural integrity and making it susceptible to mold.

Damaged Roofing Underlayment

Damaged tiles, shingles, or slates are one problem, but if the underlayment of your roof is damaged as well then you are in for some major problems. Unless you move to have repairs done swiftly, your underlayment is highly vulnerable to leaks and future mold growth.

Chimney Damage

When your chimney is damaged, other forms of damage are often done. For example, if there are cracks in the chimney's attachment to the roof, then that is inviting moisture and mold growth into the foundation of the roof.

Badly Placed Fixtures

When fixtures are placed into your roof, they must be placed with a game plan to prevent leaks. When they are placed in a haphazard manner, preventing leaks and mold growth becomes impossible.

Loft Space Condensation

This happens when hot, humid air moves through your insulation or gaps in your loft space. This condensation may seem like no big deal, but the truth is that it is unchecked moisture that leads to mold growth.

Storm Damage

Storms can do an incredible amount of damage to a home. A storm's damage can lead to tremendous water damage, from broken windows to blown-off shingles.

Improperly Sealed Valleys

Valleys are the places where two planes of a roof meet. When it rains, the rainwater can run down the slope of the roof. When that happens, water makes it into the weakness of the seal. From there, moisture and mold will accumulate.

Clogged Gutters

Clogged gutters may not be the first culprit you think of when you think of mold damage, but the truth is that it happens all the time. Clogged gutters can build their clog up larger and larger over time. When that happens, mold growth is inevitable due to the abundance of moisture and nutrients that the mold can eat.

The mold growth can spread on the roof until it finds an opening to enter your home.

Signs of Mold Growth from Leaking Roofs

Brown, Gray, or Green Ceiling Discoloration

One of the first signs of mold that you are likely to notice is that your ceiling may no longer look right. You may notice brown, gray, or even green discoloration. This is a tried and true sign that mold is growing on your ceiling tiles and that the integrity of your home has been compromised.

Visible Mold Growth

The most obvious sign of mold growth is being able to see the mold itself. This may seem like a no-brainer, but mold often goes unnoticed until it is too visually apparent to ignore.

An Unidentified Musty Odor

One of the tell-tale signs of mold growth is the one that is not visible. Instead, you should be aware of a pungent musty odor. Think of this smell as being similar to an old, unclean basement or attic. This odor is one of the most telling signs of mold growth in your home.

How to Deal with Mold from A Leaky Roof

Repair the Roof Leak

If you want to take care of the mold in your home, the first thing you have to take care of is the moisture source leading to mold growth. Find the leak in your roof and then make the necessary repairs. This also involves tearing out any materials damaged by mold or enabling mold growth.

Replace Moldy Building Materials

Any building materials that were affected by the mold need to be replaced, and quickly. The sad truth is that any moldy building materials that made direct contact with rainwater cannot be fully treated for mold growth.

Can Mold From A Leaking Roof Make You Sick?

Mold from a leaking roof can absolutely make you sick, particularly black mold. Mold sends out microscopic spores, which are how it spreads and latches onto different surfaces. These mold spores fly through the air until they land on a surface with the moisture and nutrients they need to survive. With those spores in the air, it is easy to accidentally inhale them. When you inhale mold spores, they can make you sick and severely impact your respiratory system.

How Long Does It Take for Mold to Grow from A Leaking Roof?

This depends entirely on how long your roof has had its leak. You can be looking at serious mold growth in a manner of days under the right (or in this case, wrong circumstances).

How Do You Prevent Mold After a Roof Leak?

If you have fixed a roof leak and have, miraculously, found no mold but are worried about mold that may develop, then the first thing you need to do is make sure that the leak is fully repaired.

When that is done, you can make up a mixture of 70% water and 30% white vinegar. Never mix chemicals; the results could be disastrous.

Spray down the area where the leak was near and apply it to it. Let it set for 15 minutes and then give the area a scrub down to loosen up any potential mold and then start to dry the area out.

If you have access to a dehumidifier, then use that.

Thoroughly drying out the scene of a leak will ensure that there is no moisture for the mold to latch onto.




If you believe your home is suffering from mold in any location, whether it's the attic, ceilings, bathrooms or anywhere else, you should get in touch with an expert on mold and its remediation.

They can help you determine what needs to be done to remedy the problem and prevent the mold from ever returning.

  • Tiffany Ellis

    Tiffany Ellis is a writer for Damage Control 911 and has been in the water damage and mold remediation industry since 2007.

  • Jim Corkern

    Jim is a water damage and structural drying technician. He's been in the water damage restoration industry for 15 years.

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