Top 10 Causes of Roof Leaks – How to Find and Fix Common Roof Leaks

They are the two most dreaded words in a homeowner’s vocabulary: a leaky roof. Water is the most insidious foe, eager to penetrate your home covering’s most vulnerable defenses. And once inside, the damage and destruction may be taking place far from the point of the initial attack, making the initial source of a roof leak difficult to identify.

a handy woman on the roof

The best homeowner defense is vigilance and fast action. Maybe a new roof is in the near future and it seems like a folly to bother with a leak.

However, even a small, out-of-the-way drip in a house that seems like nothing more than an inconvenience is a major repair bill waiting to happen!

Did you know? Roof leaks can ruin insulation, become a breeding ground for black mold, damage interior ceilings and walls, and rot the wooden framing.

So, let’s look at the ten of the most common culprits in causing your roof to leak and what you can – and should – do about them (other than recruiting a bucket brigade):

1. Villain: Age


Roofing materials, especially asphalt shingles, get old and tired. Expansion and contraction with the change in temperatures cause aging roof protection to turn brittle and eventually crack.

Years of harsh rays from direct sunlight can melt the tar that holds composition shingles together.

Father Time has not lost a battle yet and when roofing materials run up against their life expectancy, it will be time to budget for a new roof at the first sign of a leak.

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2. Villain: Brick Chimneys

leaking-chimney Source:

Have you ever seen house ruins from 200 years ago? The chimney is often the only thing standing. While brick chimneys may seem indestructible, the mortar that binds the bricks together is nothing more than a hard-working mixture of water, sand, and cement.

Exposed to the weather elements, the mortar can erode and crumble over time. Check the mud cap on top of the chimney for deterioration and inspect the mortared joints where the chimney enters the roof. If patches are required, it is a cheap and quick fix.

3. Villain: Failed Flashing

chimney-flashing Source: Runyon and Sons Roofing

Speaking of chimneys, compromised flashing is a common problem on a roof. Flashing are thin strips of metal installed at danger points for leaks around a roof. For a chimney, they are bent at a 90-degree angle to attach to both the roofing material and the brick chimney.

Flashing needs to be properly sealed to protect against water intrusion. It also needs to remain nailed in place and even if that is all squared away, the metal can rust or crack.

Expect the cost of replacing old flashing to run several hundred dollars per major penetration like chimney, depending on the job size and desired material (aluminum, lead, copper, steel, etc.).

Although it may be tempting to marshal the forces of caulking and roof cement in the battle against faulty flashing, this would be only a temporary solution best reserved for situations where you know the roof will soon be replaced.

4. Villain: Loose or Missing Shingles


If you find a shingle lying in your garden, chances are the next rainstorm will be sending water into your house. Replacing a shingle is a matter of prying off the nails from the course below and sliding the new shingle into place. Nail the newcomer down securely and then re-nail its neighbors.

Do not expect to achieve a perfect color match unless you have some leftover shingles from you existing roof that have been left out to weather as well. This procedure applies for cracked shingles as well, although you may not discover the offending shingle until a leak has already sprouted.

Depending on the pitch of the roof, this can be a DIY job or require an hour or two of a contractor’s time.

5. Villain: Vent Boot

The vent boot is a close relative of flashing. Fabricated from rubber, it slides over the plastic vent pipes that protrude from a roof to work with flashing to waterproof the junction of roof and pipe.

Vent boots can be plastic, metal, rubber, or any combination. When the gasket stops working the old boot must be pulled off, usually with the aid of a knife, and a new one installed. Like shingle work, this is a job that can be handled without a call to a contractor.

6. Villain: Holes

A hole can result in a roof from storm damage or damage by animals such as squirrels and raccoons. Roof holes can also be sneakier, living for years until an inspection uncovers them. These devious tiny holes can result from misplaced roofing nails. Or the holes in the roof could have been left over from a former antenna mounting bracket.

Again, the best fix is with a small piece of flashing under the shingle and not just a dab of caulk. This is another easy job for the homeowner or can be combined with a thorough inspection from a professional roofer.

7. Villain: Complex Roof Architecture

complex-roof-photo-render Source: 24h Plans

Your dynamic roofline may be an architect’s pride and joy and a real showstopper from the street, but all those valleys and slopes can be an invitation to disaster, if they are not properly sealed.

Installing a leak barrier that keeps water flowing off the roof and still looks attractive, is a job for professionals and expect to pay according to the complexity of your roofline.


Complex roofs can be problematic even when maintained in tip-top shape. In snowy areas a roof’s configuration may not work in helping snow slide off the top of your house. If the snow piles up, an Source: Melanson

Metal roofing, or metal ice belts (a partial metal roof usually aluminum, zinc, or copper) can also be a great option to help prevent many issues associated with the snow build-up.

8: Villain: Clogged Gutters

cleaning-clogged-gutters Source: Fabulous & Frugal

Speaking of impeded water, if your gutters are too gummed-up with junk to permit water to travel away from your roof and foundation, that is an invitation for trouble. Grab a ladder and some latex gloves and get the job done — or pay someone to clean out those clogged gutters.

The cost of professional gutter cleaning will range from $100 to $300 dollars, depending on the size of your property and the amount of debris needed to be removed.

9: Villain: Skylights

leaky-skylight-replacement Source: Kuhl’s Contracting

Who doesn’t love a skylight? They can instantly transform any room or interior space! Hopefully, yours was fitted and installed properly.

Leaks can sprout down the sides of poorly fitted skylights and rubber seal around the glass can dry out and wear out as well, ruining the water barrier.

Check for cracks in the flashing along the top and the sides of the skylight, as well as any missing or cracked shingles around it. Also, ensure the skylight was installed with proper pitch.

Most skylight leaks occur due to flashing issues or improper installation, not the failure of the glazing that comes with the skylight.

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If you discover cracks in the flashing around the skylight, or any missing or cracked shingles, then the skylight will need to be professionally repaired or replaced, with new flashing and shingles applied. If the rubber seal surrounding the skylight has dried out, then the skylight will need to be professionally replaced.

A temporary repair will involve applying high quality caulk such as Vulkem or Lexel. — The cost of a temporary repair will be anywhere from $250 to $450.

To professionally re-shingle and re-flash a leaky skylight will cost anywhere from $300 to $1,500, depending on the ease of access (number of levels/floors and steepness of the roof slope) and the amount of labor required.

Replacing a leaky skylight altogether will cost anywhere from $1,250 to $3,000 for most roofs, depending on the skylight brand and model and ease of access.

10: Villain: Shiners

Not every roofing nail finds its mark. If one has missed the rafters and protrudes into the attic it is a candidate for water damage. On cold nights in an unheated attic the exposed metal nail can frost up (hence, the “shiner”).

When the weather warms during the day the frost will melt away and begin dripping. It may not seem like much until it happens day after day after day and you suddenly have a brown spot in your bedroom ceiling. Your only short-term cost for this fix will be the purchase of side-splitting pliers and a bit of your time.

However, having moisture that causes shiners in your attic space, indicates that your attic space in not insulated nor ventilated properly. This will need to be corrected, if you want to prolong the longevity of the roof deck, as well as help minimize the chance of ice dams forming on the roof in winter.

Correcting any issues with your attic insulation and ventilation will also help improve your home’s overall comfort, energy efficiency, as well as help improve the overall performance and longevity of your roof.

attic-insulation-and-ventilation Source: Sunshine Contracting

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2 thoughts on “Top 10 Causes of Roof Leaks – How to Find and Fix Common Roof Leaks”

  1. Thank you for giving me the idea that our skylight can be the reason for the leaks we’ve been having. We don’t have any clue how we got so many leaks since the last rainstorm and the skylight will probably be the last thing that will come to mind. I’ll follow your advice and check for any cracks near the sides of the skylight and also search for any missing shingles. I can only hope that this crack filler I purchased will be enough to fix the minor damage.

  2. I had no idea that something like a complex roof could be such a problem to deal with when it comes to repairs. My father was a roofer, so he tried to teach me some ways to help prevent leaks, but he never really said anything about complicated roof patterns. His biggest concern was ventilation, which is something you brought up too.


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